Water Quality Analyses (WQA) with EPA Concurrence of MDE's Findings: Little Patuxent River

The Little Patuxent River originates just north of Route 70 near the Howard County Landfill.  The River flows southeast through the heavily suburbanized area of Columbia crossing under Route 29 just south of Lake Kittamaqundi.  The Little Patuxent River continues southeast crossing under Route 32 where the Middle Patuxent River joins the Little Patuxent River in the town of Savage.  The Little Patuxent River, now larger due to the influx of the Middle Patuxent River, continues flowing southeast crossing under Route 295 and flowing through the southwest corner of the Fort Meade Military Reservation and the northeast section of the Patuxent Research Refuge.  The Little Patuxent River joins the Patuxent River just southeast of the Patuxent Research Refuge between the towns of Bowie and Crofton just before the Routes 3 and 450.  The drainage area of the Little Patuxent River watershed is 65,947 acres. 

Little Patuxent River (basin code 02131105), located in Anne Arundel County and Howard County, Maryland, was identified on the State’s list of WQLSs as impaired by cadmium (Cd) (1996), sediments (1996), nutrients (1996), and impacts to biological communities (2002 listing).  The information used for listing Cd is suspect due in part to sampling and analysis methods available at the time, and assessment inconsistencies that led to the listing in 1996.

The report available below provides an analysis of recent monitoring data, which shows that the aquatic life criteria and designated uses associated with Cd are being met in the Little Patuxent River watershed, and that the 303(d) impairment listings associated with Cd are not supported by the analyses contained herein.  The analyses support the conclusion that a TMDL for Cd is not necessary to achieve water quality standards.  Barring the receipt of contradictory data, this report will be used to support a Cd listing change for the Little Patuxent River from Category 5 (“waterbodies impaired by one or more pollutants requiring a TMDL”) to Category 2 (“Surface waters that are meeting some standards and have insufficient information to determine attainment of other standards”), when the Maryland Department of the Environment (MDE) proposes the revision of Maryland’s 303(d) list for public review in the future.  The listings for sediments, nutrients, and impacts to biological communities will be addressed separately at a future date. 
Although the waters of the Little Patuxent River watershed do not display signs of toxic impairments due to Cd, the State reserves the right to require additional pollution controls in the Little Patuxent River watershed if evidence suggests that Cd from the basin is contributing to downstream water quality problems. 

Water Quality Analysis of Cadmium in Little Patuxent River, Anne Arundel County and Howard County, Maryland

(Concurrence July 13, 2009)

EPA's Decision Letter EPA's Decision Letter

Body of the Report 

WQA_LittlePatuxent_Cd.pdf (581KB)

Comment Response Document

CRD_Little_Patuxent_Cd.pdf (7KB)


Contact Information

Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3818.