Man-Made Structures Dams restrict water flow, which reduces erosion. Entry ramps indicate recreational uses of the waterway such as boating or fishing. Effects of these activities are dependent on the pre-existing condition of the stream. Bridges and piers provide a foreign habitat that may have variable effects. Pipe outfalls indicate a point source.
Roadways increase runoff and act as a source of vehicle emissions.
L. Point Sources Point sources are not currently as much of a problem in streams as non-point sources, mostly because discharges are usually controlled with specific permit conditions. The most common point sources are industrial facilities, municipal treatment plants, and combined sewers. A point source can be identified as a flow into the stream which is not naturally occurring and which has a known origin. In order to identify the location of your point source, look downstream, in the direction in which the current is flowing. The bank on your right will be the right bank and the one on your left will be the left bank.