Water Quality Analysis of Eutrophication for the Jones Falls Watershed in Baltimore City and Baltimore County, Maryland

Water Quality Analyses (WQA) with EPA Concurrence of MDE's Findings:
Jones Falls


The Jones Falls watershed is located in the Patapsco River region of the Chesapeake Bay watershed within Maryland.  The watershed covers a portion of Baltimore County and Baltimore City, Maryland.  The entire Jones Falls watershed area comprises 37,290 acres (58.3 sq. mi.).

Jones Falls is a free-flowing non-tidal stream, flowing east and south from its headwaters in Garrison, MD to its discharge into the Inner Harbor in downtown Baltimore City.  An impoundment is located at Lake Roland, just north of the Baltimore County/City boundary.  Several tributaries drain to the Jones Falls mainstem, including Moores Branch, Roland Run, Towson Run, Western Run, and Stony Run.  Due to the density of the urban landscape in downtown Baltimore City, Jones Falls flows through roughly three miles of underground duct before discharging into the Baltimore Harbor.

The Jones Falls watershed (assessment unit ID: MD-02130904) was identified on the State’s 303(d) List as impaired by nutrients, sediment, copper, lead, zinc (1996 listings), fecal bacteria (2002 listing), and impacts to biological communities (2002, 2004, and 2006 listings).  Lake Roland was listed as impaired by chlordane (1996) and polychlorinated biphenyls (PCBs) (2002).  The listings for copper, lead, and zinc have been addressed by Water Quality Analyses (WQAs) showing no impairment.  The listings for fecal bacteria and chlordane have been addressed with TMDLs completed in 2006 and 2000, respectively.  The 1996 nutrients listing was refined in the 2008 Integrated Report of Surface Water Quality in Maryland (Integrated Report) and phosphorus was identified as the specific impairing substance.  Consequently, for the purpose of this report the terms nutrients and phosphorus will be used interchangeably.  A sediment TMDL was submitted to the EPA in 2009, and the listings for impacts to biological communities and PCBs in fish tissue will be addressed separately at a future date.

A data solicitation for information pertaining to pollutants, including nutrients, in the Jones Falls watershed was conducted by Maryland Department of the Environment (MDE) in November 2007, and all readily available data from the past five years have been considered.  Currently, there are no specific numeric criteria for nutrients in Maryland’s water quality standards.  Nutrients typically do not have a direct impact on aquatic life; rather, they mediate impacts through excessive algal growth leading to low dissolved oxygen.  Therefore, the evaluation of potentially eutrophic conditions due to nutrient over-enrichment will be based on whether nutrient-related parameters (i.e., dissolved oxygen levels and chlorophyll a concentrations) are found to impair designated uses in the Jones Falls watershed (in this case, water contact recreation and protection of aquatic life).

Recently, MDE developed a biological stressor identification (BSID) methodology to identify the most probable cause(s) of the existing biological impairments in Maryland 8-digit watersheds based on the suite of available physical, chemical, and land use data.  The BSID analysis for the Jones Falls watershed indicates inorganic pollutants and flow/sediment stressors are associated with impacts to biological communities; these findings will be addressed separately.  The BSID analysis did not identify any nutrient-related stressors present and/or nutrient-related stressors showing a significant association with degraded biological conditions.  The results of the BSID study, combined with the analysis of recent water quality data presented in the report below, indicate that the Jones Falls watershed is not being impaired by nutrients.  The WQA, available below,  supports the conclusion that a TMDL for nutrients is not necessary to achieve water quality standards in the Jones Falls. 

Although the waters of the Jones Falls do not display signs of eutrophication, the State reserves the right to require future controls if evidence suggests that nutrients from the basin are contributing to downstream water quality problems.  In December 2007, EPA approved TMDLs of nitrogen and phosphorus for the Baltimore Harbor.  The Jones Falls watershed is located upstream of the Baltimore Harbor and drains into the Harbor’s tidal waters.  Although the amount of nutrients entering the Jones Falls is not causing localized impairments, it is contributing to the eutrophication of the downstream tidal waters of the Harbor.  Therefore, the TMDL for the Baltimore Harbor requires nutrient reductions in the Jones Falls necessary to meet water quality standards in the Harbor.  On the same principle, additional reductions may also be required by the forthcoming Chesapeake Bay TMDL, currently under development and due to be established by EPA by the end of 2010.

Barring the receipt of contradictory data, the report will be used to support a revision of the nutrients (i.e., phosphorus) listing for the Jones Falls watershed, from Category 5 (“waterbody is impaired, does not attain the water quality standard, and a TMDL is required”) to Category 2 (“waterbodies meeting some [in this case nutrients-related] water quality standards, but with insufficient data to assess all impairments”) when MDE proposes the revision of the Integrated Report.

 

Water Quality Analysis of Eutrophication for the Jones Falls Watershed in Baltimore City and Baltimore County, Maryland

(Concurrence March 15, 2010)

EPA's Decision Letter

EPA's Decision Letter

Main Report

WQA_Jones_Falls_eutro.pdf (573KB)

Comment Response Document

CRD_Jones_Falls_eutro.pdf (10KB)

Additional Supporting Information

Biological Stressor Identification Jones Falls Watershed Report

BSID Jones_Falls.pdf (684KB)

Biological Stressor Identification Methodology Report

BSID Methodology.pdf (459KB)

 

Contact Information

Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3572.


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