Total Maximum Daily Load

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The Rappahannock River and Chesapeake Bay regions comprise a complex network of ecosystems which include thousands of miles of rivers, streams, estuaries, and wetlands. Many of these waterways are pristine, healthy and support a wide range of ecosystem services including drinking water supply, recreation, and habitat for fish and wildlife. But there are also many stream and river sections that are considered impaired due to one of many pollutants. These waterways do not provide the minimum designated uses and are then listed as impaired on a national impaired waterways list required by the Clean Water Act.

What is a TMDL?


A Total Maximum Daily Load (TMDL) is a regulatory tool and process that establishes the maximum amount of a pollutant allowed in a waterbody and serves as the starting point for restoring water quality.

A TMDL sets a “pollution diet” specific to a stream or river section that assesses the current level of pollutants of concern and develops a set of strategies for reducing pollutants back to a safe and healthy level.


Why do we have TMDLs?


The goal of the Clean Water Act (CWA) is “to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters“. Under section 303(d) of the CWA, states, territories and authorized tribes are required to develop lists of impaired waters which present a public health risk or do not provide for certain uses like fishing and swimming.

These are waters for which technology-based regulations and other required controls are not stringent enough to meet the water quality standards set by states. The law requires that states establish priority rankings for waters on the lists and develop TMDLs for these waters.

A TMDL includes a calculation of the maximum amount of a pollutant that can be present in a waterbody and still meet water quality standards.

How does a TMDL work?

There are several steps that are included in the TMDL process which generally take multiple years to complete.

  1. Identification of a waterways impairment.
  2. Listing on the 303(d) impaired waterways list
  3. TMDL study and assessment of the waterway by the Virginia Department of Environmental Quality (DEQ)
  4. TMDL Implementation plan developed for the waterway and approved by Environmental Protection Agency.
  5. Installation of recommended projects, programs, and other pollution reduction strategies outlined in the TMDL implementation plan.
  6. Monitoring and assessment.
What are the criteria that causes a waterway to be considered impaired?

To protect human health and aquatic life, states, territories and tribes establish water quality standards. These standards form a legal basis for controlling pollution entering the waters of the United States from a variety of sources (e.g., industrial facilities, wastewater treatment plants, and storm sewers).

If any section of stream, river, lake, estuary, etc is found to not meet the requirements to provide specified designated uses, then it is considered impaired.

These designated uses include:

  1. Protection and propagation of fish, shellfish and wildlife
  2. Recreation
  3. Public drinking water supply
  4. Agricultural, industrial, navigational and other purposes.
Is my local waterway threatened or impaired?

There are a wide ranges of impaired waterways throughout the United States. These impairments range in complexity and threat to public safety, recreation, local economies, and fish and wildlife.

Every two years the Virginia Department of Environmental Quality is required to update a Water Quality Assessment Integrated Report which provides a comprehensive assessment of all waterways throughout the Commonwealth of Virginia. This includes a list of impaired waterways, the cause for the impairment, and the status of a TMDL (if required).

To see if your local waterway has an impairment you can investigate an online interactive map from the Virginia Department of Environmental Quality (DEQ) by Clicking Here (You will need to zoom in five times to then be able to click the 2016 rivers box in the legend).

You can also investigate a broader range of environmental information about your neighborhood or a particular location in Virginia by using the DEQ WHATS IN MY BACKYARD mapping application.

Is the Rappahannock River Impaired?


The Rappahannock River is one of the major tributaries to the Chesapeake Bay and therefore is a contributor of pollution to the Chesapeake Bay. The bay is listed as impaired due to excess Nitrogen, Phosphorus, and Sediments. This means the Rappahannock River is impaired due to these pollutants.

The Rappahannock River also has multiple other impairments for different stretches of the main stem of the Rappahannock River and many of its tributaries. Each of these impairments can be for one of many pollutants and can be in a different stage of the TMDL process.

A complete list of current impairments in the Rappahannock River can be found in the fact sheets of the Virginia 2016 305(b)/303(d) Water Quality Assessment Integrated Report hosted on DEQ’s website.

In this report there is a FACT SHEET for the most impaired waterway sections in the Rappahannock River watershed.

Friends of the Rappahannock is working with our partners to provide information about all waterway impairments in the Rappahannock River Watershed. If you have specific questions about a section of waterway please feel free to Contact Us

Friends of the Rappahannock continues to work with partners throughout the region to address pollution concerns to our waterways and install projects that work to reduce and eliminate those pollutants that threaten the health of the Rappahannock River and Chesapeake Bay. To learn more about our work to reduce pollution please visit our Restoration Program.


Impaired Waterways on the Rappahannock River

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