03/04/1996 Park Board Packet - Laserfiche WebLink

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Open s ace throu h sto C1 mana , PCT h� Helping to structure growth on the urban fringe ni le at gl Jy. TobTourb er e' jc S, t1- any current events described in functional riparian "greenway" or open w the media point to the continua- _ space system. When viewed comprehensive- tion of a past trend: like it or not, ly, stormwater management offers an oppor- most future growth will continue to occur tunity to structure the present pattern of en- a in the suburbs. At subdivision and land vironmentally destructive sprawling development review meetings, one of the subdivisions known as "the suburban most frequently discussed topics is model," and provides as a bonus the protec- stormwater management. Unimaginative tion of vegetation and wildlife. d engineering approaches to stormwater The responsibility for accommodating p management, though, often leave subdivi- land use and related stormwater manage- o sions pockmarked with dry depressions in ment measures lies with municipalities who a remote corners collecting debris, while re- execute a review and approval process that tl maining "on standby" to control runoff is guided by subdivision and land develop- s from rare storm events. The costs are ment ordinances. Housing is expected to be borne by future home buyers, but the ob- the first component of the economy to re- jectives of protecting water resources and spond to the long awaited upturn from the F reducing flooding downstream are not current recession. Municipalities now have E fully realized. an opportunity to formulate an approach en- This article advocates a holistic approach abling stormwater management to function that views stormwater as a vital part of the as a tool to help structure growth that is cer- hydrologic cycle involving management tain to occur. practices to insure infiltration, control runoff pollution, reduce thermal impacts and con- The stormwater concern trol peak flows. Management practices for this kind of control put the landscape to Stormwater management had its origin in work by utilizing processes of nature such what was known in legal language as the as vegetative filtering during conveyance, "common enemy rule": draining runoff away cooling through shade trees, detention from houses and backyards as fast as possi- through depression storage, and infiltration. ble. As populations grew, this practice When implemented in settings that prior to proved to be detrimental because one per- the introduction of impervious surfaces did son's backyard drained into someone else's not experience much runoff, such manage- front yard. The runoff then accumulated, re- ment practices can be designed to form sys- sulting in flood damage downstream. For tems that function as an extension of the ex- many years the federal government was isting riparian landscape. The public is heavily involved in flood control, only to beginning to accept that bodies of water, discover an ever-increasing spiral of expen- wetlands, and floodplains are best used as ditures, but still mounting flood losses. permanent open space, protected through Today, the pollution associated with runoff land use controls. These open spaces follow is an additional concern. The first flush of stream valleys and can be expanded and en- urban runoff from cities such as Washington, hanced through stormwater management D.C., was found to be as polluted as raw practices on adjacent development sites (Fig- sewage, due to paved surfaces collecting ure 1). phosphorous-rich dust, nitrogen from acid /01 Such management practices are also open rain, and automobile related trace metals. space features and are designed in accor- Urban and suburban runoff today is the sin- dance with performance standards. gle biggest source of water pollution, limit- Stormwater management measures and ri- ing the full use of one third of the nation's parian lands can be integrated to form a waters (6). In October 1992 the U.S. Envi- 14 JOURNAL OF SOIL AND WATER CONSERVATION