Quote:
Originally Posted by Innersoul1
Correct me if I am wrong but isn't this subject to location. For examaple many of the newer communities have storm water retention ponds. This would allow for the settling of solids, however, communities that abut the river would see their storm water go directly into the water.
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More like subject to the time built. New communities require storm water ponds and facilities as a matter of subdivision requirements. These didn't exist when most of Calgary was built and are in fact quite a recent development. Storm water ponds are needed because infiltration significantly decreases with developed land (more impervious surfaces) and so more water enters the river directly without being infiltrated into the ground water table. Stormwater ponds act as holding tanks to allow water to slowly infiltrate the ground water table over time.
The whole issue with stormwater management is that water in urbanized areas entering the river is: too hot, too much, has too much dissolved minerals and has too little dissolved oxygen (or too much, I kinda forgot). Basically water flowing over impervious surfaces messes fish up.
Stormwater ponds mitigate this by reducing the volume of water flowing into the river, cooling it down, allows minerals to settle (and some to be absorbed through bio-filtration) and re-establishing an appropriate level of dissolved oxygen.
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