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Originally Posted by SwitchBlade
Since we’re trading interesting stories
The upper Potomac River (up stream from Washington D.C.) is mostly natural right next to the river. However, there are some farms and a few housing developments near the river, and some developments further away, that have storm drainage running untreated into the river. The Potomac River empties into the Chesapeake Bay. And, since the Chesapeake Bay is one of the most economically valuable fishing and sporting areas in the country; as well as being ecologically necessary for filtering water (marshland, clams, mussels etc.), and one of the most ecologically stressed areas, the Potomac River is regularly tested for various contaminates.
One of the contaminates tested for is fecal coliform. Several years ago, the allowable contaminate level was set at a particular level that was designed to force storm water runoff to be cleaned before running into the river. The problem was that when these levels were evaluated, it was pointed out by a biologist that the level was at level lower than what would be expected from the birds, deer, bear, etc. that lived along the banks of the river (the “background” level). The levels were revised.
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I've found similar situations around here, although we don't have bears in East Yorkshire*.
The testing technique for bathing water quality is fairly simple and crude, but shows not just sewage and industrial pollution, but can show up levels from natural sources.
Much of the sources of elevated levels were from farm runoff, storm overflow, sea birds, cows, etc. The impacts from normal sewage and industrial sources have been greatly reduced.
* - Not sure which I'd rather see- a bear or the sight that used to greet me when I was sampling one particular beach which was an unoffical nudist area (unfortunately all men). Just keep your eye on the sea and keep walking. "Keep playing that guiter please".