Potomac River Water and Habitat Quality Assessment Maryland Department of Natural Resources Tidewater Ecosystem Assessment Tawes Building, D-2, 580 Taylor Avenue Annapolis, MD 21401 http://dnr.maryland.gov Toll Free in Maryland: 1-877-620-8DNR, ext: 8630 Out of state call: 410-260-8630 TTY users call via the MD Relay: 711 (within MD) Out of state call: 1-800-735-2258 Martin O’Malley, Governor Anthony G. Brown, Lt. Governor The facilities and services of the Maryland Department of Natural Resources are available to all without regard to race, color, religion, sex, sexual orientation, age, national origin or physical or mental disability. This document is available in alternative format upon request from a qualified individual with disability Primary Author: Renee Karrh [email protected] Contributors: Diana Domotor, Rebecca Golden, Lee Karrh, Brooke Landry, William Romano, Brian Smith, Ben Cole, Sherm Garrison, Thomas Parham, Mark Trice, Cathy Wazniak The electronic version of the report is available at http://mddnr.chesapeakebay.net/eyesonthebay/tribsums.cfm Acknowledgements: Information on the water and habitat quality of Maryland’s rivers and bays is available due to the hard work of many dedicated staff including: staff who are in the field collecting the samples year-round, sometimes under less than desirable weather conditions laboratory staff who perform the chemical tests to determine what exactly is in those water samples data management staff who collect the resulting information, confirm the accuracy and quality of the data, and organize and maintain the databases and analytical staff who interpret the data to answer the question ‘how is the river/Bay doing?’ There are too many individuals to directly name from more than 25 years of monitoring, so we simply wish to commend all of them for their commitment to collecting high quality information and making it available and useful to the citizens of Maryland. Potomac River Water and Habitat Quality Assessment i Table of Contents Table of Figures______________________________________________________________iii Table of Tables_______________________________________________________________ iv Overall Condition_____________________________________________________________ 5 Human Population and Land Use_______________________________________________ 15 Nutrient and Sediment Loadings________________________________________________ 24 Point Source Loads_______________________________________________________________ 28 Non-Point Source Loads __________________________________________________________ 32 Water and Habitat Quality_____________________________________________________ 33 Non-tidal streams ________________________________________________________________ 33 Tidal Potomac ___________________________________________________________________ 44 Shallow water ___________________________________________________________________ 54 Health of Key Plants and Animals ______________________________________________ 61 Phytoplankton___________________________________________________________________ 61 Underwater grasses ______________________________________________________________ 65 Benthos ________________________________________________________________________ 70 Summary of Water and Habitat Quality Conditions ________________________________ 72 Appendix 1 _________________________________________________________________1-1 Land use/land cover for 2000 and 2010 and Amount of Impervious Surface________________1-1 Appendix 2 _________________________________________________________________2-1 Delivered Loads to the Potomac River _______________________________________________2-1 Appendix 3 _________________________________________________________________3-1 Station names, locations and descriptions ____________________________________________3-1 Appendix 4 _________________________________________________________________4-1 Water and Habitat Quality Data Assessment Methods _________________________________4-1 Appendix 5 _________________________________________________________________5-1 Submerged Aquatic Vegetation Habitat Requirements _________________________________5-1 Appendix 6 _________________________________________________________________6-1 Annual trends results from the non-tidal water quality stations. _________________________6-1 Appendix 7 _________________________________________________________________7-1 Current status and annual trends results from the tidal water quality stations. _____________7-1 Appendix 8 _________________________________________________________________8-1 Seasonal trends results for long-term tidal water quality data ___________________________8-1 Potomac River Water and Habitat Quality Assessment ii Appendix 9 _________________________________________________________________9-1 Shallow water monitoring water and habitat quality ___________________________________9-1 Table of Figures Figure 1. Classification of Maryland tidal tributaries using percent agriculture land use vs. percent urban land use. ......................................................................................................... 12 Figure 2. Comparison of the tidal Potomac to similar systems. .................................................. 13 Figure 3. Entire Potomac basin 2010 Census data for total population by block group.............. 16 Figure 4. Upper Potomac watershed and sub-watersheds (8-digit). ............................................ 17 Figure 5. Upper Potomac land use/land cover data for 2010....................................................... 18 Figure 6. Percent Impervious Surfaces for the entire Potomac basin by sub-watershed for 2010. ............................................................................................................................................... 19 Figure 7. Middle Potomac watershed and sub-watersheds.......................................................... 20 Figure 8. Middle Potomac land use/land cover data for 2010. .................................................... 21 Figure 9. Lower Potomac basin sub-watersheds (8-digit). .......................................................... 22 Figure 10. Lower Potomac land use/land cover data for 2010. ................................................... 23 Figure 11. Watershed areas for the Potomac River by tidal river segment. ................................. 25 Figure 12. Nitrogen, phosphorus and sediment loadings per year................................................ 26 Figure 13. Wastewater treatment plant upgrades in the Potomac River Basin............................ 28 Figure 14. Annual total nitrogen and total phosphorus loadings from Blue Plains WWTP........ 29 Figure 15. Largest wastewater treatment plants discharging to the Potomac River.................... 30 Figure 16. Relative comparison of TN and TP loadings to the Potomac River by state and facility for 2011..................................................................................................................... 31 Figure 17. Long-term non-tidal water quality monitoring stations.............................................. 34 Figure 18. Annual means for total nitrogen, total phosphorus and total suspended solids in the western Upper Potomac basin non-tidal water quality monitoring stations. ........................ 36 Figure 19. Annual nitrogen loadings to the Upper Potomac at USGS gage sites and water year means for TN at long-term non-tidal water quality monitoring stations. ............................. 37 Figure 20. Annual phosphorus loadings to the Upper Potomac at USGS gage sites and water year means for TP at long-term non-tidal water quality monitoring stations....................... 38 Figure 21. Annual sediment loadings to the Upper Potomac at USGS gage sites and water year means for TSS at long-term non-tidal water quality monitoring stations............................. 39 Figure 22. Annual means for total nitrogen, total phosphorus and total suspended solids in the eastern Upper Potomac basin non-tidal water quality monitoring stations. ......................... 40 Figure 23. Annual means for total nitrogen, total phosphorus and total suspended solids in the Monocacy River and Middle Potomac non-tidal water quality monitoring stations............ 42 Figure 24. Annual nitrogen, phosphorus and sediment loadings to the USGS River Input site at Chain Bridge, Potomac. ........................................................................................................ 43 Figure 25. Long-term tidal water quality monitoring stations..................................................... 44 Figure 26. Annual means for total nitrogen in the Potomac tidal portion, 1985-2012................ 46 Figure 27. Nitrogen limitation by season in the Potomac tidal portion....................................... 47 Figure 28. Annual total phosphorus and total suspended solids in the Potomac tidal portion, 1985-2012. ............................................................................................................................ 48 Figure 29. PO4 and TSS levels compared to SAV habitat requirements, 1999-2012.................. 49 Figure 30. Salinity zone in the Lower Potomac River lower portion, 1999-2012....................... 50 Potomac River Water and Habitat Quality Assessment iii Figure 31. CHLA levels and Secchi depth compared to SAV habitat requirements, 1999-2012.51 Figure 32. Summer bottom dissolved oxygen levels in the Middle and Lower Potomac upper portions.