Lake Springfield Watershed Streambank Erosion Assessment

Synopsis

No direct assessment of streambanks has been completed for the Lake Springfield watershed. Localized areas of severe bank erosion are thought to exist despite the fact that cursory estimates indicate that streambank erosion comprises a relatively low contribution of the overall sediment and nutrient load to the lake. Northwater was retained to address data gaps relating to streambank erosion by updating current estimates of loading and severity and identifying project opportunities through a direct assessment.

Client(s):

Sangamon County Soil & Water Conservation District
Completion Date:

2018
Services:

Water Resources, Water Supply
Market/Sector:

Government
Location:

Sangamon County, Illinois

Project Description

Staff from Northwater directly assessed over 40 miles of streams in the 160,000-acre Lake Springfield watershed. The project was needed due to limited knowledge on the extent and severity of bank erosion, a lack of where project opportunities might exist, and a need to understand if previous estimates accurately portrayed sediment and nutrient loading.

Using GPS technology, Northwater collected reach-level data representing eroding bank height, lateral recession rates, pollution sources, project opportunities, buffer quality, and other unique stream characteristics. Field data was transferred to GIS, used to quantify sediment and nutrient loading and produce a detailed map atlas representing erosion severity, stream buffers, unique features, and practice recommendations.

New estimates suggested that streambank erosion is responsible for approximately 3.7% of the total sediment load to Lake Springfield, slightly lower than previously thought.