Understanding the Watershed

What Affects Water Quality?

Water flows into the District from outside jurisdictions
Water flows into the District
from outside jurisdictions

The water in the Potomac River, Anacostia River, and Rock Creek flows into the District from outside jurisdictions. For example, the Potomac River begins in West Virginia, while the Anacostia River begins in Maryland. The quality of water in the District is thus affected by activities throughout the watershed. Storm water runoff from commercial, industrial, residential and agricultural sites, point source pollutants from wastewater treatment plants and industrial discharges, and combined sewer overflows(CSOs) from as far away as West Virginia and Pennsylvania all contribute to the quality of water in the District.

Multiple jurisdictions comprise the watersheds as shown below:

Multiple Jurisdictions Comprise Watersheds: Map
Multiple Jurisdictions Comprise Watersheds: Map
Multiple Jurisdictions Comprise Watersheds: Chart
Multiple Jurisdictions Comprise Watersheds: Chart
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What Are the Water Quality Impacts of CSO?

CSOs can adversely affect the quality of our receiving waters in the following ways:

  • CSOs contain material which contributes to high bacteria levels in the receiving waters;
  • Organic material in CSOs can contribute to low dissolved oxygen levels, which can contribute to a potential for fish stress or fish kills, especially in summer months; and,
  • Debris in CSOs such as plastic bottles, styrofoam cups (otherwise known as "floatables") contribute to poor aesthetics.

DC Water has developed the Clean Rivers Project to control CSOs and improve water quality

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Environment