Location: Soil Drainage Research2010 Annual Report
1a. Objectives (from AD-416)
1. Measure and quantify water quality, water quantity, and soil quality effects of innovative conservation and source water protection practices as well as different land use management at the field, farm, and watershed scale for the Upper Big Walnut Creek and other appropriate watersheds. 2. Develop and validate watershed scale water quality models and quantify the uncertainties of model predictions at field, farm, and watershed scales for the Upper Big Walnut Creek and other appropriate watersheds. 3. Develop models and decision support tools to determine the efficacy of management and land use options under conditions of changing climate.
1b. Approach (from AD-416)
Quantify the influence of conservation practices and land use on the water chemistry and hydrology of agricultural drainage ditches and streams in the Upper Big Walnut Creek watershed using a before-after-control-impact (BACI) paired watershed design. Two pairs of watersheds, one pair characterized as drainage ditches and one pair characterized as streams, have been identified and instrumented with flumes and automated samplers. Discharge and water samples will be collected automatically via Isco equipment. To quantify how much the loading to headwater streams is reduced by watershed scale adoption of nutrient and pesticide management practices, water samples will be collected using both time and flow proportional sampling. The samples will be analyzed for nutrients using colorimetric flow injection analysis and for pesticides using gas chromatography and ELISA. Apply a calibrated watershed scale model to aid selection, placement and extent of BMPs. Determine the impact of conservation practices on aquatic communities in lotic ecosystems by measuring and quantifing in-stream habitat (water depth, velocity, wet width, and substrate types), in situ water chemistry measurements (dissolved oxygen, pH, conductivity, water temperature), and aquatic communities in each site three times a year in the spring, summer, and fall for the duration of the study. Conduct field experiments to determine the influence of herbaceous riparian buffers on the physical habitat and aquatic communities in agricultural drainage ditches. Geomorphology and riparian habitat will be sampled once a year, while in-stream habitat, water chemistry, and aquatic communities will be sampled at least three times a year for two years. Laboratory, field, and modeling approaches will be used to assess and characterize the environmental aspects of urban and golf course turf, including the development and evaluation of management strategies and/or technologies. Before – after watershed scale studies will be used to quantify the fate and transport as well as aid in the determination of the processes and management controlling the fate and transport of nutrients, pesticides, and sediment from turf environments and urban landscapes. Laboratory studies, replicated plots, and paired field sites will be used to evaluate innovative technologies, strategies and/or management practices.
3. Progress Report
The Soil Drainage Research Unit (SDRU) continues to make advances in quantifying the watershed scale environmental and economic impacts of conservation practices as well as assessing and characterizing the environmental aspects of managed turf. The Upper Big Walnut Creek (UBWC) watershed in Ohio is one of 14 benchmark watersheds identified in the Conservation Effects Assessment Project (CEAP) to provide detailed assessments of watershed scale implementation of conservation practices. Within the UBWC watershed, data was collected at 46 nested and paired sites representing surface and subsurface discharge, channelized and unchannelized watersheds, agricultural and urban land uses, and forested and herbaceous riparian buffer areas. These sites are representative of agricultural and urban areas in the Eastern Corn Belt and will aid in answering a variety of environmental and economic questions related to the watershed scale impacts of conservation practices. To date, three years of baseline data and two and one half years of treatment data (precision nutrient management or pesticide management) have been collected from the paired watersheds. Quantification of the impacts of those practices is ongoing. Progress continues on assessing the impacts of herbaceous riparian buffers on fish communities. A hydrologic assessment of different headwater streams within the UBWC watershed was completed. The results highlight the seasonal differences in magnitudes, frequency, and rates of change in headwater hydrology. SDRU scientists collaborated with scientists from Indiana University-Purdue University Fort Wayne to investigate the impacts of agricultural drainage ditches on aquatic ecology. The SDRU continues to make progress toward assessing and understanding the environmental role of various watershed scale landscapes in the urban to rural gradient within UBWC. Progress continues to be made on the development and assessment of inline filters designed to clean drainage waters. A Category II scientist was hired to lead this research thrust and is making positive progress in the identification of materials and delivery systems to treat flow rates expected from agricultural tile drainage. The SDRU through the Delaware Soil and Water Conservation District and Environmental Defense Fund was successful in obtaining a Mississippi River Basin Initiative grant that will facilitate Upper Big Walnut Creek (UBWC) watershed scale implementation of conservation practices for assessment.
1. Documented public health risks posed by channelized headwater streams. Public health issues related to channelized headwater streams that are common throughout the midwestern United States have not been explored. ARS scientists from Columbus, Ohio documented the public health risks posed by channelized headwater streams by comparing water chemistry and the larval abundances of potential insect disease vectors between channelized and unchannelized headwater streams within central Ohio. Concentrations of commonly occurring nutrients and pesticides was often greater in channelized headwater streams and exceeded national drinking water standards more often. Potential insect vectors of the West Nile virus, Lacrosse encephalitis, St. Louis encephalitis, and Eastern Equine encephalitis constituted a small fraction of the overall larval insect captures and abundances did not differ between stream types. These results suggest that management of channelized headwater streams may be necessary to reduce the public health risks related to the downstream transport of agricultural nutrients and pesticides. Specifically, agricultural conservation practices capable of reducing nutrient and pesticide loads within channelized headwater streams may assist with the protection of downstream surface drinking water sources. These results also suggest headwater streams in general may not serve as a significant source of potential disease vectors and insecticide application and channelizing these streams for larval mosquito control does not appear to be warranted.
2. Determined the feasibility of an end-of-tile filter approach to reduce nutrient and pesticide transport via subsurface drainage. Subsurface drainage is a necessity for crop production agriculture in humid climates with poorly drained soils. In excess of 20.6 million ha (37%) of the tillable acres in the Midwest are managed with subsurface tile. While partially responsible for consistent high crop production yields, subsurface tile drainage has been recognized as a primary source of agricultural nutrient transport to streams and waterbodies to which they discharge. ARS scientists in cooperation with United States Golf Association (USGA) personnel investigated the feasibility of an end-of-tile filter for treating subsurface drainage waters. The findings suggest that the end-of-tile filter approach could be adapted as a best management practice to reduce nutrient and pesticide transport in subsurface tile drainage where the contributing area and flow rates are relatively small. Additionally, the findings support further investigation into alternative sorbent materials and delivery designs that permit larger drainage areas and greater flow rates to be filtered. The beneficiaries of this research are all downstream water users that use surface water for drinking, recreation, and navigation.
3. Developed baseline water quality signatures from various landscapes (urban, agriculture, turf) within an urban to rural gradient. Significant amounts of agricultural lands within the Upper Big Walnut Creek watershed are being lost annually to urban development. Understanding the role of each landuse within the watershed is critical to the development, placement, and assessment of best management practices (BMPs) aimed at reducing and mitigating nonpoint source pollution. ARS scientists in cooperation with Soil and Water Conservation District (SWCD) and Natural Resource Conservation Service (NRCS) personnel and UBWC landowners and operators measured water quality signatures from different landuses. Within the Upper Big Walnut Creek (UBWC) watershed, datasets have been assembled for agriculture, urban, and turf landscape classifications. The results suggest that nitrogen is primarily a result of agricultural activities; however, phosphorus contributions are more evenly distributed from across landuses. These datasets will provide state, federal, and private entities a “measuring stick” for assessing the impacts of implementing BMPs across the watershed.
4. Examined influence of riparian habitat type on aquatic community colonization. Previous studies have not examined aquatic community colonization within riparian zones of agricultural headwater streams. Understanding how aquatic community colonization differs between channelized and unchannelized streams is needed to assist with developing riparian management guidelines for these small streams. An ARS scientist and student intern from the Ohio State University evaluated if aquatic community colonization within riparian zones of headwater agricultural streams is influenced by stream channelization. Macroinvertebrate abundance, taxa richness, and relative abundances of mosquitoes, dipterans, and crustaceans were greater within experimental mesocosms placed in the riparian zones of unchannelized headwater streams than channelized headwater streams. These results suggest stream channelization reduces aquatic community diversity and abundance in riparian zones of headwater agricultural streams. This information can be used by state, federal, and private agencies responsible for managing agricultural watersheds and restoring streams.Smiley, P.C., King, K.W., Fausey, N.R. 2010. Public Health Perspectives of Channelized and Unchannelized Headwater Streams in Central Ohio: A Case Study. Journal of Water and Health. 8:577-592.