The Coles Creek Watershed is in St. Lawrence County, New York ranging from the Coles Creek State Park in the north and between Highway 345 and Grass River in the south. A majority of the land use is categorized as woody wetlands (swamp), accounting for 33 percent of the watershed. Deciduous and evergreen forest also make up a large portion of the area. Additionally, 13 percent of the watershed is dedicated to generalized agriculture and pasture.
The agricultural fields in the northern portion of the watershed show higher erosion potential. There are minimal to no buffer zones or wooded riparian areas along the channel in this part of the watershed. Therefore, the potential for sediment loading to the stream is greater.
The topography of the area is generally flat, with areas of ponding water behind highway and railroad embankments; these areas are acting as in-stream sediment traps. Stream channels are not a significant source of sediment supply, but the few clear-cut areas are a source of sediment supply.
Buffer zones along stream channels and riparian wooded zones are being used in addition to other Best Management Practice (BMP) techniques such as contour plowing. Rock barriers and small swales are being utilized to reduce velocities and to allow sediment to settle out.
The Coles Creek Sediment Transport Analysis and Regional Training (START) Assessment was used to demonstrate the use of web-based tools for determining potential areas of erosion and sediment supply and transport within the watershed.
The START Assessment used the High Impact Targeting (HIT) tool, the Long-Term Hydrologic Impact Assessment Low Impact Development (L-THIA LID) tool, and the Web-based Water Erosion Prediction Project (WEPP) model. Each tool was used independently of the others and provided results used to assist in prioritizing areas of erosion potential.
HIT is a decision support tool for multi-scale prioritization of agricultural areas that combines an erosion model and a sediment delivery model to calculate annual erosion and sediment loading in watersheds.
L-THIA LID is a decision support tool that evaluates the benefits of low-impact development practices by producing existing runoff depth and volume along with nonpoint source pollution loading.
The WEPP Watershed Online GIS Interface is a small-watershed scale model developed to quantify the impact of land management practices in watersheds and identifying problematic areas.
Additionally, field reconnaissance was used to better understand watershed characteristics and allowed researchers to cover areas not included in the on-line tools. Results from the on-line tools and field reconnaissance were overlaid on a watershed map.
Use and Application
The purpose of this START Assessment was to demonstrate the use of the available on-line tools and provide a basis for further studies of watersheds. The assessment was prepared for the St. Lawrence County Soil and Water Conservation District in Canton, New York.
Areas of concern regarding potential of erosion and sediment supply locations were identified from the results of the assessment. The online tools and procedures described in this assessment can be used to refine areas of potential erosion and to compare results of certain BMPs within the watershed.
The tools used in this assessment are available to local stakeholders to evaluate management options for the watershed with the overall goal of reducing the loading of sediments and pollutants to tributaries in order to enhance Great Lakes water quality, delist Areas of Concern, and reduce the need for navigation dredging.
- U.S. Army Corps of Engineers, Buffalo District
- St. Lawrence County Soil and Water Conservation District
- Institute of Water Research, Michigan State University