Sources of Pollution

The main goal of the watershed plan is to reduce the number of bacteria and turbidity impairments across the Edisto Island watershed so that waterways meet state water quality standards, and all shellfish areas are open to recreational and commercial harvest. To achieve this goal, we needed to identify the main causes and sources of pollution. 

Our assessment of the watershed identified the most probable sources of bacteria pollution as: 

1. Failing or poorly functioning septic systems 

2. Discharges of untreated or partially treated wastewater from boats 

3. Waste from livestock, dogs, and wildlife 

4. Stormwater discharges from detention ponds and ditches

Wastewater treatment on Edisto Island is primarily achieved through on-site wastewater treatment systems, also known as septic systems or septic tanks. Edisto Beach has a municipal wastewater treatment plant that services roughly half of the properties on Edisto Beach, but the other half of the properties are served by septic systems. Many of these systems are aging, poorly functioning, located on soils that are no longer well-drained, and at risk of flooding during storms. Promoting regular maintenance of septic systems, and identifying and assisting households that need replacementments will be a key part of improving water quality.

South Carolina’s estuarine waters are considered to be naturally higher in sediment than many other states. Additionally, excess nutrients in waterways can stimulate the growth of algae in waterways, which can also increase the turbidity (cloudiness) of water.

Our assessment of the watershed identified the most probable sources of turbidity as: 

1. Streambank erosion 

2. Construction and other land clearing 

3. Cropland and pasture erosion 

4. Stormwater pond bank erosion 

5. Roads 

6. Urban runoff 

7. Excess nutrients