美國國家研究委員會（National Research Council）最近出版一份最新報告指出，逐增的雨水水量與污染物質含量，已造成美國各城市溪流系統的水質與其棲地的破壞。
來自委員會的專家學者在報告中指出：「美國環保署的雨水因應計畫須採取根本的改變，以恢復淡水水質，並確保朝向《淨水法》（Clean Water Act）所規範的目標：可供魚釣與游泳之水質。
報告中表示：「目前美國環保署對這個問題的處理方式欠缺確的圖像，也沒有著力在控管雨水所造成的水質污染上。」領導14位委員專家撰寫此報告的是馬里蘭大學土木與環境工程教授暨都市環境研究與教育中心(Center for Urban Environmental Research and Education)執行長威爾蒂(Claire Welty)。
美國環保署表示，願意採納此報告對雨水計畫所提供的評估。此報告也是由環保署贊助美國國家委員會所撰寫。
早在1987年，美國國會已將雨水的控管列入《淨水法》中，並交由環保署監控，而現在環保署監管對象也納入城市、工業以及建築工地的雨水排放。
目前的問題是，雨水與廢水的許可標準不一樣，前者針對市區、工業和建築工地各有不同許可。
委員會於報告中指出，雨水目前的標準是沿用過去處理汙水與工業廢棄物的體制，不僅缺乏責任歸屬制度，其改善水質的效能也不穩定。
在都市區，一旦降雨和下雪後，留下來的雨水就會到處漫淹過籠罩著濕氣的街道、停車場和屋頂，帶走垃圾、柏油密合劑、汽油與其他化學物質。
最後，這些受汙染的雨水匯流至天然水道和人工排水系統，再流竄到附近的溪流、河和湖中，也流到墨西哥灣、大西洋與太平洋中。
因此，委員會在報告中向環保署建議，管理系統應該以流域為基準做統一律訂，針對該流域內所有的雨水逕流和廢水排放一體控管，而非不同的水道用不同的標準。
委員會也建議，責任歸屬制度和實行流域基準標準的權力，必須集中於某一個首要都市區，並要能與其他市區良好合作。首要都市區將獲得更多資金，承擔責任也會隨之加重。
若環保署決議不採用流域基準汙水許可標準，則可以在雨水治理計畫上作調整，例如採行委員會所建議的「綜合管理」作法，即把建築地和工業區都交由所屬的市區來管轄控制。
然而目前聯邦政府與州政府中管控許可標準的當局，並沒有也沒預期到要挪出足夠的人事職員，來對超過10萬處雨水排放來源地點進行調查並依法執行相關條例。
因此委員會認為較可行的做法，是先以市區排水系統作為初級控管。他們補充，若環保署的工業廢水源處理計畫成功，這將可以提供綜合管理策略來取鏡。
Increased water volume and pollutants from stormwater have degraded water quality and habitats in virtually every urban stream system in the United States, says a new report from the National Research Council.
The committee of experts that wrote the report says, "Radical changes to the U.S. Environmental Protection Agency's stormwater program are necessary to reverse degradation of fresh water resources and ensure progress toward the Clean Water Act's goal of 'fishable and swimmable' waters."
"EPA's current approach is not likely to produce an accurate picture of the extent of the problem, nor is it likely to control stormwater's contribution to impairing water quality," wrote the 14 member committee, chaired by Claire Welty, professor of civil and environmental engineering, and director of the Center for Urban Environmental Research and Education at the University of Maryland.
The EPA itself requested this assessment of its stormwater permitting program. and the committee's report was sponsored by the agency.
In 1987, Congress brought stormwater control into the Clean Water Act and placed it under EPA supervision. The agency now oversees stormwater discharged by cities, industries, and construction sites.
Currently, stormwater and wastewater regulations require separate permits; within stormwater regulations, different types of permits exist for municipalities, industries, and construction sites.
The current regulatory framework for stormwater, which was originally designed to address sewage and industrial wastes, has suffered from poor accountability and uncertainty about its effectiveness at improving water quality, said the committee in its report.
Following rain or snow in urban areas, large quantities of water flow over impervious surfaces, such as streets, parking lots, and rooftops, picking up garbage, asphalt sealants, motor fuels, and other chemicals.
This polluted stormwater is then collected by natural channels and artificial drainage systems and routed to nearby streams, rivers, lakes, the Gulf of Mexico and the Atlantic and Pacific oceans.
The committee recommended that the EPA adopt a permitting system based on watersheds that would encompass all discharges - stormwater and wastewater - which could impact waterways in a particular drainage basin, rather than having many individual permits.
Responsibility and authority for implementing watershed permits should be centralized with a lead municipality that would work in partnership with other municipalities, the committee suggested. The lead municipalities would receive enhanced funding to compensate for increased responsibility.
Even if the EPA decides not to adopt watershed-based permitting, adjustments could be made to the stormwater program, such as bringing construction and industrial sites under the jurisdiction of their associated municipalities, referred to as "integration" by the committee.
Federal and state permitting authorities do not have and could not expect to have enough personnel to inspect and enforce stormwater regulations on more than 100,000 point source facilities discharging stormwater.
A better structure would allow operators of municipal storm sewer systems to act as the first tier of control, the committee suggested, adding that the EPA's successful treatment program for municipal and industrial wastewater sources could serve as a model for integration.
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