Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/5/2009
Publication Date: 8/5/2009
Citation: Sadler, E.J. 2009. Lessons Learned from the CEAP Watershed Assessment Studies [abstract]. Science to Solutions Reducing Nutrient Export to the Gulf of Mexico, December 9-11, 2009, Des Moines, Iowa. p. 18.
Technical Abstract: The Conservation Effects Assessment Project (CEAP) has two major components: 1) a National Assessment and 2) a Watershed Assessment Study. The National Assessment is conducted using NRCS data and ARS watershed-scale models to provide estimates of conservation benefits at the national scale. The ARS Watershed Assessment Study (WAS) has since 2003 assessed effects and benefits of conservation practices at the watershed scale. The WAS goals are to provide detailed assessments of conservation programs in a few selected watersheds, a framework for improving the performance of the national assessment models, and support for coordinated research quantifying effects of conservation practices across a range of resource characteristics (e.g. climate, terrain, land use, and soils). The results have advanced our knowledge of how watershed scale assessments can capture impacts at multiple scales. They have also improved our understanding of what conservation practices can and cannot provide beyond the edge of a farm field. Fourteen ARS Benchmark Watersheds support watershed-scale assessment of environmental effects of USDA conservation program implementation. Thirteen of these represent primarily rainfed cropland and one is entirely irrigated. Many contain some areas of grazingland, wetlands, and confined animal feeding operations. Environmental effects and benefits have been estimated primarily for water and soil resources, with some assessment of wildlife habitat and air quality benefits in a few watersheds. The benchmark watersheds and their ARS units are located in Pennsylvania, Maryland, Ohio, Indiana, Georgia, Iowa, Missouri, Mississippi, Oklahoma, Texas, and Idaho, with modeling research being conducted in Colorado and Oregon. Of these, the Ohio, Iowa, Missouri, Mississippi, and Oklahoma watersheds drain into the Mississippi River and are thus directly relevant to the Gulf Hypoxia theme of this conference. The Indiana watershed drains to Lake Erie, but represents the conditions in southern Indiana that are within the Mississippi River Basin (MRB). Likewise, much of the research in other watersheds has also provided results that are applicable to the MRB. While it may not be the most earth-shattering finding, the CEAP results to date illustrate how critical it is to fully understand the system being considered for conservation practices. Furthermore, as there are a number of potential contaminants, BMP choices must be balanced among them and accommodate the complex, dynamic environmental interactions associated with each site. Often, we have observed that BMPs implemented for and successful in mitigating one environmental concern have caused an unintended increase in offsite effects of another contaminant. Changing public interests and knowledge have prompted re-interpretations of some research and asked questions that must be pursued using different experimental designs. To fully measure environmental effects of a BMP, we need to know information about flow, sediment, nutrients, and sometimes pesticides, pathogens, and emerging issues such as antibiotics and endocrine disruptors. It is also important to recognize what producers have already done and what limitations (e.g. time, labor, economic) they face. One example of the complexity of BMP interactions is provided by the Iowa watershed studies. In the South Fork of the Iowa River, they found that during the past 150 years, an average of 2.6 feet of sediment had been deposited in the floodplain affecting an area up to 260 feet wide. This deposition and concurrent loss of floodplain storage likely causes higher stages and exacerbated flooding. Furthermore, channel straightening increases flow velocity and exacerbates bank erosion. Another study showed distinguishable land use (watershed treatment) and climate trends (time) through simultaneous shifts in how energy (evaporativ