Four years of water column investigations (1996-2000) bracketed by ongoing interest have identified one or more major new perturbations to the Elkhart Lake Ecosystem. Known factors include establishment ofvigorous zebra mussel populations and occurrence of an unusually strong El Nino-La Nina meteorological event during 1997-1999. Both of these incidents are consistent with some or most of massive observed changes in lake ecology and nutrient cycling. From some points of view, Elkhart Lake has become even more excellent in water quality terms.

The Elkhart Lake Improvement Association proposes to document and quantify the magnitude of inputs and outputs of water and important nutrients to Big Elkhart Lake. Project activities include 1) measuring ground water inflow, 2) measure nutrients in precipitation, 3) measure nutrients in ground water, 4) measure nutrients in intermittent surface water inputs, 5) to install thermistor chain at the deepest sounding of the lake, and 6) to refine mass balance models for the lake.