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In response to these challenges, the Clean Water Act was amended to require state environmental protection agencies to calculate pollution budgets for the impaired segments of their streams and rivers. The "impaired segments" were those reaches of a stream or river that did not meet the water quality standards for their intended uses. Models were used to calculate the "total maximum daily load" (TMDL) of pollutants entering the waterway through both point and non-point sources that would enable the stream segments to achieve their highest proposed use. The Clean Water Act's new TMDL program provides a more sophisticated framework for evaluating the impacts of non-point pollution on water quality. However, given the limitations of trying to put more and better BMPs into place, environmental protection agencies have begun to refocus some of their attention from reducing the total amount of pollutants being released within a watershed to also reducing the amount of stormwater runoff.

Environmental protection agencies have developed strategies for urban stormwater management that involve modifying a development site so that more precipitation would be retained on-site rather than flowing off of it into nearby waterways or waterbodies. These stormwater retention strategies initially stressed traditional engineering solutions, such as installing a stormwater collection system that temporarily stores the stormwater on-site in order to reduce the rate and amount of stormwater being released to a waterway. The strategies were later expanded to include various site modifications, such as constructing vegetated buffer strips or swales    (ditches), in order to encourage more stormwater to infiltrate into the ground.

Reducing the volume of urban stormwater leaving a site as runoff also offers an additional hydrologic benefit in urban watersheds – reducing flood risks ( NRC 2008 ). Besides having the potential to carry pollutants, stormwater runoff discharge increases the amount of water entering into a lake, stream or river, increasing both the water volume and flow velocity of the waterway. A relatively large amount of stormwater runoff entering a waterway over a relatively short time can quickly raise a stream's water levels beyond its banks, causing flooding that could threaten adjacent development. Stormwater contribution to a river or stream can also increase the velocity of the stream's flow, causing increased channel and bank erosion, undercutting or damaging dikes, levees and other water control structures, and scouring the stream or river bed. Stream edge or streambed erosion can impair water quality by increasing the cloudiness (or turbidity) of the waterway, which can also damage aquatic and riparian habitats.

Stormwater-induced flood risks are managed by the National Flood Insurance Act , where hydrologic models (adjusted by historical flood events) are used to forecast the potential flooding caused by a 100-year storm (a storm that has a one percent chance of occurring in any given year). The Act forces financial institutions to require homeowners within the designated 100-year floodplains to purchase flood insurance in order to get a mortgage, with the federal government subsidizing the insurance premiums if the community adopts a flood management program restricting development from extremely hazardous areas and instituting building code changes to lessen flood damage.

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Source:  OpenStax, Sustainability: a comprehensive foundation. OpenStax CNX. Nov 11, 2013 Download for free at http://legacy.cnx.org/content/col11325/1.43
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