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carrying capacity in a stream as it produces p>ools and meanders, provides 

 cover for fish, and serve as an important medium for the production of 

 aquatic insects that are fed upon by salmonids. 



The impacts of logging, grazing, mining, irrigation, hydropower production, 

 and urbanization on fish habitat and fish production can be minimized by 

 using methods such as helicopter logging, placing roads on ridgetops, 

 outsloping road surfaces, installing and maintaining oversized culverts 

 that prevent road washouts, maintaining undisturbed streamside buffer 

 strips, trapping and treating mine tailing runoff, and maintaining flows. 

 Many of these methods are "low-tech" and relatively inexpensive. 



The sciences of hydrology, hydraulics, and fishery biology have recently 

 been applied together to produce fresh insights that flow maintenance is 

 something much more than just providing a base minimum flow in a stream. 

 In the Trinity River in northern California, the Service is conducting 

 long-term investigations and evaluations of year-round flow patterns that 

 mimic the natural hydrology. Those studies and others conclusively show 

 that a productive stream ecosystem requires high spring flows to transport 

 sediment, to clean spawning gravels, and to re-scour important side 

 channels — to create the fish rearing, spawning, and migration habitat 

 needed throughout the year. But the most instructive message gleaned from 

 such studies is that maintenance of fish production must begin with a 

 multi-disciplinary approach to manage entire watersheds. Even unrestricted 

 natural flows cannot keep up with the sediment and other water quality 

 degradation that occurs as a result of piecemeal, single disciplinary 

 oversight of land management practices. 



The U.S. Forest Service and the Bureau of Land Management have made 

 progress in their timber harvest, grazing, and mining operations under 

 multi-purpose management concepts, compared to the single-purpose scheme 

 that prevailed in the earlier part of this century. However, even when the 



