ARS | Publication request: Overview of the Mark Twain Lake/salt River Basin Conservation Effects Assessment Project

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 19, 2007
Publication Date: November 1, 2008
Citation: Lerch, R.N., Sadler, E.J., Kitchen, N.R., Sudduth, K.A., Kremer, R.J., Myers, D.B., Baffaut, C., Anderson, S.A., Lin, C. 2008. Overview of the Mark Twain Lake/Salt River basin Conservation Effects Assessment Project. Journal of Soil and Water Conservation. 63(6):345-359.

Interpretive Summary: The Mark Twain Lake/Salt River Basin was selected as one of 12 USDA-Agricultural Research Service benchmark watersheds for the Conservation Effects Assessment Project (CEAP) because of documented soil and water quality problems and broad stakeholder interest. The basin is located in northeastern Missouri within the Central Claypan Region, and it is the source of water to Mark Twain Lake, the major public water supply in the region. The basin is characterized by flat to gently rolling topography with a predominance of claypan soils that result in high runoff potential. The claypan soils are especially vulnerable to soil erosion, which has degraded soil and water quality throughout the basin, and to losses of herbicides that contaminate streams and lakes. Results from studies of best management practices (BMPs) showed that no-till cropping systems did not reduce surface runoff compared to tilled systems and led to increased transport of soil-applied herbicides. A major challenge is the need to develop cropping systems that incorporate herbicides yet maintain sufficient crop residue cover to control soil erosion. Preliminary results of computer model simulations showed that the Soil and Water Assessment Tool (SWAT) model was capable of predicting observed long-term trends in atrazine concentrations and the impact of grass waterways on atrazine concentrations in Goodwater Creek, a small sub-watershed within the basin. Current and future research efforts will continue to focus on BMP studies, development of needed tools to improve watershed management, and refinements in the calibration and validation of the SWAT model. This research will benefit the USDA-NRCS and other customers (e.g., Missouri Departments of Conservation and Natural Resources) by: 1) creating a publicly available database of water quality results; 2) quantifying the effects of conservation practices on loading of N, P, sediment, and herbicides to streams within the basin; 3) providing design criteria for implementation of vegetative buffers; and 4) providing a validated SWAT decision support system for the basin.

Technical Abstract: The Mark Twain Lake/Salt River Basin was selected as one of 12 USDA-Agricultural Research Service benchmark watersheds for the Conservation Effects Assessment Project (CEAP) because of documented soil and water quality problems and broad stakeholder interest. The basin is located in northeastern Missouri within the Central Claypan Region, and it is the source of water to Mark Twain Lake, the major public water supply in the region. At the outlet to Mark Twain Lake, the basin drains 6417 km2 (2478 mi2), including 10 major watersheds that range in area from 271 to 1579 km2 (105 to 609 mi2). The basin is characterized by flat to gently rolling topography with a predominance of claypan soils that result in high runoff potential. The claypan soils are especially vulnerable to soil erosion, which has degraded soil and water quality throughout the basin, and to surface transport of herbicides. Results from cropping system BMP studies showed that no-till cropping systems did not reduce surface runoff compared to tilled systems and led to increased transport of soil-applied herbicides. A major challenge is the need to develop cropping systems that incorporate herbicides yet maintain sufficient crop residue cover to control soil erosion. Preliminary results of SWAT model simulations showed that the model was capable of simulating observed long-term trends in atrazine concentrations and loads and the impact of grass waterways on atrazine concentrations. Current and future research efforts will continue to focus on BMP studies, development of needed tools to improve watershed management, and refinements in the calibration and validation of the SWAT model.