Problems in water treatment plants using such water range from cancer causing trihalomethanes to dark water. The longer organic mater stays in water, the more dissolved materials accumulate. Flushing by heavy rains may cause increases in turbidity while controlled releases tend to maintain a constant water color. Forestland contributes roughly .75 tons per acre per year to sediment reaching rivers and streams. Extreme care must be taken to protect water quality no mater how insignificant the overall impact is.
Fresh water produces more fresh water fish such as bass.
And of course salt water, shrimp and salt water fish. Sounds see shifts of salinity from time to time without man's influence. Water management may actually buffer these shifts. Opinions differ as to whether this is good or bad. Reduced survival can also result in an even greater reduction in productivity.