Saving the Occoquan Reservoir

Prince William County is considering instituting restrictions in an Occoquan Overlay District. How this planning tool is used and implemented will have long term consequences for the Occoquan Reservoir and our drinking water supply. Fairfax Water supplies drinking water to around two million people in Fairfax County, Loudoun County and Prince William County. An essential portion of the Fairfax Water supply especially during times of drought is the Occoquan Reservoir which supplies the source water to the Griffith water treatment plant. The Occoquan Reservoir holds 8.3 billion gallons of water.

When the Occoquan Reservoir was first built 1957 it was located in a rural and forested area and the water was pristine. Now, however; the Occoquan Reservoir is under threat from the urbanization of the region. Pollution from runoff, called non-point source pollution is threatening the health of the Occoquan Reservoir and our drinking water supply.

Non-point source pollution is fertilizer and herbicides from agricultural land and suburban lawns. The largest crop in Virginia is suburban lawns. Pollution form urban and suburban stormwater runoff carrying oil, grease, solvents and tire rubber; septic systems, pet and recreational animal waste bacteria, nutrients and sediment from improperly managed landscaping; and finally, salt.

Development increases impervious surface area. The physical condition of the Watershed's tributaries has been measured to fall with development. Increased stormwater runoff from impervious surfaces flows into streams and creeks at a higher volume and velocity. The result is increased erosion of stream banks that leaves a degraded ecosystem. However, these roads, sidewalks, parking lots all have to be cleared of snow and ice. Over time this has meant an increasing level of salt.

 According to the Virginia Department of the Environment (DEQ) analyses from three different studies at multiple locations have found increasing freshwater salinization in Northern Virginia. According to Fairfax Water, salt contamination in the source water is becoming a generational problem.

from Fairfax Water presentation

While salts are very effective at deicing roads, when the snow or sleet melts the salts are washed off into local waterways or seep through soils into groundwater systems with negative impacts on water quality and the environment. Salts pollute drinking water sources and are very costly to remove. The current water treatment plants cannot remove the salt. The only available technology to remove salt from the source water is reverse osmosis which is cost prohibitive and requires a significant amount of energy to run. This will significantly increase the cost of water in the region.

Planning to protect the Occoquan Reservoir is planning to maintain forested areas, not build more roads, homes or businesses in the Occoquan Reservoir. If we fail to plan for the future and protect the Occoquan Watershed and source water we will have failed the next generation.  To learn more watchthe linked video of Greg Prelewicz and Nicki Bellezza from Fairfax Watertalking about water supply and water protection in the Occoquan Watershed andthe Occoquan Overlay District under consideration in Prince William County.