Northern Prairie Wildlife Research Center
Department of Fisheries and Wildlife, Utah State University, UMC-5210, Logan, UT 84322-5210
Surface water and pore water concentrations of dissolved nutrients in 10 diked and 2 undiked marshes were monitored during a series of planned water level changes during 1980-89. Water level changes had little effect on surface water concentrations, but showed some evaporative concentration in low water marshes. Deep water marshes had greater water through-flow due to dike seepage. Concentrations of most surface water ions were close to those in the undiked marshes. Deep flooding increased the forms of N and P in pore water, which then decreased during drawdown. Annual changes were often large, but similar, in diked and undiked marshes. They were apparently not the result of the planned water-level fluctuations.