Measuring the Contribution of Agricultural Conservation Practices to Observed Trends and Recent Condition in Water Quality Indicators in Ohio, USA.

Over the last three decades, significant investments made to upgrade wastewater infrastructure and manage pollution from diffuse sources have resulted in measurably improved water quality and biological conditions in Ohio's rivers and streams. Conservation measures to reduce soil loss appear to have contributed significantly to the improvement witnessed over the last two decades and should therefore be continued. Within the most recent timeframe examined, little difference was found in either total phosphorus or suspended sediment concentration in relation to conservation measures, indicating that the environmental benefits of measures targeting soil loss may be approaching an asymptote. Conservation measures targeting livestock and forage management, however, appear to have reduced nitrogen concentrations within the recent time frame. An examination of the interrelationships between habitat quality, conservation measures, and land use indicated that water quality was generally mediated by interactions with stream habitat quality. However, the positive effect of habitat quality was reduced in catchments draining fine-textured soils. The implication of these latter two findings suggest that proscriptively adding natural function to the large network of ditched and maintained conveyances draining agricultural lands would substantially improve water quality, but management at the field level is necessary to minimize phosphorus losses.