Lake James’ water quality normally is good to excellent. But during storms the inflowing streams and rivers become silty, which smothers fish habitat, carries contaminants downstream and gradually fills in the lake. Silt is a wide-spread pollutant that has increased as development has exposed more soil to erosion and created more impervious surfaces (e.g., roofs, roads, parking lots, etc.). These surfaces shed water quickly rather than letting it soak into the soil. This leads to surges known as “first flush,” that wash urban pollutants (e.g., fuel, oil, rubber tire particles, exhaust fumes, etc.) into storm water, then into drainage ditches and storm sewers. Subsequently, the storm water flows into streams and rivers, where soil is scoured from the beds and banks by rushing water, carrying the pollutants downstream.

(See silt bed photos below, taken during low water – Aerial photo opportunity provided by SouthWings)

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Responding to these threats, LJEA has undertaken a multi-year program to reduce erosion and silt effects on the lake and its watershed.
The objectives of this program are to:
1.     Determine how much silt has accumulated in the lake since it was created and where it is located
2.     Estimate the rate of silt accumulation
3.     Identify the key sources of silt
4.     Pursue prevention and mitigation programs through education and remediation
5.     Periodically gauge progress by reassessing the amount and location of silt deposits in the lake, which shift over                time
Three related projects address these objectives:

  1. Bottom Mapping
  2. Educational Materials
  3. Silt Sources

The relationships among these projects are illustrated below:


Bottom Mapping Project

This project addresses the current location of silt deposits. A generous grant from the Rostan Family Foundation enabled LJEA to purchase sonar, GPS, computer equipment and software necessary to map the silt deposits in Lake James.
This networked equipment provides real-time location and depth information. Utilizing Dr. Depth©  tracking-plotting software, the system tracks and displays depth and GPS readings as they are taken and then converts the results to 2 and 3-dimensional plots. (See examples below.)
The picture below is a colored, test Lake Bottom Mapping superimposed on a Google Earth photo of Lake James between Lake Club Point and Old Wildlife Development.
Red is shallow; Blue is deep

Educational Materials Project

The aim of second project is to prevent erosion and siltation through education of land owners, developers, school children, etc. Related sub-projects are researching and designing printed materials.

  1. Summarizing state and local requirements that must be met when more than an acre of land is disturbed for development purposes, and
  2. Describing Best Practices to prevent erosion and sedimentation when land is disturbed.

Silt Sources Project

The purpose of the third project is to find the key sites of erosion that produce silt in the watershed that ultimately affects Lake James. Teams have been created to go out during storms and document where the main silt sources are located.  This is largely a backtracking process, following muddy waters upstream to their sources and recording their appearance, location, etc.
With this information in hand, the intent is to help landowners stop the loss of their land due to erosion, stabilize their soil through mitigation projects and perhaps protect their vulnerable sites with conservation easements that stop erosion and reduce property tax on the protected land.