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Rock Creek Metals TMDLs


Monday, October 17, 2011

Rock Creek flows through Montgomery County, Maryland, and the northwest portion of Washington, DC, to join with the Potomac River. The watershed is 76.5 square miles with approximately 21 percent (or 15.9 square miles) in the District and 79 percent in Maryland.  Rock Creek was listed in 1998 for elevated levels of organics and metals in fish tissue and sediment in the Anacostia River. Subsequent water quality data suggested many of the pollutants of concern most likely did not contribute to the impairment, but total maximum daily loads (TMDLs) were required for lead, zinc, copper and mercury. The TMDLs were approved for Rock Creek parameters identified in the table below on February 27, 2004. 

The TMDLs were challenged in Friends of the Earth v. EPA 446 F.3d 140 (D.C. Cir. 2006) because the loads were not expressed in daily loads.  Following the case, a settlement agreement was reached between the US Environmental Protection Agency (EPA) and Anacostia Riverkeeper, Friends of the Earth, and Potomac Riverkeeper (Case No.: 1:09-cv-00098-JDB of January 15, 2009).  To meet the settlement requirements, EPA will revise the applicable TMDLs to express daily loads.  DDOE is working with EPA to collect/analyze data and revise the TMDLs for toxic parameters.  The table below lists the TMDL water bodies and pollutant pair with the current impairment status in the District’s 2014 Integrated Report.  In the table below, those water body/pollutant pairs categorized in 4a will be revised.

Toxic parameters and Impairment Status (2014 Integrated Report)

Upper Rock Creek

Arsenic Copper Lead Mercury Zinc 4,4' DDD 4,4' DDE 4,4' DDT Chlordane Dieldrin Hepatchlorn Epoxide  PAHs PCBs
  4a 4a 4a 4a                

Lower Rock Creek

Arsenic Copper Lead Mercury Zinc 4,4' DDD 4,4' DDE 4,4' DDT Chlordane Dieldrin Hepatchlorn Epoxide  PAHs PCBs
  4a 4a 4a 4a                

 

Notes

Categories reflect the District’s category definitions in the Integrated Report

Category 4a - A State developed TMDL has been approved by EPA or a TMDL has been established by EPA for any segment-pollutant combination.

Black boxes represent parameters not included in TMDL.

For more information, please see the District’s 2014 Integrated Report.

The 2004 final approved TMDL documents for metals in Rock Creek are included below.  The revised documents will be posted when available.