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NBP0689 is on the North Branch Potomac River above Jennings Randolph Lake. Monthly WQ sampling is done at Kitzmiller, about 0.6 miles downstream of the bridge at MD 38. The USGS gauge located at Kitzmiller (01595000) was discontinued in 1985. The area of the North Branch Potomac watershed at Kitzmiller is 225 mi2. The land use is characterized as agriculture (20.1%), forest (73.8%), and urban (1.6%). The benthos are sampled annually with a Hester-Dendy multiplate sampler. Nutrient parameters (NO23, TKN, TP) at Station NBP0689 are low relevant to the benchmark data set and have decreased since 1986. Total nitrogen, however, is beginning to trend upward as indicated by the significant concave upward quadratic term. Sulfate concentration is high and contributes to the high conductivity at this station. Other electrolytes are contributing to increasing conductivity, possibly road salt. The high sulfate concentration is indicative of acid mine drainage and may be responsible for suppressing the pH. pH, however, is in the circumneutral range and has increased significantly since 1985. Total alkalinity has increased 5 fold at NBP 0689. The magnitude of the increase suggests that base cations may have to be added upstream to increase pH. Total organic carbon has increased at this station. For a complete examination of the Water Quality Parameters concentrations and trends see Map #1. Total abundance of stream macroinvertebrates, the number of different taxa and the proportion of sensitive taxa all increased since 1986. Benthic indices correlated most strongly with acid related parameters (pH and total alkalinity). A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 1)
Back to Land Use and Station Location NBP0534 is located on the North Branch Potomac River at Bloomington below Jennings Randolph Lake and just upstream from the confluence of the Savage River. The nearest stream gauge is USGS gauge #01598500 is located on the North Branch Potomac at Luke, MD at mile 53.3 just below the confluence with the Savage. The gauge has operated since October 1999. The drainage area above the gauge is 406mi2. The flow has been regulated by release from the Savage Reservoir since 1950 and since 1981 by Jennings Randolph Lake, 9 miles upstream. The annual benthic sample is taken with a Hester-Dendy multiplate sampler. Nutrient parameters at Station NBP0534 are all in the lower 33% of the benchmark data set. Total nitrogen is decreasing and there is no indication of a reversal in the trend in 2004. There is no trend in total phosphorus concentration. Low nutrient values are not surprising in the North Branch, Potomac River due to relatively low-density population and predominantly forested land cover. Low TSS and Turbidity values corroborate this inference. An increasing trend in TOC is possibly a result of an increase in pH which would reduce the stress on water column algal populations although this cannot be corroborated as phytoplankton chlorophyll measurements are not made at this station. Nor can increased carbon enrichment from sewage discharge be ruled out. A supporting line of evidence that this latter explanation is credible has in the quadratic term of the regression of the reduced forms of nitrogen (NH4 and TKN). The significant concave up shape of the curve indicates a possible reversal of what is now a significant decrease in concentration. For a complete examination of the Water Quality Parameters concentrations and trends see Map #2. Benthic macroinvertebrate abundance, community abundance, taxa richness and percent of sensitive taxa increased since 1985. All three indices were positively correlated with acid parameters (pH and TALK). Total abundance and total Taxa also were negatively correlated with nutrient parameters. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 2)
Back to Land Use and Station Location Monthly water chemistry samples are collected at SAV0000 from the bridge where Maryland Route 135 crosses the river just upstream of the confluence with the North Branch Potomac River. The USGS gauge #01597500 is 3.7 miles upstream from the mouth and 0.7 miles downstream from the Savage River Dam. The drainage area above the dam is 106 mi2. The gauge has operated continuously since 1948. Land use within the watershed is 86% forested, 12.7% agricultural and <1% urban. The benthos are sampled annually by Surber sampler at a location 1.1 miles above the MD 135 bridge. Concentration of nutrients, solids (dissolved and particulate), acid components and temperature were in the lower 33% of the benchmark data set. Nutrient parameters are decreasing but the trend in total nitrogen may be reversing as indicated by the significance of the quadratic term indicating a concave up scatter plot. Total organic carbon, conductivity, and pH exhibited increasing trends significant quadratic terms for pH and TOC indicate concentrations in recent years may be decreasing. For a complete examination of the Water Quality Parameters concentrations and trends see Map #3. The diversity index was the only macroinvertebrate community measure to exhibit a significant trend. The diversity index was positively correlated with pH and inversely correlated with total nitrogen. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 3) Back to Land Use and Station Location The station GEO0009 is on Georges Creek, monthly samples are taken from the right bank at Franklin, MD one mile north of Westernport. USGS gauge #01599000 has operated continuously from 1905 and is located approximately 0.3 miles upstream from GEO0009. The watershed area is 72.4 mi2. The predominant land uses (L.U > 5%) are forested (74.5%), agriculture (13.4%) and urban (6.7%). The city of Frostburg contributes 0.5 ft3/sec to Georges Creek as sewage. Frostburg obtains its water supply from the Monogahela River basin and the Savage River so the sewage discharge amounts to a 0.5 ft3/sec interbasin transfer. The benthos are sampled annually by Surber sampler. Nutrient concentrations are low at this station relative to the benchmark data set. Conductivity is high and possibly related to the high SO4 concentration. Median sulfate concentration at GEO 0009 was highest among all stations. Sulfate alone, however, cannot be the cause of high COND values as conductivity increased and SO4 did not. Alkalinity and pH both increased, suggesting that cations may have been added to manage pH shifts due to high sulfate levels. This would add to electrical conductance as well. Water temperature increased but may be heading back down in recent years. pH and TOC also had significant quadratic terms increasing a downturn in the data of more recent years. For a complete examination of the Water Quality Parameters concentrations and trends see Map #4. None of the benthic indices exhibited significant trends from 1986-2004. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 4) Back to Land Use and Station Location Station NBP 0461 is sampled from the bridge on US 220 that crosses the North Branch Potomac River between McCoole, MD and Keyser, WV. There is no gauge associated with this station. The benthos are sampled annually by Hester-Dendy multiplate sampler. Nutrient concentrations are low at this station only PO4 registers in the middle tercile of the benchmark data set. Ammonia, also, is higher at two stations that at upstream stations. Sulfate, total organic carbon and conductivity are also high. Concentrations of nutrient parameters have decreased since 1986 and there is no indication of a reversal in these trends. Both pH and TALK increased. Water temperature is in the middle tercile and a bit warmer than observed at upstream stations. DO is lower than upstream stations. DO is lower than upstream stations perhaps as a result of higher median water temperature. There is a decreased solubility of oxygen in water as temperatures increase. For a complete examination of the Water Quality Parameters concentrations and trends see Map #5. Total abundance and number of taxa (TAXA # _NBP0461) both increased since 1986. Increase in both indices are positively correlated with pH TALK, COND and negatively correlated with TN. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 5)
Back to Land Use and Station Location NBP0326 is located on the North Branch Potomac River at Pinto, MD near the western Maryland Railroad bridge. The USGS gauge at this station (#01597500) has operated since 1939. The watershed area above the Pinto gauge is 596 square miles. Land use in the watershed above (#01597500) is agriculture (12.7%), forest (86.1%) and urban (0.6%). An H-D multiplate sampler is used to take annual samples of the benthos. Nutrient concentrations at NBP0326 were in the lower tercile of the benchmark data set with the exception of PO4 which was in the middle 1/3 of all measured concentrations at all stations from 1986 to 1996. The acid parameters (pH, TALK, SO4) were also in the middle tercile suggesting that this station in the North Branch Potomac is under the influence of acid mine drainage. Dissolved oxygen was somewhat elevated at 9.6 mg/L. Conductivity was in the upper tercile and increasing. SO4 is one of the electrolytes that contribute to electrical conductance, however, sulfate decreased over the time series suggesting that other electrolytes contribute to COND and may also be increasing. Potential contributors to conductance are Cl; Ca++, Mg++. Ammonium, also, was in the upper tercile of ammonium concentrations in the benchmark data set. Among significant trends in concentration only COND, pH and TALK were increasing. All others were decreasing and no trends showed signs of reversal. For a complete examination of the Water Quality Parameters concentrations and trends see Map #6. Total abundance of benthic invertebrates and Taxa # (TAXA #_NBP0326) increased from 1986-2004. Trends in these benthic indicators were positively correlated with acid parameters (pH) and negatively correlated with total nitrogen. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 6) 
Back to Land Use and Station Location Water chemistry is sampled on Braddock Run just upstream of the confluence with Wills Creek. The station BDK0000 is near the junction of US40 and MD36. There is no operating gauge on Braddock Run. The annual benthic sample is taken using a Surber sampler. Median concentrations of all nutrient parameters are low with no significant trend except for TKN which decreased. Median conductivity was highest at the Braddock Run station of all 54 stations and increased over the time series. Sulfate was second highest at BDK0000 (highest SO4 median concentration occurred at GEO0009). Sulfate undoubtedly contributed to the high electrical conductance of the water at Braddock Run and increased alkalinity may also be playing a role. Alkalinity is frequently increased by adding base cations (Ca++ and Mg++) in order to neutralize acidity from excess sulfate both would increase electrical conductance. Total suspended solids were high in Braddock Run. Turbidity is low but increasing and the significant quadratic term indicates the trend may be reversing. For a complete examination of the Water Quality Parameters concentrations and trends see Map #7. The proportion of sensitive taxa was the only benthic index to have a significant trend. Percent EPT increased and was correlated with electrical conductance. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 7) Back to Land Use and Station Location Station WIL0013 is on Wills Creek. Monthly water chemistry samples are taken at the gauging station (01601509) located 0.15 miles below the confluence with Braddock Run and 1.3 miles upstream of the confluence with the Potomac River at Cumberland, MD. The watershed area above the station is 247mi2. Land use is 16% agriculture, 80% forested and 3% urban. The benthos are sampled by means of a Surber sampler. All nutrient parameters are low relative to the benchmark data set as would be expected in a forested watershed with little urban development. pH is low but circumneutral. Higher median TALK concentration may be a residual of upstream efforts to add alkalinity for pH control. Conductance is in the mid-tercile range and increased 34% over its initial value in 1986. Total suspended solids are, also, in the middle tercile. Total nitrogen, decreased from 1986-2004 as a result of decreases in both measured constituents (NO23 and TKN) that are used to calculate TN. For a complete examination of the Water Quality Parameters concentrations and trends see Map #8. Total taxa increased since 1986 (p<0.1) (TAXA #_WIL0013). Taxa number, however, exhibited no significant interactions with water chemistry parameters. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 8) Back to Land Use and Station Location Station NBP0103 is located on the North Branch Potomac River about 9 miles below Cumberland west of the intersection of Moores Hollow Road and MD 51, approximately 10.3 miles above the confluence with the South Branch of the Potomac. The nearest flow gauge is #01603000, which is located 9.3 miles upstream of NBP0103. The drainage area above the gauge is 875 mi2. The watershed is predominantly forested (78%). Agriculture accounts for 15% and 3.8% is urban. The benthos are sampled by a Hester-Dendy multiplate sampler. Nutrient parameters (TN, TP) are low at this station and TN concentration decreased since 1986. Total alkalinity and pH are in the middle tercile and both increased since 1986. The significant quadratic term suggests that the upward trend in pH is beginning to turn downward. Sulfate concentration, an important element of acid-base water chemistry in the North Branch, is in the middle tercile compared to the benchmark data and decreased since 1986. The quadratic term, however, indicates this downward trend may be reversing. Dissolved electrolytes have placed COND in the upper tercile and their concentration increased since 1986. Sulfate and alkalinity contributes to this increase in COND. TALK and COND were correlated. Total organic carbon is high at NBP0103. TOC is a measure of organic enrichment and can be related to algal abundance but chlorophylla measurements are not taken at stations upstream of Hancock, MD so no corroboration is possible. For a complete examination of the Water Quality Parameters concentrations and trends see Map #9. Sensitive species dropped out of the benthic macroinvertebrate community since 1986 (i.e., % EPT decreased). This decline is positively correlated with TN and inversely related to COND. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 9) Back to Land Use and Station Location Water chemistry samples are taken from the toll bridge at Old Town, MD. NBP0023 is located on the North Branch Potomac River 2.3 miles above the confluence with the South Branch Potomac River. There is not operating stream gauge at this location. The benthos are sampled by Hester-Dendy multiplate sampler. Median concentrations of nutrient parameters (TN and TP) are in the lower 33% of the benchmark data set nitrate plus nitrite, TKN and TN concentrations decreased since 1986. Total alkalinity and pH were in the middle tercile. Both increased since 1986, possibly the residual from upstream addition of lime to mitigate the effects of acid mine drainage. Median sulfate concentrations is in the middle tercile range and there is no indication of a trend. Conductivity was high at NBP0023 and increased since 1986. TALK and COND were correlated at this station. For a complete examination of the Water Quality Parameters concentrations and trends see Map #10. None of the benthic indices had significant trends and there were no significant correlations with water chemistry parameters. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 10) Back to Land Use and Station Location The station TOW0030 on Town Creek is located near the bridge on Oldtown Rd., 3 miles up stream from the confluence with the Potomac River. The USGS gauge #01609000 has operated since 2001 after a hiatus of 20 years. The watershed drainage area above the gauge is 148 mi2. The watershed is predominantly forested. The benthos are sampled by Surber sampler at Town Creek. Nutrient parameters (TN and TP) are low at TOW0030 as would be expected in a predominantly forested watershed. Total nitrogen decreased since 1986 as did TKN suggesting there has been some control over sources of reduced nitrogen within the watershed. Sulfate concentration is low so there is probably little coal mining within the watershed. Median sulfate concentration, however, has increased since 1986. Total alkalinity is low and pH is high suggesting that there has been no attempt to artificially raise the pH. Conductance is low and increased since 1986, perhaps related to increased sulfate concentration. For a complete examination of the Water Quality Parameters concentrations and trends see Map #11. None of the benthic indices exhibited significant trends at TOW0030. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 11) Back to Land Use and Station Location Station POT2766 is located on the Potomac River. Monthly water chemistry samples are taken from the MD51 bridge near Paw Paw, MD. USGS gauge #01610000 is located 250 ft. upstream of the MD 51 bridge. The area of the watershed above this gauge is 3,129 mi2. Predominant land cover is forest (74%), agriculture (23%), and urban (3%). Total nitrogen is low at POT2766 and decreased since 1986. Total phosphorus is in the middle tercile and no trend is evident. Orthophosphate, however, is also in the middle tercile and increased since 1986. Median total alkalinity concentration was high at POT2766 and no trend was apparent. pH was, also high and has increased since 1986. The quadratic term indicates a possible reversal in this upward trend. The high TALK is probably a result of upstream limestone additions to mitigate the effects of acid mine drainage. Median COND is in the middle tercile and has increased since 1986. This increase accompanies increased TALK with which COND is highly correlated at POT2766. For a complete examination of the Water Quality Parameters concentrations and trends see Map #12. Total taxa increased at POT2766 (TAXA_POT2766) and the increase was positively (but weakly) correlated with acid/base chemistry. The diversity index also increased and was negatively correlated with oxidized nitrogen components of TN (p<0.1) and positively correlated with pH (p<0.05). A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 12).
Back to Land Use and Station Location Station POT2386 is on the Potomac River at Hancock, MD. Monthly grab samples for water quality are obtained from the bridge on US 522 at Hancock, MD for station POT2386. The station is below the confluence with the North Branch Potomac and the Cacapon River. USGS stream gauge 01613000 is located 0.5 miles downstream from the bridge on US 522 and about 1.1 miles upstream of Tonoloway Creek. The drainage area is 4090 mi2 (square miles) and the period of record is from 1932 to the present. Land cover in the watershed is 75% forest, 22% agriculture and 3% urban. Low flow at this gauge is affected by release from Jennings Randolph Lake since July 1981 and Savage Reservoir since 1950. The benthos are sampled at this station by Hester-Dendy multiplate sampler. Median concentration of nutrient parameters (TN and TP) are low at POT2386 TN is decreasing and the quadratic term suggests that the trend may be reversing. The oxidized and reduced forms of nitrogen (NO23 and TKN respectively) that are combined to form total nitrogen were also low and nitrite decreased since 1986. Total alkalinity and pH were both high at POT2386. The quadratic term indicated pH may be heading downward. For a complete examination of the Water Quality Parameters concentrations and trends see Map #13. There were no significant trends among the benthic indices and no correlations between benthic indices and water chemistry parameters with significant trends. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 13) Back to Land Use and Station Location Station CON0180 is on Conococheague Creek. Water chemistry is sampled monthly from the bank at the gauging station (01614500) 0.7 miles upstream of the bridge on Fairview Rd. The watershed above the gauge is 225 mi2. The predominant land uses within the watershed are forest (74%), agriculture (20%) and urban (2%). The benthic community is sampled suing a Surber sampler. Median concentrations of nutrient parameters (TN and TP) are high at CON0180 indicating a high percentage of agricultural land in the watershed, a proximate source of domestic sewage or both. TN and TP concentrations, however, both decreased since 1986. Total alkalinity and pH are both high. Limestone geology within the Conococheague watershed is the likely cause for elevated concentrations of both of these parameters. Conductivity was high and strongly correlated with TALK. Total suspended solids and turbidity, two closely related parameters, are very high. TSS was not significantly correlated with any of the 3 land use types. For a complete examination of the Water Quality Parameters concentrations and trends see Map #14. Species diversity increased and % EPT decreased at CON0180 and only % EPT correlated weakly with significant trends. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 14) Back to Land Use and Station Location Station CON0005 is on Conococheague Creek. Monthly water samples at CON0005 are taken from the MD 68 bridge over Conococheague Creek. The bridge crosses about ½ mile upstream of the confluence of Conococheague Creek with the Potomac River at Williamsport, MD. The nearest gauge is ~ 17.5 miles upstream at Fairview, MD. The benthos are sampled annually by Surber sampler. Median concentration of total nitrogen and total phosphorus are really high at CON0005. Trends, however, indicate both constituents have decreased since 1986. Total nitrogen is the sum of oxidized nitrogen (NO2 + NO3) and reduced forms (TKN, which includes NH4). The oxidized forms dominate at CON0005 and have, also, decreased since 1986. Median concentration of total alkalinity and pH are, also, high at this station. Neither have significant trends. Conductivity is high at CON0005 and highly correlated with TALK, suggesting that Ca++ and Mg++ are dominant ions measured by COND. Total dissolved solids are high and have increased since 1986. TSS does not correlate with land use type through out the network. It is possible, however, that increased TSS is associated with urbanization within a watershed. Dissolved oxygen and chlorophyll concentration are both low and decreased since 1986. A possible explanation is that nutrient reductions brought about a decrease in phytoplankton production, which would result in lower DO through decreased photosynthesis. For a complete examination of the Water Quality Parameters concentrations and trends see Map #15. Total taxa exhibited a weak downward trend (p<0.1) and it appears as if loss of sensitive species may be related to a reduction in orthophosphate as %EPT significantly decreased (p<0.05) and correlated with decreased in PO4, TP, NO2 and TOC. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 15)
Back to Land Use and Station Location Station POT1830 is on the Potomac River. Monthly water quality samples for POT1830 are taken from the bridge on MD 34 at Shepherdstown, WV. The USGS gauge (#01618000) is located on the West Virginia side immediately downstream from the MD 34 bridge and operated from 1928-1993. The watershed area upstream of this point in the Potomac is 5936 mi2. The watershed is predominantly forested (66.8%) and agricultural (29.2%). Urban and suburban land use accounts for less than 4%. The benthic community has been monitored annually since 1974 using a Hester-Dendy multiplate sampler. Total nitrogen concentration is low and decreased over the 19 years. Total phosphorus concentration is in the middle tercile and, also, decreased. pH is low in this section of the Potomac River and there is no indication of a trend. Total alkalinity is in the middle tercile and strongly correlates with COND. Neither has a significant trend. DO is low and has a strong inverse relationship to WATEMP. Neither has a trend. For a complete examination of the Water Quality Parameters concentrations and trends see Map #16. None of the benthic indices exhibited a trend. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 16) Back to Land Use and Station Location Station ANT0366 is on Antietam Creek and monthly water chemistry samples are taken at gauging station west of MD 60 at Rocky Forge. The flow gauge 01619000 was discontinued in 1981. The benthos are sampled by Surber sampler. Total nitrogen and total phosphorus are high at ANT0366 and both decreased since 1986. TKN and PO4, components of TN and TP respectively exhibit decreased trends in concentration. The quadratic term of both, however, signify an reversal in recent years. TKN is a smaller proportion of TN (11%) while PO4 is 62.5% of TP based upon median values for these two parameters. Total alkalinity is high and pH is in the mid-range, neither exhibit significant linear trends. Conductivity is higher and is positively correlated with TALK. TSS and TURB are high at ANT0366. TURB has decreased since 1986. TURB and TSS are positively correlated, yet TURB exhibits a trend. Often TURB is a measure of CHLA and TSS. This may be the case at ANT0366 as TURB and CHLA are correlated. For a complete examination of the Water Quality Parameters concentrations and trends see Map #17. Benthic indices Total Abundance and Total Taxa decreased since 1986. Total abundance correlated with a decrease in reduced forms of nitrogen (TKN and NH4) while Total Taxa correlated with decreasing NO2. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 17)
Back to Land Use and Station Location The location of ANT0203 is on Antietam Creek at the bridge on Poffenberger Road below Funkstown, MD. The nearest USGS gauge is approximately 15 miles downstream below Burnside Bridge near Sharpsburg, MD. The drainage area at the gauge is 281 square miles. The watershed is predominantly in agriculture (58%), forest cover is 32% and 12% is urban. The benthos are sampled by Surber sampler at ANT0203. Nutrient parameters (TN and TP) are high at ANT0203 concentrations of these constituents have decreased since 1986. TN is calculated from the sum of oxidized forms of nitrogen (NO23) and reduced forms of nitrogen (TKN). The latter, decreased since 1986 but the quadratic term indicates the trend may be reversing. TKN represents about 12% of the total nitrogen in 2004. Total alkalinity is high and pH is high. pH increased, albeit a small amount, since 1986. Antietam Creek flows through limestone substrate, which contributes calcium and magnesium to surface water. Both CA++ and Mg++ contribute to TALK and COND, which is positively correlated with total alkalinity at this station. TSS and TURB are high and both highly correlated. TURB alone decreased since 1986 and there is no obvious association with any measured parameter that could explain the decline. Often CHLA can contribute to the measure of turbidity and they were correlated at ANT0203. For a complete examination of the Water Quality Parameters concentrations and trends see Map #18. None of the benthic indices had significant trends at ANT0203. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 18) Back to Land Use and Station Location Station ANT0044 is located on Antietam Creek at gauge #01619500 on the left bank 400 ft. downstream from Burnside Bridge and 4.4 miles upstream from the confluence with the Potomac River. The area of the watershed is 281 mi2. The land cover is agriculture (58%), forest (32%) and urban (12%). The benthos are sampled with a Surber sampler at ANT0044. Median nutrient concentrations are high at ANT0044. Both TN and TP decreased since 1986, as did their constituent fractions (NO23 and TKN for TN and PO4 for TP). Total alkalinity and pH are both high and TALK increased since 1985. Conductivity is high and correlates with TALK. The status of both these correlated parameters is most likely due to Ca++ and Mg++ in solutions that results from the limestone substrate within the Antietam Creek watershed. For a complete examination of the Water Quality Parameters concentrations and trends see Map #19. The Hilsenhoff Biotic Index had a weakly significant trend at ANT0044 (p<0.1). The HBI increased signifying degrade conditions through organic enrichment. This increase, however, did not correlate with any of the WQ parameters. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 19) Back to Land Use and Station Location Monthly water chemistry samples are taken from the MD 17 bridge across Catoctin Creek. The USGS gauge #01637500 is located on the right bank 300 ft. below the MD 17 bridge. The watershed above the gauge is 69.9 mi2. Land cover in the watershed is agriculture (34%), forest (60%) and urban (5%). Benthic samples are taken with a Surber sampler. Total nitrogen is low and decreased since 1986. Total phosphorus is in the mid-tercile of the benchmark data set and there is no significant trend. pH is high at CAC0148. Total alkalinity is in the mid-tercile range and increased since 1986. Conductivity is correlated with TALK and, also, increased. For a complete examination of the Water Quality Parameters concentrations and trends see Map #20. None of the benthic indices had significant trends at ANT0044. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 20) Back to Land Use and Station Location Monthly water chemistry samplers are collected from the MD 464 bridge across Catoctin Creek. CAC0031 is 3.1 miles upstream from the confluence with the Potomac and 11.7 miles downstream from gauge #01637500 near Middletown, MD. The benthos are sampled by Surber sampler. Total nitrogen is in the mid-tercile range and decreased since 1986. Both constituents (NO23 and TKN) decreased and there is no indication of a reversal in trend. Total phosphorus is high and there is no trend. pH is in the mid-tercile range and decreased slightly since 1986. Total alkalinity is in the mid-tercile range and there is no indication of trend. TALK and COND are correlated and COND has increased since 1936. For a complete examination of the Water Quality Parameters concentrations and trends see Map #21. A declining trend in total abundance of aquatic macroinvertebrates was weakly significant (p<0.1) at CAC0031. This trend was correlated with decreases in the oxidized nitrogen component of TN and inversely correlated with DO. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 21). Back to Land Use and Station Location This station is located on the Potomac River at Point of Rocks. Monthly samples are taken from the riverbank on the MD side near the base of the bridge on US 15. USGS gauge #01638500 is located on the MD side (left side) just downstream from the bridge, 0.3 miles downstream from Catoctin Creek and 6 miles upstream from the Monocacy River. The area of the watershed above the gauge at Point of Rocks is 9650 mi2. Land cover is in agriculture (34%), forest (60%) and urban accounts for 2%). Annual benthic samples are taken with a Hester-Dendy multiplate sampler. Median concentration of TN and TP were in the middle-tercile. The concentration of TN and TP decreased since 1986. Total alkalinity is high and there is no indication of a trend. pH is low at POT1595 and, although, there is no significant linear trend, the quadratic term indicates a curve downward in the data. For a complete examination of the Water Quality Parameters concentrations and trends see Map #22. Total taxa exhibited a weak but significant (p<0.05) increase at POT1595 since 1986. Total Taxa correlated with nitrite at POT1595 and moved upward as NO2 and TP concentrations decreased. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 22)
Back to Land Use and Station Location Station POT1596 is on the Potomac River at Point of Rocks. Monthly water chemistry samples are taken from the bank at the base of the US 15 bridge on the VA side. USGS gauge #01638500 is located on the MD side (left side) downstream from the bridge, 0.3 miles downstream from Catoctin Creek and 6 miles upstream from the mouth of the Monocacy River. The area of the watershed above the gauge at Point of Rocks is 9650 mi2. Land cover is in agriculture (34%), forest (60%) and urban accounts for 2%). No benthic sample is taken at POT1596. Total nitrogen is in the mid-tercile range of the benchmark data set. Median TN concentration decreased since 1986. Total phosphorus concentration is high and exhibited no significant trend. Alkalinity and pH are high at POT1596. Neither showed a trend. TALK and COND were correlated at this station suggesting that Ca++ and Mg++ may be major contributors to the electrical conductance at this station. COND, also, decreased since 1986. For a complete examination of the Water Quality Parameters concentrations and trends see Map #23. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 23) Back to Land Use and Station Location Water quality was sampled monthly from the bank near the bridge on MD 140 where it crosses the Monocacy near Bridgeport, MD. USGS gauge #01639000 is located here as well. The gauge has been operating since May 1942. The area of the watershed above this point is 173 mi2. The watershed is predominantly forested (83.6%) with some urban (12.8%) and no agriculture. Benthos have been collected annually by Surber Sampler. Median concentration of total nitrogen is in the mid-tercile range of the benchmark data set and TN decreased since 1986. TN is comprised of the oxidized forms of nitrogen (NO2 + NO3) and the reduced form (TKN). NO2 concentration is low and decreased since 1986. TKN, however, was high and decreased. Total phosphorus was high and decreased since 1986. The quadratic term, however, indicates this downward trend may be reversing. TP correlated with TSS, which suggests that land disturbance (erosion) may be responsible. Its probably not agriculture, as there is reportedly little agriculture in the upper Monocacy. Total alkalinity was high at MON0528 and increased since 1986. pH was in the mid-tercile range. Conductivity was in the mid-tercile range and increased since 1986. TALK and COND were correlated (Map #24). Biotic Index decreased. The trend, however, was weak (p<0.1) and correlated with TN. For a complete examination of the Water Quality Parameters concentrations and trends see Map #24. Total abundance of benthic macroinvertebrates decreased at MON0528 (p<0.05) and was positively correlated with the decrease in TN and TP. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 24) Back to Land Use and Station Location Monthly samples are taken from the MD 194 bridge over Big Pipe Creek, near Bruceville, MD 3.5 miles upstream from confluence with Little Pipe Creek. USGS gauge #1639500 is located on the left bank 300 ft downstream from the bridge. Drainage area above the gauge is 102 mi2. Dominant land cover is agricultural (70%), forest (29%) and urban (2%). The benthos are sampled with a Surber sampler. Median concentration of total nitrogen is high and decreased significantly since 1986. Of the TN constituent nitrogen fractions NO3 dominates 86% of TN. NO2 at 0.4% of TN actually decreased. TKN (13% of TN) also decreased since 1986. Total phosphorus was in the mid-tercile range at BPC0035 and had no significant trend. PO4, however, was 57% of TP and increased since 1986 albeit a small percentage (4.2%). Total alkalinity was high and increased. TALK and COND were correlated and COND increased since 1986. pH was high and no linear trend was apparent. The quadratic term, however, indicates a down turn in the data since 1986. For a complete examination of the Water Quality Parameters concentrations and trends see Map #25. The proportion of sensitive taxa in the benthic community decreased at BPC0035 (p<0.05). % EPT correlated positively (i.e., moved in the same direction as) TN and DO. % EPT was negatively correlated with COND. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 25) Back to Land Use and Station Location Monthly water chemistry samples at MON0269 are taken from the middle of the bridge over the Monocacy River at Biggs Ford Road. There is no USGS gauge at this station and Biggs Ford Rd. crosses the Monocacy above Frederick, MD. The benthos are sampled by Surber sampler at MON0269. Total nitrogen and total phosphorus are both high at this station. Total organic carbon is, also, high suggesting a source of organic enrichment. None of these parameters exhibited a trend. Total alkalinity and pH are high. TALK increased since 1986. Conductivity is in the mid-tercile range and also increased. TALK and COND are correlated (PCC = 0.77, p<0.001). For a complete examination of the Water Quality Parameters concentrations and trends see Map #26. An increasing trend in % EPT was weakly significant (p<0.1) but did not correlate with any of the WQ parameters. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 26) Back to Land Use and Station Location Station MON0155 is on the Monocacy River. Monthly samples are taken from the boat ramp at Pine Cliffs Park on the left bank upstream of the bridge on Reels Mill Road. USGS gauge #1643000 is located on the right bank 500 ft downstream from US 70 highway bridge 0.5 miles above Pine Cliffs Park. The area of the watershed above the gauge is 817 mi2. The distribution of land cover within the watershed is agricultural (57%), forest (36%) and urban (6%). The benthos are sampled annually by Surber sampler. Total nitrogen and total phosphorus were high. Total nitrogen has decreased since 1986 and there has been no change in TP. Median TOC is high indicating organic enrichment at MON0155. Total alkalinity and pH are high most likely as a result of limestone substrate in the upper Monocacy. Photosynthetic activity can elevate pH as well but CHLA is low at this station and not likely to contribute to elevated pH. TALK and COND are correlated (PCC=0.83, p<0.001). Both increased since 1986. For a complete examination of the Water Quality Parameters concentrations and trends see Map #27. The Diversity index significantly increased. The index was correlated with pH (p<0.05). A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 27) Back to Land Use and Station Location Monthly water chemistry samples are taken from the middle of the MD 28 bridge over the Monocacy River. The bridge is 2.0 miles upstream of the confluence with the Potomac River. There is no stream gauge at this location. The benthos are sampled by Surber sampler. Median concentration of total nitrogen and total phosphorus are high at MON0020. Both, however, have decreased since 1986. The trend for total phosphorus may be reversing as indicated by the significant quadratic term. Additionally, NH4, a reduced nitrogen component of TN may also be turning upward. Median concentration of total alkalinity and pH are high and has increased since 1986. The downward concavity of the data as indicated by the quadratic term of the pH regression with time suggests that the upward trend is reversing. TALK and COND were correlated at MON0020. For a complete examination of the Water Quality Parameters concentrations and trends see Map #28. None of the benthic indices had significant trends at MON0020. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 28) Back to Land Use and Station Location This station is located where Whites Ferry crosses the Potomac River. Monthly samples are taken at the eastern terminus (MD side) of Whites Ferry. There is no stream gauge located at this station. The annual benthic sample is taken using an H-D multiplate sampler. Median concentration at total nitrogen and total phosphorus were in the mid-tercile range at POT1471. Both have decreased since 1986. Total organic carbon was, also, in the mid-tercile range. Total alkalinity and pH were high and neither exhibited a trend. Talk and COND were correlated (PCC = 0.65, p<0.0001). For a complete examination of the Water Quality Parameters concentrations and trends see Map #29. None of the benthic indices had significant trends at POT1471. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 29) Back to Land Use and Station Location Station POT1472 is located where Whites Ferry crosses the Potomac River. Monthly samples are taken at the western terminus (VA side) of the ferry route. There is no stream gauge at this location. No benthic sample is taken at POT1472. Median concentration of the nutrient parameters total nitrogen and total phosphorus were in the low and middle tercile range respectively. Total nitrogen decreased since 1986. Total alkalinity and pH are high. Neither exhibited a trend. TALK and COND were correlated at POT1472 and COND decreased since 1986. COND decreased at only one other station in the network, POT1596 approximately 12 miles upstream at Point of Rocks on the VA side of the river. COND increased at 36 (67%) of the 54 stations in the network and exhibited no change at 16 stations. Dissolved oxygen was in the lower tercile at this station but well above the state standard of 5 ppm. Water temperature was high and undoubtedly contributes to low DO at POT1472. There is an inverse relationship between DO and water temperature. TSS concentration is high and turbidity is in the mid-tercile and decreased since 1986. TSS and TURB are correlated at POT1472. For a complete examination of the Water Quality Parameters concentrations and trends see Map #30. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 30) Back to Land Use and Station Location Monthly water chemistry samples at SEN0008 are taken from the MD 112 bridge over Seneca Creek. USGS gauge #1645000 is one mile upstream of the left bank. The watershed area above the gauge is 62.8 mi2. The benthos are sampled by Surber sampler. Median concentration of total nitrogen is high at SEN0005. Median TN concentration has decreased since 1986. Although the trend is downward, the quadratic term indicates this may be reversing. This trend and reversal is due to the oxidized forms of nitrogen, which comprises 83% of the nitrogen concentration at SEN0008. The median concentration of total phosphorus is in the mid-tercile range and decreased since 1986. A median concentration of total alkalinity is in the mid-tercile range and increased since 1986. pH is high at 7.7. Median concentration of COND was in the mid-tercile range and increased since 1986. COND and TALK were not correlated at SEN0008 indicating that other electrolytes contribute to COND that are not associated with buffering capacity of the water. The scatter plot indicates that some months TALK is influenced by base cations not registered as COND. For a complete examination of the Water Quality Parameters concentrations and trends see Map #31. Total Taxa decreased since 1986 (p<0.05) and was positively correlated (i.e., moved in the same direction) with water temperature. WATEMP, however, exhibited no significant trend. Total abundance also decreased since 1986 (p<0.1) and the correlation was with nitrite. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 31)
Back to Land Use and Station Location Station CJB0005 is located on Cabin John Branch 0.5 miles upstream from the confluence with the Potomac River. Monthly samples are taken from the bridge on McCarthy Boulevard in Glen Echo, MD. There is no stream gauge presently operating on Cabin John Branch. Annual benthic sampling is done with a Surber sampler. Median concentration of total nitrogen and total phosphorus are low at CJB0005. No trend is apparent for either. Nitrite had a significant decrease in concentration since 1986. Nitrite is unstable in aerated water such as CJB and is considered to be an indicator of a proximate source of sewage. Nitrite is a relatively small proportion of the total nitrogen at CJB (0.5%). Total alkalinity and pH are both high at CJB. Total alkalinity increased since 1986. Conductivity was also high and increased. Total alkalinity and COND were not correlated. The scatter plot of the two indicates influences to COND that are not registered as TALK, indicating a possible influence of road salt in this suburban environment. Dissolved oxygen is higher than expected given the elevated water temperatures at this station. Similarly high water temperatures at other stations resulted in lower DO concentrations owing to the inverse relationship between the two. This suggests, perhaps a high stream gradient is a major contributor to the maintenance of high DO. For a complete examination of the Water Quality Parameters concentrations and trends see Map #32. None of the benthic indices had significant trends from 1986-2004. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 32) Back to Land Use and Station Location Station POT1184 is on the left bank of the Potomac River (MD side) just upstream of Little Falls Dam. Monthly samples are taken from the bank at this location. USGS stream gauge #01646500 is located on the left bank of the Potomac River (MD side) just upstream of Little Falls Dam. The area of the watershed above the USGS gauge is 11,600 mi2. Land cover proportions are forest 57%, agriculture (38%) and urban (3%). The annual benthic sample is taken by H-D multiplate sampler-deployed on the MD side just below Little Falls Dam. Median concentration of total nitrogen and total phosphorus were in the mid-tercile range at POT1184. Total nitrogen decreased since 1986 and it appears to be based upon reduction of oxidized nitrogen compound, primarily NO3 which comprises about 67% of TN. For a complete examination of the Water Quality Parameters concentrations and trends see Map #33. Total alkalinity and pH are high at POT1184 and pH increased since 1986. TALK and COND are correlated (PCC = 0.52, p<0.0001). Then benthic community indices did not have any significant trends. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 33) Back to Land Use and Station Location Station RCM0111 is located where MD 410 crosses Rock Creek. Monthly water chemistry samples are taken from the middle of the bridge. Station RCM0111 is 11.1 miles upstream from the confluence with the Potomac. The USGS gauge #01648000 is on the left bank 3.6 miles downstream near (downstream of) Sherrill Drive Bridge in Rock Creek Park. The area of the watershed above the gauge is 62.2 mi2. The benthic community is sampled annually using a Surber sampler. Median concentration of total nitrogen was low at RCM0111 and median total phosphorus concentration was in the mid-tercile and exhibited no trend. Neither component of TN, decreased from 1986. Median concentration of total alkalinity and pH were both in the mid-tercile range. Neither exhibited a trend. TALK and COND were not correlated and COND increased since 1986 suggesting an ion contaminant contributes to COND and not to base chemistry at RCM0111. For a complete examination of the Water Quality Parameters concentrations and trends see Map #34. Total Taxa (TAXA#_RCM0111), Diversity and Percent EPT all had a significant increase since 1986. Total Taxa and % EPT were correlated with and moved in the same direction as COND suggesting that habitat for pollution intolerant macroinvertebrates improved at RCM0111 since 1986. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 34) Back to Land Use and Station Location Station ANA0082 is on the Anacostia River below the confluence of the NE and NW Branches. Monthly grab samples are obtained from the bridge on Bladensburg Road. There is no stream gauge at ANA0082 and no benthic samples are taken. Median total nitrogen concentration is low at ANA0082 and has decreased since 1986. Median total phosphorus concentration is in the mid-tercile range there is no trend. Concentrations of reduced forms of nitrogen (NH4 and TKN) decreased since 1986. Total alkalinity is in the mid-tercile and increased since 1986. pH was in the mid-tercile and exhibited no trend. TALK and COND were not correlated at ANA0082. Conductivity is high at this station due to periodic mixing with higher salinity estuarine waters. For a complete examination of the Water Quality Parameters concentrations and trends see Map #35. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 35) Back to Land Use and Station Location Station PXT0972 is on the Patuxent River near Unity, MD. Monthly samples are taken from the middle of the MD 97 bridge. USGS gauge #01591000 is located on the right bank at the downstream side of the MD 97 bridge and 0.8 miles upstream from Tridelphia reservoir. The watershed above the gauge is 34.8 mi2. The land cover proportion are agriculture (53%), forest (45%) and urban (2%). The benthos are sampled by Surber sampler. Median concentration of total nitrogen is high at PXT0972. This high value is due largely to oxidized forms of nitrogen that comprise 89% of TN. The reduced form of N, TKN, was low and decreased since 1986. Median concentrations of total phosphorus was low and decreased since 1986. The median concentration of TN was 108 times greater than the median concentration of TP. Median concentration of total alkalinity was low and increased since 1986. pH was in the mid-tercile and decreased since 1986. COND was low and increased. TALK and COND were not correlated nor were TALK and pH. For a complete examination of the Water Quality Parameters concentrations and trends see Map #36. Hilsenhoff Biotic Index significantly increased since 1986. HBI increases as organic pollutants increase. The increase in HBI was inversely correlated with decreases in TP, TKN and DO. HBI moved in the same direction as COND. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 36) Back to Land Use and Station Location Station PXT0809 is located on the Patuxent River below Rocky Gorge Dam. Monthly samples are taken from the right bank. USGS gauge #01592500 is located here as well. This station is about 81 miles upstream from the mouth of the river. The watershed area above the gauge is 132 mi2. Land cover proportions are agriculture (48%), forested (44%) and urban (6%). The benthos are sampled using a H-D multiplate sampler. Median concentration of total nitrogen and total phosphorus were low at PXT0809 . Neither exhibited trends from 1986-2004. Median concentration of total alkalinity was in the mid-tercile range and increased since 1985. Median pH was 7.3 in the mid-tercile range and there was no trend. Median conductance is low and increased since 1986. TALK and COND were correlated suggesting that electrical conductance is due to dissolved cations (calcium and magnesium). Chlorophyll was high, typical of an empoundment. TN and TP are lower than input values at the top of Tridelphia Reservoir and chlorophyll concentrations are high, consistent with increased phytoplankton productivity. Increased photosynthesis would remove CO2 from the water and increase alkalinity as well. For a complete examination of the Water Quality Parameters concentrations and trends see Map #37. None of the benthic indices exhibited significant trends at PXT0809. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 37) Back to Land Use and Station Location Map #38 Station TF1.0 (PXT0603) Station TF1.0 is located on the Patuxent River and monthly samples are taken from the upstream side at the middle of the bridge carrying US 50 across the river. USGS gauge #01594440 is on the left bank about 45 feet upstream of the bridge. The watershed area above this point is 348 mi2. Land cover proportions are agricultural (46%), forested (19%) and urban (35%). The benthos are sampled monthly using a H-D multiplate sampler. A median concentration of total nitrogen was in the mid-tercile range and decreased since 1986. The quadratic term, however, indicates that the trend downward is reversing. Trends of TKN and NO23 show similar behavior. The nadir (relative minimum) in TN, NO23 and TKN appear to occur in early 2000. Median concentration of total phosphorus is high at TF1.0 and decreased since 1986. This trend, also, appears to have reversed in late 1999 or early 2000. Total alkalinity and pH are in the mid-tercile range. pH has increased since 1986. The trend appears to be reversing. Conductivity is high at this station and no trend is evident. TALK and COND are correlated. Water temperature is high and DO is low but well above the 5 ppm standard for dissolved oxygen. For a complete examination of the Water Quality Parameters concentrations and trends see Map #38. None of the benthic indices had trends at this station. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 38) Back to Land Use and Station Location Station NPA0165 is on the North Branch of the Patapsco River. Monthly samples are taken from the middle of the MD 91 bridge near Cedarhurst, MD. USGS gauge #01586000 is on the left bank at the downstream side of a private footbridge at Cedarhurst. This station is 16.5 miles upstream of the confluence with the South Branch Patapsco River. The area of the watershed above the gauge is 56.6 mi2. Land cover proportions are agriculture (51%), forested (3%) and urban (46%). The benthos are sampled using a Surber sampler. Median concentration of total nitrogen was high at NPA0165. Median concentration of total phosphorus was low and neither exhibited a trend. Total alkalinity was in the mid-tercile and the concentration increased since 1986. pH was low relative to the benchmark data and no trend is evident. Median conductivity was in the mid-tercile range and increased. TALK and COND were not correlated, possibly because of the relatively high proportion of urban land cover in the watershed with paved surfaces that are salted in winter. Chlorine increases conductance, but does not increase alkalinity of surface waters. For a complete examination of the Water Quality Parameters concentrations and trends see Map #39. The benthic indices did not have any trends at NPA0165. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 39) Back to Land Use and Station Location Station PAT0285 is on the Patapsco River 28.5 miles upstream of the mouth. Monthly samples are obtained from the MD 99 bridge near Holofield, MD. The USGS gauge #01589000 is located on the left bank at the downstream side of the MD 95 bridge. The watershed area above the dam is 285 mi2. Land cover proportions are agricultural (49%), forested (41$) and urban (8%). The benthos are sampled annually by Surber sampler. Median concentrations of both TN and TP were in the mid-tercile range. Both, also, decreased since 1986. Constituents of TN both decreased but only the reduced forms were significantly lower than 1986. Total alkalinity was in the mid-tercile range and increased significantly since 1986. pH was high relative to the benchmark data. Conductivity was in the mid-tercile range and has increased since 1986. Conductivity increased at most stations in the network (67%). COND and TALK were correlated at PAT0285. For a complete examination of the Water Quality Parameters concentrations and trends see Map #40. A declining trend in total abundance of macroinvertebrates was weakly significant (p<0.1) at PAT0258. Total abundance corrected with phosphorus and NO2 both of which decreased at this station. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 40) Back to Land Use and Station Location Station PAT0176 is on the Patapsco River 17.6 miles above the mouth. Monthly samples are taken from the bridge on Washington Boulevard (US 1). There is no stream gauge at this location. The benthos are sampled annually by Surber sampler 1.9 miles upstream from where water chemistry is sampled. Median TN and TP concentration are in the mid-tercile range of the benchmark data set. TN and TP both decreased since 1986. The decrease in TN is the result of a significant decrease in the reduced forms of nitrogen. Total alkalinity was in the mid-tercile range and increased since 1986. TALK increased at 61% of the network stations. pH was high at PAT0176 and has not changed since 1986. Conductivity was in the mid-tercile range and increased since 1986. COND increased at 67% of network stations. TALK and COND are correlated at PAT0176. For a complete examination of the Water Quality Parameters concentrations and trends see Map #41. Total abundance of macroinvertebrates in annual samples significantly decreased (p<0.05) at PAT0176. The decline was positively correlated with reduced forms of nitrogen at this station, which also significantly decreased since 1986. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 41) Back to Land Use and Station Location Station GWN0115 is on Gwynns Falls at Villa Nova. Monthly water chemistry samples are taken from the middle of the bridge on Essex Road 11.5 miles upstream from the mouth. USGS gauge #01589300 is located on the right bank 300 ft. downstream from the bridge on Essex Road. The area of the watershed above the gauge is 32.5 mi2. Land cover is agriculture (17%), forest (27%) and urban (55%). The annual benthic samples are taken with a Surber sampler. Median concentration of total nitrogen was in the mid-tercile range and decreased since 1986. Both forms of nitrogen (NO23 and TKN) decreased as well. Median concentration of total phosphorus was low and no trend was evident. TP and TSS were correlated at GWN0115. Median concentration of total alkalinity was in the mid-tercile range. TALK increased since 1986 as did conductivity, however, they were not correlated. TALK and COND were uncorrelated at 26% of all stations. pH was high at GWN0115 and no trend was apparent. For a complete examination of the Water Quality Parameters concentrations and trends see Map #42. Total abundance of macroinvertebrates declined as conductivity increased. The biotic index, an indicator that decreases as conditions improve, significantly decreased. This decline, indicating a habit improvement, was weakly correlated (p< 0.1) with decreased DO. There is no clear explanation for this relationship. It is, possibly, related to declining enrichment. As nutrients concentrations declined, CHLA decreased, although there is no correlative evidence for this. Higher levels of CHLA early in the time series could have contributed to high DO levels as oxygen is a product of photosynthesis. This argument is tenuously applied in a free flowing environment such as GWN0115 as it requires similar upstream conditions which are un measured and unknown. For a complete examination of the Water Quality Parameters concentrations and trends see Map #42. Species diversity increased and was correlated with declines in CHLA, nitrogen species and TURB. Total abundance of macroinvertebrates and the Hilsenhoff Biotic Index both decreased since 1986 (p<0.05). The trend for total abundance was significantly associated with increased conductivity. The declining HBI signifies a possible relaxation of organic pollution the HBI trend was weakly associated (p<0.1) with a decrease in DO. DO levels at 9.5 mg/L are not stressful to biota but higher levels could in the early portion of the series be related to high phytoplankton enrichment due to an abundance of nutrients. The directions of these 3 indices suggest that the habitat has improved at GWN0155. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 42) Back to Land Use and Station Location Station JON0184 is on the Jones Falls at Sorrento. Monthly water chemistry sample are taken from the bank near the USGS gauge #1589440 located on the right bank 0.3 mi downstream from the bridge on MD 25 (Falls Road). The watershed area above the gauge is 25.4 mi2. Land cover is agriculture (23%), forest (39%) and urban (38%). The benthos are sampled using a Surber sampler. Median concentration of TN was in the middle-tercile range and decreased since 1986. The median concentration of TP was low and no trend was evident. Total alkalinity was high suggesting there may be a limestone substrate in the watershed. TALK increased since 1986. pH was high and also increased since 1986. COND was high and increased but was not correlated with TALK. Conductivity may be influenced by road salt or other electrolyte not measured as alkalinity. For a complete examination of the Water Quality Parameters concentrations and trends see Map #43. The Hilsenhoff Biotic Index (HBI) significantly increased since 1986. An increase signifies a degradation of the habitat usually associated with increasing organic enrichment. Total organic carbon, however, is low at JON0184. The HBI was weakly correlated with pH (p<0.1) and moved in the same direction. We may not infer causation from this association. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 43) Back to Land Use and Station Location Station GUN0476 is on the Gunpowder River at Gunpowder Road above Prettyboy Reservoir). Monthly water chemistry samples are taken from the bridge at Gunpowder Road. There is no stream gauge at this location. The benthos are sampled using a Surber sampler. Median concentration of TN was high and no trend was evident. TKN, the reduced nitrogen compound of TN decreased since 1986 and NO23 (the oxidized nitrogen component of TN) did not. Median concentration of TP was low and decreased since 1986. Total alkalinity was in the mid-tercile range and increased since 1986. pH was high and exhibited no trend. TALK and COND were not correlated but both increased. COND was low at GUN0476 relative to the benchmark data set. For a complete examination of the Water Quality Parameters concentrations and trends see Map #44. Total abundance and proportion of sensitive species (% EPT) both decreased. The decrease in total abundance was correlated with increasing COND, as was the decline in sensitive species. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 44) Back to Land Use and Station Location Station GUN0258 is on the Gunpowder River 25.8 mi upstream from the mouth. Monthly water chemistry samples are taken from the middle of the bridge at the end of Glencoe Rd. This station is between Prettyboy and Loch Raven Reservoirs. USGS gauge #01582500 is located on the right side of the stream downstream of the bridge on Glencoe Road. The watershed area upstream of the gauge is 160 mi2. The annual benthic sample is taken using a Surber sampler. Median concentration of total nitrogen was in the mid-tercile range and no trend was evident. TKN, the reduced nitrogen component of TN, was low and decreased since 1986. Median total phosphorus concentration was low and there was no trend. Total alkalinity was in the mid-tercile range and increased since 1986. pH was in the mid-tercile range and decreased since 1986. TALK and pH were not correlated at GUN0258. Conductivity was low and increased since 1986. TALK and COND were not correlated at GUN0258. For a complete examination of the Water Quality Parameters concentrations and trends see Map #45. None of the benthic indices had significant trends. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 45) Back to Land Use and Station Location Station GUN0125 is on the Gunpowder River below Loch Raven and 12.5 miles upstream from the mouth. Monthly samples are taken from the middle of the bridge on Cromwell Bridge Road. There is no stream gauge at this location. Annual benthic samples are obtained using a Surber sampler. Median TN concentration was in the mid-tercile range and no trend was evident. The reduced forms of nitrogen (TKN) of which TN is partially comprised decreased since 1986, as did nitrite. Median total phosphorus concentration was low. PO4, a component of TP increased since 1986. Orthophosphate (PO4) increased at only 6 stations within the network (11%). Total alkalinity was in the mid-tercile range and did not have a trend. pH was high and increased since 1986. The significant quadratic term indicates that the trend for pH is reversing. Conductivity was high and was correlated with TALK. For a complete examination of the Water Quality Parameters concentrations and trends see Map #46. None of the benthic indices exhibited significant trends at GUN0125. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 46) Back to Land Use and Station Location Map #47 Station SUS0109 (CB1.0) Station SUS0109 is on the Susquehanna River. Monthly water chemistry samples are taken from the bank below the dam near the gauging station. USGS gauge #01578310 is located at the downstream side of Conowingo Dam. The watershed area above the gauge is 27,100 mi2. Land cover is agriculture (31%), forest (62%) and urban (5%). The benthos are not sampled at this location. Median concentration of total nitrogen is low at this station and has decreased since 1986. The oxidized fraction (NO23) and reducing fraction (TKN) decreased as well. TKN, however, is showing some signs of a trend reversal based on the significant quadratic term. Median concentration of total phosphorus was in the mid-tercile range and exhibited no trend. PO4, however, a component of TP increased since 1986. Orthophosphate complexes are often added to treated waste water to control metal precipitation. Total alkalinity is in the mid-tercile range and increased since 1986. pH increased as well. Conductivity was in the mid-tercile range and no trend was evident. COND and TALK were correlated. Chlorophyll was high at SUS0109, probably due to residence time of the water within Conowingo Pond. DO was in the mid-tercile range and decreased since 1986. Do, however, at 10 ppm is twice as high as the state standard. For a complete examination of the Water Quality Parameters concentrations and trends see Map #47. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 47) Back to Land Use and Station Location Station DER0015 is located on Deer Creek. Monthly water chemistry samples are taken from the middle of the bridge on Stafford Bridge Road 1.5 mi upstream from the mouth. USGS gauge #01580520 is located on the right bank at Deer Creek pumping station 3.5 mi upstream from the mouth. The drainage area above the gauge is 168 mi2. The gauge has operated since 2000. The benthos are sampled annually using a Surber sampler. Median concentration of total nitrogen is high and no trend is evident. The oxidized nitrogen component of TN (NO23) is also high. The reduced nitrogen component of TN (TKN) is low and decreased since 1986. Median concentration of total phosphorus is in the mid-tercile range and exhibited no trend. Total phosphorus and TSS were correlated at DER0015 as they were at 83% of the network stations. Total alkalinity was in the mid-tercile range and increased since 1986. pH was in the mid-tercile range and exhibited no trends . Conductivity was low and increased since 1986. TALK and COND were not correlated. TALK and COND were not significantly correlated at 26% of all stations. The status of the nutrient parameters appears consistent with an agricultural watershed that is beginning to urbanize. Dissolved nitrate plus nitrite is relatively high with a median value of over 2 mg/L. Chlorophyll a levels are low and continue to decline. DO in Deer Creek is well above the standard of 5ppm (lowest recorded value for 2002-2004 was above 7 mg/L). More roads and driveways tend to increase conductivity and more concrete infrastructure contributes to increases in total alkalinity. Increases in total suspended solids usually accompany increased building activity but does not seem to be the case in the Deer Creek watershed. Turbidity, a parameter that is highly correlated with total suspended solids (TSS), may be declining because of the decrease in chlorophyll. For a complete examination of the Water Quality Parameters concentrations and trends see Map #48. Total abundance exhibited a weak trend (p<0.1) toward lower numbers since 1986 and the trend did not correlate with any of the water chemistry parameters. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 48) Back to Land Use and Station Location Map #49 Station CHO0626 (ET5.0) Station CHO0626, more recently named ET5.0 to be consistent with CBPs station name convention, is located on the Choptank River at Red Bridge Road near Sewell, MD. Monthly samples were taken from the bank. USGS gauge #01491000 is on the left bank at the removed bridge on Red Bridges Road. This location is 62.6 mi upstream of the river mouth. The drainage area above the gauge is 113 mi2. Land cover is agriculture (55%), forest (42%) and urban (3%). Annual benthic samples are taken with a Surber sampler. Median total nitrogen concentration is in the middle-tercile of the benchmark data set and no trend is evident. Median concentration of TP is high and increased since 1986. Orthophosphate, a component of TP, is also high and increased. Total phosphorus and TSS were not correlated at CHO0626. TP and TSS were uncorrelated at 16% of all stations. Total alkalinity was low at this station and had no significant trend. pH was low and decreased since 1986, albeit by a small percentage. TALK and pH were uncorrelated. Conductivity was low and did not have a trend, not was it correlated with TALK. For a complete examination of the Water Quality Parameters concentrations and trends see Map #49. Species diversity declined since 1986. This decline correlated with increased TP, TOC and decreased pH. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 49) Back to Land Use and Station Location Station CAS0479 is on the Casselman River. Monthly samples are taken from the middle of the US 40 bridge. USGS gauge #030780000 located on the left bank at downstream side of the US 40 bridge 47.9 miles upstream from the confluence with the Youghiogheny River. Drainage area above the gauge is 62.5 mi2. A Surber sampler is used to obtain the annual benthic sample. Median total nitrogen concentration is low and decreased since 1986. The reduced nitrogen component of TN was low at CAS0479 and decreased since 1986. Median concentration of total phosphorus was low and no trend was evident. The phosphate component of TP, however, increased since 1986. Total alkalinity was low as is typical in substrate lacking limestone. pH, however, is in the circumneutral range. No trends were evident for either TALK or pH TALK and pH were correlated. Conductivity is low and increased since 1986. COND and TALK were weakly correlated at this station. These two parameters were correlated at 74% of all stations. For a complete examination of the Water Quality Parameters concentrations and trends see Map #50. Total taxa increased at CAS0479 (TAXA #_CAS0479) and was weakly correlated with changes in the oxidized nitrogen component of total nitrogen (NO23). Oxidized nitrogen, however, exhibited no trend at this station. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 50) Back to Land Use and Station Location Station CCR001 is on Cherry Creek a tributary to Deep Creek Lake. Monthly samples are taken from the middle of the bridge at Meadow Mountain Run Road. The station is 0.1 miles upstream from where Cherry Creek enters Deep Creek Lake. There is no stream gauge at this location. The benthic sample is taken by Surber sampler. Median concentration of total nitrogen was low at CCR0001 and there was no trend. Median concentration of total phosphorus was in the mid-tercile range and there was no trend. Total alkalinity is very low. TALK concentration, however, increased since 1986 quite likely due to the introduction of lime to mediate an acid mine drainage problem. pH is low and increased since 1986. TALK and pH were weakly correlated at this station. Conductivity was low and correlated with TALK. No trend in COND was evident. Total organic carbon was high. This was probably the result of increased pH. TOC increased since 1986 but the trend appears to be reversing. For a complete examination of the Water Quality Parameters concentrations and trends see Map #51. Total Taxa and species diversity increased at CCR0001. Increase number of taxa was associated with increased TOC and pH. Taxa number was inversely correlated with NH4 and DO. Species diversity index did not correlate with any of the currently measured chemical parameters. Nitrate and nitrite are no longer measured at stations within watersheds above (upstream) of Hancock, MD. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 51)
Back to Land Use and Station Location Station YOU0925 is on the Youghiogheny River 92.5 miles upstream from the confluence with the Monongahela River. Monthly samples are taken from the middle of the MD 42 bridge at Friendsville, MD. USGS gauge #03076500 is located on the left bank 0.7 miles upstream of the MD 42 bridge. The drainage area above the gauge is 295 mi2. Median concentration of total nitrogen is low and decreased from 1986. The oxidized and the reduced nitrogen component of TN decreased as well. Median concentration of TP is low and no trend was evident. Total alkalinity (10 mg/L) was low and increased since 1986. The upward trend, however, is reversing. pH is in the mid-tercile range and increased. The trend in pH, also, shows signs of reversing. TALK and pH were correlated. Conductivity was low (101 ΅mhos/cm) and increased since 1986. TALK and COND were correlated. Total organic carbon was low and increased since 1986. The trend, however, is reversing. For a complete examination of the Water Quality Parameters concentrations and trends see Map #52. None of the benthic indices had significant trends. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 52) Back to Land Use and Station Location Station YOU1139 is on the Youghiogheny River. Monthly samples are taken from the middle of the bridge where Herrington Manor Road crosses the Youghiogheny. This location is approximately Ό mile downstream of the confluence with the Little Youghiogheny River. There is no stream gauge at this location. The benthos are sampled annually using a Surber sampler. Median concentrations of TN and TP were low at YOU1139, relative to the benchmark data set. TN, also decreased since 1986. TKN, the reduced nitrogen component of TN, also decreased. No trend was evident with TP or PO4. Total alkalinity was low as was pH. Both have increased since 1986. TALK and pH were correlated at this station. TALK and COND were highly correlated, indicating that buffering cations are the major contributor to ionic strength of the water. For a complete examination of the Water Quality Parameters concentrations and trends see Map #53. None of the benthic indices exhibited significant trends at YOU1139. There is a suggestion that a decrease in the biotic index may be related to decreased ammonia but the relationship was not significant at p<0.1. A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 53) Back to Land Use and Station Location Station LYO0004 is on the Little Youghiogheny River 0.4 miles upstream from the confluence with the Youghiogheny. Monthly samples are taken from the middle of a footbridge over the Little Youghiogheny. There is no stream gauge at this location. Annual benthic samples are taken by a Surber sampler. Median total nitrogen concentration was low relative to the benchmark data set and decreased since 1986. Oxidized (NO23) and reduced nitrogen (TKN) components of TN were in the mid-tercile range and TKN exhibited a significant decreasing trend since 1986. NH4 was high and decreased since 1986. LYO0004 is among 13% of stations in this tercile of high median concentration. Total alkalinity is low and correlated with pH, which was in the mid-tercile range. pH significantly increased since 1986, but recent data indicates a downward turn. Conductivity was low and increasing. TALK and COND were correlated. For a complete examination of the Water Quality Parameters concentrations and trends see Map #54. Total taxa exhibited a weak but positively significant trend (p<0.1). Total Taxa showed strongest correlation to pH (p<0.05) and also correlated with TALK and COND (p<0.1). A graph of the number of taxa observed each year and a summary table of the Spearman Rank Coefficients and p-values for each benthic and water quality parameter measured is presented here: (Table 54)
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