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Watts Branch is primarily a direct free- flowing tributary of the tidal Anacostia River, although the lower reach of the stream is tidally influenced. The Watts Branch subwatershed is generally outlined by Sheriff Road and the District line to the north, Benning Road to the south, Rollins Avenue to the east, and the tidal river to the west. Fifty-three percent of the subwatershed is in Prince George's County, with the remaining 47% in the District of Columbia. The Maryland portion is designated as MDE use I.

Dominant Land Uses: Dominant land uses in the subwatershed include residential (70%), forest cover (12%), and parkland (8%).

Physical Characteristics: The Watts Branch subwatershed is 2,404.5acres (3.8 mi2) in size and approximately 29% impervious. Elevations range from 270 feet at its subwatershed divide to 5 feet at its confluence with the tidal river. The stream, which lies completely in the Coastal Plain physiographic province, has an average gradient of 0.85% over 4.6 miles of mainstem. The lower reaches of Watts Branch, beginning in the vicinity of Kenilworth Avenue, are tidally influenced downstream to its confluence with the mainstem tidal river; this confluence occurs just below the Kenilworth Aquatic Gardens.

Biological Characteristics: In a rapid bioassessment of the District portion of Watts Branch, Johnson (1989) observed the following: 1) Species richness: Poor (5 species) -- this metric reflects the health of the aquatic community via the total number of taxa present; 2) EPT Index: Poor (0 species) -- this metric reflects the total number of pollution intolerant taxa (e.g., Ephemeroptera, Plecoptera and Tricoptera), with the number of taxa generally decreasing as water quality conditions deteriorate; 3) Biotic Index: Poor (3.84 index value, indicates organic pollution) -- this metric represents a modified "Hilsenhoff" biotic index and has utility for evaluating the presence of organic pollution; 4) EPT- Ch Ratio: Fair (0:1 ratio) -- this metric utilizes the relative abundance of indicator groups as a measure of community balance and therefore, indirectly reflects both the general degree of environmental stress and biotic conditions; 5) % Chironomidae: Poor (89%, suggesting metal and/or organic pollution, as well as, unstable physical habitat conditions) -- this metric represents the observed Chironomidae as a percent of the total observed individuals and therefore, indicates whether a stream may have metal contamination, is organically over-enriched, and/or is physically stressed; 6) % Tubificidae: Good (10 %) -- this metric reflects the observed Tubificidae as a percent of the total observed individuals, and in conjunction with the percent Chironomidae, it can be used to indicate toxicity from urban runoff, or insecticides or serious problems with organic enrichment/anoxic conditions related to sewage discharge; 7) % Dominant Species: Poor (89%, with one chironomid species) -- this metric indicates the degree of dominance by a singular species, with a skewed biotic community indicating environmental stress. Overall water quality rating: Poor. The large presence (89%) of a single, heavy metal-tolerant species (Cricotopus) indicates toxicity from urban runoff.

Condition Summary: Watts Branch is a highly urbanized subwatershed straddling the District of Columbia/Maryland border that is dominated by residential land use. The upper portions of the subwatershed are the least developed, containing relatively low density residential land use and small areas of undeveloped property. The majority of the development throughout the subwatershed occurred prior to the enactment of stormwater management requirements. The stream is heavily degraded, with major water quality concerns including high levels of fecal coliform, ortho- phosphorus, and ammonia nitrogen. Initiaitves by the District government (DCRA-ERA) and the U.S. Natural Resource Conservation Service have included the installation of grade stabilization measures to help reduce the adverse impact of uncontrolled stormflows on the mainstem. Additional initiatives by the District's Department of Recreation and MWCOG have been responsible for nearly 2,000 feet of riparian reforestation in the District portion of the subwatershed (MWCOG, 1994)