Total Maximum Daily Load (TMDL)

What is a TMDL?

A Total Maximum Daily Load is a plan of action used to clean up streams that are not meeting water quality standards. The plan includes pollution source identification and strategy development for contaminant source reduction or elimination.

How It Works

Teams of environmental specialists travel throughout West Virginia's watersheds, sampling streams and determining their level of impairment. After a stream is considered impaired and put on the 303(d) list, a TMDL is developed for the stream. The state is divided into 32 major watersheds, which are placed into one of five hydrologic groups (hydrologic groups A - E). Each year, DEP personnel select a watershed(s) from a predetermined hydrologic group to work in and begin the 4-year process of completing a TMDL. Currently, TMDLs are in various stages of development for certain watersheds in Hydrologic Group C, Hydrologic Group D, and Hydrologic Group E.

Why Are TMDLs Necessary?

Public awareness and a desire to control water pollution led to passage of the federal Clean Water Act of 1972. The Clean Water Act established the basis for the regulation of discharging pollutants into streams. Pollution control programs greatly reduced the amount of pollutants that went into streams and navigable waters. Section 303(d) of the Clean Water Act and regulations developed by the U.S. Environmental Protection Agency (EPA), require states to identify all waters that do not meet water quality standards even after pollution controls required by law are in place. Waterbodies not meeting the appropriate water quality standards are considered to be impaired. The impaired segments identified by the states comprise each state's 303(d) list (or Section 303(d) list). The 303(d) list of impaired waters must be submitted to the EPA for review and approval. TMDL's must be developed for all waterbodies on the approved 303(d) list.

On This Page

In the sections below, you will learn more about TMDLs including where WVDEP is currently working, what makes a TMDL necessary, how they are developed, and more.

Contact Us

West Virginia Department of Environmental Protection
Division of Water and Waste Management
Watershed Assessment Branch
601 57th Street SE
Charleston, WV 25304
Phone: (304) 926-0495

Completed TMDLs

West Virginia has worked diligently with the EPA and many other important stakeholders to assure the completion of TMDLs. Choose a watershed below to see completed TMDLs for that watershed. To receive a CD of West Virginia completed TMDLs, call (304) 926-0495.

Hydrologic Group A

Scenic photo of a river.

Group A Watersheds

  • Cheat
  • Shenandoah Jefferson
  • Shenandoah Hardy
  • S. Branch of the Potomac
  • Upper Kanawha
  • Upper Ohio North
  • Youghiogheny

Hydrologic Group B

Underwater picture of a riverbed

Group B Watersheds

  • Coal
  • Elk
  • Lower Kanawha
  • North Branch of the Potomac
  • Tygart Valley

Hydrologic Group C

Underwater picture of a river depicting algae.

Group C Watersheds

  • Gauley
  • Lower Guyandotte
  • Middle Ohio North
  • Middle Ohio South
  • Potomac Direct Drains
  • Tug Fork

Hydrologic Group D

Underwater view of various aquatic plants.

Group D Watersheds

  • Greenbrier
  • James
  • Little Kanawha
  • Lower New
  • Monongahela
  • Upper New

Hydrologic Group E

A muddy river.

Group E Watersheds

  • Big Sandy
  • Cacapon
  • Dunkard
  • Lower Ohio
  • Twelvepole
  • Upper Guyandotte
  • Upper Ohio South
  • West Fork

Where are TMDLs Being Done Now?

In August 2023 WVDEP and contractors started work on Fecal Coliform and pH TMDLs in the Cacapon HUC area including the Lost River, Cacapon River and the Little Cacapon River. In 2022-2023 WVDEP sampled various streams in the Upper Elk watershed and various streams in the Eastern Panhandle. These areas will be included in the 2024 TMDL effort. In July 2023 WVDEP field staff started conducting pre-TMDL monitoring in the Gauley River watershed.

See Also

TMDL Development Timeline

The timeline shown here provides a rough estimate of when major tasks will be completed in TMDL development. While collecting water quality data, field staff will also collect data to characterize sources of pollution. Gathering information from local stakeholders is important to our effort.

Inspector taking a sample  
Sampling near a stream.
An inspector takes a sample from the middle of a creek.  
An environmental specialist takes a sample from the middle of a creek.

Example TMDL Development Timeline

This timeline for the Little Kanawha River Watershed shows the typical process and timings for TMDL development.

Schedule of TMDL Development  
  1. Site Selection: Identified monitoring stations that will characterize water quality in streams.

  2. Pre-TMDL Monitoring: Occurs between July and June each year, timing varies depending upon weather and work loads.

  3. Data Entry and QA/QC: Enters and checks hundreds of data characterizing water quality, aquatic life, and habitat for use in assessments.

  4. Data Assessment: Determines impairment in streams that will be the subject of the TMDL project.

  5. Pollutant Source Investigations: Documents sources that cause or contribute to impairment in streams.

  6. Model Building and TMDL Development: Represents pollutant sources and a range of flow regimes to predict loads at baseline and allocated scenarios.

  7. Draft TMDL to Public: Provides the public an opportunity to review Draft TMDL documents. Comment period lasts for approximately 30 days.

  8. Response to Comments and Revisions: Addresses public and agency concerns.

  9. Presentation of Final TMDL for EPA Approval: Meets programmatic goals and agency requirements.

TMDLs In Depth

Impaired Waters

In a sense, the Water Quality Standards serve as a “measuring stick” to assess the quality of our state’s waters. Section 303(d) of the Clean Water Act and regulations developed by the U.S. Environmental Protection Agency (EPA), require states to identify all waters that do not meet water quality standards even after pollution controls required by law are in place. Streams or lakes not meeting the appropriate water quality standards are considered to be impaired. Every two years, WVDEP publishes a report that contains a list of all streams and lakes in the state that do not meet Water Quality Standards, known as the 303(d) list.

For each water listed as impaired by a pollutant, the Clean Water Act then requires that a TMDL be developed. Full implementation of the TMDL would provide reasonable assurance that the stream or lake will meet Water Quality Standards to restore the designated use.

All streams are placed in a category to describe their status relative to assessment, impairment, and water quality attainment. Category 5 streams are those typically referred to as the “303(d) list”. A few streams are categorized as 4b or 4c and considered impaired, but do not need a TMDL. The WVDEP goal is for more waters to be placed in Categories 1 or 2.

Category Description
Category 1 Waters fully supporting all designated uses.
Category 2 Waters fully supporting some designated uses, but no or insufficient information exists to assess the other designated uses.
Category 3 Water where insufficient or no information exists to determine if any of the uses are being met.
Category 4 Waters that are impaired or threatened but do not need a total maximum daily load (TMDL).
Category 4a Waters that already have an approved TMDL but are still not meeting standards.
Category 4b Waters that have other control mechanisms in place which are reasonably expected to return the water to meeting designated uses.
Category 4c Waters that have been determined to be impaired, but not by a pollutant (e.g. low flow alteration).
Category 5 Waters that have been assessed as impaired and are expected to need a TMDL.
303(d) List Category Description


The map to the right displays impaired waters that need a TMDL and pollutants that have been identified in the 2016 303(d) list. Some waters are impaired for multiple pollutants. The color coded layers denote the various pollutants within the streams. You can click on a specific section of stream to view the particular pollutants within that section.

Pollution Budget

Think of a TMDL as a “Pollution Budget.” If a TMDL is being calculated for a stream, we already know that the stream is impaired because it is receiving too much of a given pollutant. The question then becomes, what sources of the pollutant load have to be reduced – and by how much.

Just as a financial budget analyzes all expenditures and allocates a specific amount of dollars that can be used for each category of expenses, a TMDL analyzes the loading from all known sources of pollution and allocates a specific loading to each category of pollutant sources. TMDLs plan for the elimination of some sources of pollution, such as failing septic systems that discharge untreated sewer into streams, from the budget.

The image shows an aerial view of Parkersburg, WV where the Little Kanawha River confluences with the Ohio River. Land uses, such as urban, residential, industrial, agricultural and forest background contribute pollution to the Little Kanawha River and tributaries. A TMDL will budget loads for these pollutant sources.

Google Earth aerial view of Parkersburg, WV with industrial, forested, residential, agricultural, and urban areas indicated.
Parkersburg, WV

Watershed Management Framework

WVDEP has created a Watershed Management Framework through which programs organize efforts on an established timeline. The TMDL program most often follows those timelines to assess watersheds and develop TMDLs for streams in an entire watershed to be implemented by partnering programs. The state is divided into 32 major USGS HUC8 watersheds, which are placed into one of five hydrologic groups (hydrologic groups A - E).

Each year, WVDEP personnel select one or more watersheds from a predetermined hydrologic group to begin a 4-year process of completing a TMDL. At any given time TMDLs can be in various stages of development for as many as 5 Hydrologic Groups.

List of WV hydrologic groups
Chart of WV Hydrologic Groups

Process For Developing a TMDL

The WVDEP process for developing TMDLs begins with “pre-TMDL” monitoring to collect information about the streams that are impaired in a watershed. Multiple sampling stations are selected within the watershed and sampled monthly by WVDEP for one year. The monthly data are used to assess water quality and to calibrate a computer model used in the TMDL calculation for each stream.

WVDEP gathers available information for the sources of pollution in the watershed. Typical sources include NPDES permits, abandoned mine lands/discharges, mining permits, logging, pipelines, oil and gas well drilling, roads, agriculture/pasture, and residential/urban areas. Once the pollutant source data are complete and the computer model is calibrated, the model predicts instream concentrations of the modeled pollutants (e.g., total iron, dissolved aluminum, fecal coliform bacteria).

Theoretical reductions can then be made in the computer model to predict how much reduction is needed for a stream to attain water quality standards. The percent reduction of the load from different sources of pollution depends upon an allocation approach established by the WVDEP working with point and non-point stakeholder communities.

Stream Representation in Computer Model
Stream Representation in Computer Model

Allocation Strategy

The allocation strategy in West Virginia TMDLs takes a “top-down” approach using a computer model to predict loads from a watershed over different seasons and flow regimes for a six-year time period. Working from the headwaters "top" of a watershed, the model tests if load reductions will result in attainment of water quality standards, then presents a “cumulative load” progressively moving down toward the mouth of the stream. Once the model demonstrates that streams meet specific water quality standards, the percent reductions and final TMDL allocations for each pollutant source result in the final TMDL product. The TMDLs are described in a TMDL public report and support documentation. After sharing the public report and addressing comments, WVDEP sends TMDLs to the USEPA for approval before implementing the TMDLs.

Baseline and Allocated Model Output
Baseline and Allocated Model Output