Water Resources Research Act Program

Details for Project ID 2006NE128B

Determination of Appropriate Lake Water Quality Expectations in Agriculturally Dominated Ecosystems. Phase 1: Defining Nebraskas Hydroecoregions

Institute: Nebraska
Year Established: 2006 Start Date: 2006-03-01 End Date: 2007-05-01
Total Federal Funds: $20,600 Total Non-Federal Funds: $41,289

Principal Investigators: Aris Holz, John Holz

Project Summary: Reservoir classes have been developed in Nebraska utilizing a novel ecological continuum approach appropriate for grouping water bodies with similar water quality potential. Once lake classes were identified, the USEPA 25th percentile approach was used to identify the best 25% of lakes, which were used to establish nutrient benchmarks (reference conditions) for members of a lake class. Unfortunately, there are nearly 500 additional reservoirs that remain to be classified in the state, which would require significant funds and would likely take over a decade. In addition, this approach is recommended for regions where some lakes are impacted by anthropogenic disturbances. Clearly, the approach may not be optimal in agricultural regions where nearly all lakes are heavily impacted by land-use as the relative contributions of land-use (e.g., agriculture) and natural processes to the lake nutrient concentrations have not been determined and thus make the values highly artificial. However, geographic areas such as watersheds are known to be strongly correlated with reservoir water quality in Nebraska and we propose to develop a strategy for grouping geographic regions (i.e. 8 or 11 digit HUCs) with similar landscape characteristics into management groups (termed hydroecoregions) by using Nebraska as a model for agricultural ecosystems. Agricultural land-use data will not be used to define the hydroecoregions, resulting in a representation of geographic regions unaltered by anthropogenic disturbances. This critical first step will facilitate subsequent research that will build and calibrate integrated models of agricultural watersheds and lake water quality for each hydroecoregion. These models will allow the determination of appropriate water quality expectations under various best management scenarios in order to identify more appropriate water quality goals.