Rehabilitating the aquatic ecosystem of Rainy Lake and Namakan Reservoir by restoration of a more natural hydrologic regime

Regulation has altered the magnitude and timing of water level fluctuations and has removed much of the hydrologic variability the lakes would experience under natural conditions. The controlled water levels adversely affect key elements of the aquatic ecosystem: littoral vegetation, benthic organisms, fish, aquatic birds, and furbearers. Specific water levels, particularly spawning season levels, and annual fluctuations of water levels influence fish densities and spawning success. Phytoplankton biomass and primary production may also be affected by the regulatory program. Alternative water level regulations were developed by various user groups. Regulations that emulate natural fluctuations in water levels, may overcome the adverse biological effects of the present program. Whereas conflicting needs of water users may prevent implementation of such alternatives and may preclude complete restoration of the Rainy Lake-Namakan Reservoir system, a regulatory program that is more ecologically sound seems possible. -from Authors