River Basin Characteristics
The 771-square-mile Blanchard River Watershed is located in northwestern Ohio. The Blanchard River is a tributary of the Auglaize River, which drains into the Maumee River and eventually into Lake Erie near Toledo. In general, the watershed is flat with 83 percent of the watershed having slopes of less than 2 percent. Soils within the western portion of the watershed are nearly level glacial lake plain with some scattered ridges of sandy soils. The headwaters of the Blanchard River are in the southeast corner of the watershed. The river flows north and then turns west, just upstream of Findlay. Major tributaries of the Blanchard River include Cranberry Creek, Riley Creek, Ottawa Creek, Eagle Creek, Lye Creek, and The Outlet.
Prior to historical settlement, an estimated 42 percent of the watershed was covered in wetlands but the majority of wetlands were drained and converted to agricultural lands in the early 1900s. Currently land use in the Blanchard Watershed is estimated to be 80.8 percent cultivated crops (mostly corn, soybeans, wheat and hay), 10.1 percent developed, 5.6 percent forest, 2.6 percent pasture and grassland, and < 1 percent open water and wetlands. The largest community within the watershed is Findlay with a population of approximately 45,000. From 1982 to 1997, the urban land in the watershed increased by 175 percent.
Primary causes of impairment include habitat/flow alteration, siltation, organic enrichment, low oxygen, nutrient enrichment, and excess ammonia. Nutrient impairments have been attributed to loads from agricultural areas, unsewered areas, and small wastewater treatment plants. Since 2001, wastewater treatment plant upgrades have been implemented for the Findlay and Bluffton wastewater treatment plants. Conservation tillage is practiced on 46 percent of the cultivated cropland within the watershed; however, the Blanchard River Watershed ranks last in percentage of conservation tillage as compared with the other seven watersheds within the Western Lake Erie Basin (WLEB).
For this project, the Agricultural Non-Point Source (AGNPS) suite of models were applied to determine sediment sources, contributing locations, and the effect of best management practices (BMPs) on rates of sediment delivery to the mouth of the watershed.
The watershed was represented in the model using data from several sources. Spatial information and attribute data from SSURGO and NASIS databases were used to define soil conditions. Stream channel geometry was based on a collection of surveyed cross-sections in the Blanchard and neighboring watersheds. A four-year crop and tillage rotation data layer was developed based on remote sensing data. Crop land management practices and fertilizer/manure application rates were defined in the model based on local knowledge. Point source loads from 13 permitted discharges were also included.
The model was calibrated against observed stream flow and water quality data for the period from 2002-2009 and a model confirmation was also conducted using best available data from 1995-2001. A set of land management alternatives were run including tile drain management, conservation tillage, cover crops, conversion of crops to grassland, and improved nutrient management. A pre-settlement “all natural” watershed scenario was also developed. The simulation of nutrient loading from the watershed under most management scenarios was informational; however, model nutrient calculations related to conversion of cropland to non-cropland land uses were problematic.
Use and Applications
The goal of the modeling effort was to predict direct runoff as well as sediment and nutrient loading from the highly agricultural watershed. A set of potential land management alternatives were evaluated to estimate the potential benefits in terms of reduced sediment and nutrient loading. This modeling exercise was a successful attempt at quantifying direct runoff and suspended sediment loading contributions from the Blanchard River watershed under baseline and potential management scenarios.
This modeling effort will support local stakeholders in identifying sources of sedimentation and excess nutrients throughout the watershed. The Blanchard River watershed model will: 1) Simulate erosion, sediment delivery pathways and sediment delivery yields and loads in the watershed; 2) Simulate fate and transport of nutrients throughout the watershed; 3) Project the potential benefits of conservation treatment strategies and best management practices and; 4) Support the larger GLRI effort by reducing erosion in the Maumee Basin and reduce sediment and associated nutrient delivery to Toledo Harbor and Lake Erie.
- U.S. Army Corps of Engineers – Engineering Research and Development Center
- U.S. Department of Agriculture
- University of Toledo
- Heidelberg University
- U.S. Geological Survey
For More Information
USACE, Buffalo District
1776 Niagara Street
Buffalo, NY 14207
Phone: (716) 879-4488