Tohtz concluded that the the large number of riprap and dike projects in the area could be responsible for the decline in trout numbers. That is a particularly unstable and heavily populated stretch of the river, and there are a lot of riprap projects in place to prevent flood damage to homes and businesses. The result is that the river there performs more like a downspout than a natural system. Rob Hazelwood, senior staff biologist of the U.S. Fish and Wildlife Service, has long been convinced that the stabilization projects were affecting the overall health of the river. We already knew that confining the river destroys wetlands and wildlife habitat.
Nobody knows what it does to fisheries.
There is another complication. If the river is confined upstream or across from you, that power may well be redirected at your property, forcing you to consider a riprap project of your own. In late 1998, Montana Governor Marc Racicot appointed a study group to investigate what can be done to both address the concerns of landowners and preserve the Yellowstone.