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Increase <br />In Area of <br />I.ecrrleus <br />Bartsees <br />Re <br />Infiltration <br />l <br />Reduatlen <br />of Dry <br />Weather <br />Strewn Plow <br />t7' <br />Reduction <br />of Ground <br />Water <br />1 d <br />Runoff <br />Mere <br />Frequent Oeor- <br />bank <br />Flew el Dtreanis <br />Flood <br />Damage <br />L..■■••■ <br />Strome Bask <br />Ereulsa <br />Runoff <br />Pollution <br />Eroelee led <br />Ingresses <br />U S ded <br />Sellds <br />Increased <br />Leads of N. <br />P. Pb. Cu. <br />Za and SOD <br />Siltation <br />of Streams <br />end <br />Reservoirs <br />Deterioration <br />of <br />Stream Health <br />Figure 2. Interaction of stormwater problems. <br />• <br />A comprehensive strategy for stornwater man- <br />agement implies (a) <br />1) A joint approach for the following tasks <br />controlling increases in runoff peaks, (b) prevent- <br />ing losses in infiltration (c) controlling runoff pol- <br />lution, and (d) reducing thermal pollution; <br />2) linking together a "treatment trait" of mea- <br />sures with functions that complement each other <br />to implement tasks shown above, and <br />3) a clustering and combination of <br />stormwater measures to form a vegetated ri- <br />parian greenway that, together with flood - <br />plains and wetlands, form a stream valley <br />Figure 3. Typical changes in runoff flows from paved surfaces affecting <br />the water budget. <br />etas <br />EMS <br />TEAlP ATIOE <br />NATURAL <br />GROOM <br />COVED <br />SNAGGY 1E► <br />■1[T1ATan <br />21%IR OFF <br />2OS <br />n <br />T1A100AT0E <br />31 -6011 <br />PAVED <br />SURFACES <br />25 l OEP <br />$Iwo. i mO1iI11AT1011 <br />01RTWA200 10% <br />25 NOR <br />2* <br />s <br />EFRflATO <br />2113 <br />3/A <br />nTUW AT00 <br />11-20% <br />471 <br />PAVED <br />SURFACES <br />aAUD11 1 •IIEPTYTOS <br />WSW <br />75 -1111% <br />PAVED <br />saA AOSMf <br />Sees J.T. T..Wr sad R Vhge.wa. Warr Rsrear hatroefra Tarak F A Mmsd at d Mmans r hater Ilbafr <br />Rsneaw At Las/ anakM.vot p. 3. <br />16 JOURNAL OF SOIL AND WATER CONSERVATION <br />and open space system that structures ex- <br />pansion on the urban fringe and offers sec- <br />ondary benefits by (a) providing a scenic <br />setting for adjacent uses, (b) forming corri- <br />dors of natural areas for wildlife protection <br />and passive recreation, and (c) by separating <br />and screening incompatible uses. <br />Interactions of stormwater problems <br />Stormwater problems all relate to increas- <br />es in impervious surfaces and tend to inter- <br />act-Tr tgtrre 2 ' ustrates. a effect is the <br />conversion of "natural" streams into "urban" <br />streams. Higher and more extended flooding <br />leads to streambank erosion and to the <br />"slumping" of streambanks. This in turn <br />causes the toppling of riparian vegetation, <br />loss of shade, stream warming, and reduced <br />oxygen—carrying capacity. Sediments caused <br />by erosion from streambanks and from con- <br />struction sites combine with runoff pollu- <br />tants from paved surfaces: nitrogen, phos- <br />phorus, lead, zinc, copper, and oxygen <br />consuming wastes. Through siltation, <br />streams and reservoirs become shallow and <br />more responsive to warming. These phe- <br />nomena coincide with reduction of base <br />flow, particularly in headwater streams, <br />caused by the sealing of the ground with <br />impervious surfaces and the reduced infiltra- <br />tion of precipitation. All of these conditions <br />lead to a deterioration of stream health. <br />Storm sewers' effect on water quality is <br />shown by differences in streambeds at their <br />point of discharge, expressed in benthic <br />algal growth (caused by nutrients), organic <br />slime on rock (caused by carbon), discol- <br />ored or black stones upon turning (caused <br />