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JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION <br />Vol5, No. AMERICAN WATER RESOURCES ASSOCIATION <br />STORMWATER RUNOFF QUALITY AND QUANTITY FROM <br />TRADITIONAL AND LOW IMPACT DEVELOPMENT WATERSHEDS' <br />Erik S. Bedan and John C. Clausen <br />August 2009 <br />ABSTRACT: The quality and quantity of residential stormwater runoff from a control, traditional, and low <br />impact development (LID) watershed were compared in a paired watershed study. A traditional neighborhood <br />was built using typical subdivision standards while a LID design was constructed with best management prac- <br />tices including grass swales, cluster housing, shared driveways, rain gardens, and a narrower pervious concrete - <br />paver road. Weekly, flow - weighted, composite samples of stormwater were analyzed for nitrate + nitrite - nitrogen <br />(NO + NO -N), ammonia - nitrogen (NH -N), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total sus- <br />pended solids (TSS). Monthly composite samples were analyzed for total copper (Cu), lead (Pb), and zinc (Zn). <br />Mean weekly storm flow increased (600x) from the traditional watershed in the postconstruction period. <br />Increased exports of TKN, NO + NO -N, NH -N, TP, Cu, Zn, and TSS in runoff were associated with the <br />increased storm flow. Postconstruction storm flow in the LID watershed was reduced by 42% while peak <br />discharge did not change from preconstruction conditions. Exports were reduced from the LID watershed for <br />NH -N, TKN, Pb, and Zn, while TSS and TP exports increased. <br />(KEY TERMS: best management practices; low impact development; nonpoint source pollution; runoff; <br />stormwater management; urbanization; water quality; Connecticut.) <br />Bedan, Erik S. and John C. Clausen, 2009. Stormwater Runoff Quality and Quantity From Traditional and <br />Low Impact Development Watersheds. Journal of the American Water Resources Association (JAWRA) 45(4):998- <br />1008. DOI: 10 .1111/j.1752- 1688.2009.00342.x <br />INTRODUCTION <br />Nonpoint sources are responsible for a large por- <br />tion of the remaining water quality impairments in <br />our nation's waters (USEPA, 2002). Urban storm - <br />water runoff is one source of nonpoint pollution, and <br />is responsible for contributing excess nutrients, bacte- <br />ria, and toxic metals to receiving waters (USEPA, <br />2002). Additionally, runoff from urban construction <br />and development is reported as a source of pollution <br />for 14 of the 18 National Estuaries (USEPA, 1994a). <br />Traditional stormwater controls used in urban areas <br />were designed to collect, convey, and discharge water <br />quickly and efficiently (USEPA, 2000). Recently, the <br />concept of low impact development (LID) has been <br />introduced to mitigate the problems associated with <br />urban stormwater runoff (Prince George's County, <br />1999). LID is a design strategy to retain the storage, <br />infiltration, runoff, and ground -water recharge that <br />'Paper No. JAWRA -07- 0159 -P of the Journal of the American Water Resources Association (JAWRA). Received November 19, 2007; accepted <br />March 17, 2009. © 2009 American Water Resources Association. Discussions are open until six months from print publication. <br />2 Respectively, Natural Resource Specialist, North Central Conservation District, 24 Hyde Avenue, Vernon, Connecticut 06066; and Profes- <br />sor, Department of Natural Resources Management and Engineering, University of Connecticut, 1376 Storrs Road, Storrs, Connecticut 06269 <br />(E- Mail/Clausen: <br />JAWRA 998 JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION <br />