Runoff Diversion

The Urban Runoff Diversion System, located immediately adjacent to the north side of Sweetwater Reservoir, captures first flush storm flows and low flow runoff before the water enters Sweetwater Reservoir. When water contains high salt loads (total dissolved solids - TDS) it is diverted downstream into the river, where it joins the underground alluvium and becomes a source of supply for the Richard A. Reynolds Groundwater Desalination Facility. Water with acceptable TDS levels is routed into the reservoir and treated at the Robert A. Perdue Water Treatment Plant.

About the System


The Urban Runoff Diversion System allows Sweetwater Authority to avoid the problem of ever-higher salt levels in Sweetwater Reservoir, thereby providing continued storage capacity and avoiding the need to add more costly treatment at its 30 million gallon per day conventional treatment plant. Net water losses are addressed with the Authority's groundwater desalination facility downstream, which utilizes reverse-osmosis treatment to produce 4 million gallons of drinking water from alluvial and groundwater sources.

Runoff Diversion


  • Average Annual Salts Removed: 535 tons
  • Average Annual Recharge to Lower River Basin:
    • 300 acre feet
    • (97.7 million gallons)
  • System Facilities:
    • Lined Holding 4
    • Total capacity 100 acre-feet (32.6 million gallons)
  • Pipelines:
    • 48-inch by 10,560 feet
    • 27-inch by 10,700 feet
    • 20-inch by 8,000 feet
  • Pump Station: 5,000 gallon per minute capacity
  • Intercept Barrier: 93 feet wide by 10 feet deep (5 feet below ground)
Urban Runoff Diversion System