On the fisheries side of the story, tail water streams below dams are some of the most productive fisheries. Cold water discharged from the bottom of the dam supplies a continuous supply of cool water to the stream below. These dams release water at certain rates, so the stream doesn’t have great fluctuations in stream flow. This makes the stream ideal trout habitat. This nutrient rich, cold water makes a fabulous trout fishery.
In New York, the East Branch of the Delaware River along the NY and Pennsylvania line gets water from the Pepacton Reservoir. This tail water stream is world famous for its trout fishing. The Pepacton Reservoir is one of the holding areas for the NYC water supply.
Every fly fisherman has heard of the Frying Pan, the South Platte and the Arkansas in Colorado, or Lees Ferry on the Colorado River in Arizona. All of these are famous gold class tail water streams. The nutrient rich, cold water makes these streams, the “dream streams” of many fly fishers. Folks like myself, travel all over the US to fish these waters. These streams draw in thousands of fisherman into the area where they purchase meals, hotels, fishing equipment, hire guides and just plain old spend money locally. Our own Ausable River is not a tail water stream, but it does bring in hundreds of fly fishermen to the area, where they spend their money. That is good for our local economy.
There are also downsides to dams. One downside is that all dams are not bottom discharge dams. Many dams have the water released from the top of the dam, or over spillways. The problem then becomes warm water. The lake behind the dam heats up during the summer and that warm water is then discharged into the stream, affecting the trout fishery below. Much depends on the size of the impoundment and supply temperature of water to the stream above the lake. Large impoundments have a greater effect on the stream below.
Rich Redman is a retired District Conservationist for the USDA Natural Resources Conservation Service and an avid outdoorsman. His column will appear regularly. He may be reached at firstname.lastname@example.org.