An extensive literature review was conducted to determine the discharge requirements of various components of a warm water fishery. Where exact hydrologic parameters were not measured directly in individual studies, they were estimated from inferred statements and knowledge of hydrologic variables leading to certain instream conditions. From this information it was possible to determine which components of the stream community would be most seriously affected by reduced discharges.
In addition, a number of different methods used in the recommendation of minimum streamflows was reviewed. These methods were evaluated for their reliability and ease of use. It was concluded that a method for recommending minimum discharges should not sacrifice reliability for expediency.
A methodology is proposed for the recommendation of minimum discharges for a warm water fishery. This method utilizes field measurements of critical stream areas and biological criteria determined from the used of indicator species. For large rivers, migration and spawning requirements are analyzed using the paddlefish (Polyodon spathula) as the indicator species. For smaller rivers, the suggested indicator species is the sauger (Stizostedion canadense). Rearing flows are determined on the basis of stream productivity by analyzing macroinvertebrate habits, and on the basis of fish habitat typing. The indicator species for determining adequate fish habitat is the stonecat (Notorus flavus).
A number of variables were identified which might require a greater amount of in-stream flow than the fishery, per se. These variables included streamflow needs for riparian and other sub-irrigated vegetation, water quality parameters, anchor ice formation, and the relationship between discharge and sediment yield. Information concerning these variables is insufficient at this time to determine whether a variable will "over-ride" the streamflow requirement for the fishery itself. Further research is needed in these areas, and several investigative methods for conducting such research are proposed.