Title: Determination of Appropriate Lake Water Quality Expectations in Agriculturally Dominated Ecosystems. Phase 1: Defining Nebraska's Hydroecoregions
Project Type: Research
Start Date: 03/01/2006
End Date: 02/28/2007
Congressional District: NE-1
Focus Categories: Surface Water, Nutrients, Agriculture
Keywords: Nutrient Criteria, Watersheds, Reservoirs, Land Use, Agriculture, GIS, Hydrologic Units
Principal Investigators: Holz, Aris Alizbeth; Holz, John Carl; Merchant, James W.
Federal Funds: $ 20,600
Non-Federal Matching Funds: $ 41,289
Abstract: 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 HUC's) 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.
Progress/Completion Report, PDF