Frequently Asked Questions about TMDLs


TMDL Development

Total Maximum Daily Load (TMDL) is a term used to describe the amount of pollution a stream can receive and still meet water quality standards. Water quality standards are regulations based on federal or state law that set numeric or narrative limits on pollutants. TMDLs are required for water bodies that are determined to be impaired. The Virginia TMDL program was historically governed by a federal court order Consent Decree that laid out a schedule for TMDL development through 2010 for waters identified as impaired by 1998. For all other water bodies, TMDL development is generally scheduled within 8-12 years of finding the water body impaired.

What are the mandated elements of a TMDL?

A TMDL is required under the Clean Water Act and its implementing regulations to contain the following 8 elements:

  • be developed to meet the applicable water quality standard
  • contain a waste load allocation for permitted point sources, and nonpoint sources (NPS)
  • contain a margin of safety to account for uncertainties in TMDL development
  • be developed for critical stream conditions
  • consider seasonal variation
  • consider background contributions
  • be subject to public participation, and
  • contain reasonable assurances for implementation of nonpoint source load allocations.

What is the purpose of a TMDL Study?

A TMDL Study identifies sources of pollution and reductions needed to attain water quality standards. A TMDL considers point sources such as residential, municipal, or industrial discharges and non-point sources such as residential, urban, or agricultural runoff. Virginia's goal is that all streams attain the appropriate beneficial uses. These beneficial uses are described by the following use goals: drinking water use, swimming use, fishing use, shellfishing use, and aquatic life use. These uses are protected by application of the state's numeric and narrative water quality criteria.

How does Virginia determine what is an 'Impaired Water'?

Through water quality monitoring and assessment (= comparing the monitoring data to the applicable water quality standards), the Virginia Department of Environmental Quality (DEQ) determines whether a water body is impaired or not. Virginia periodically submits a list of the waters found to be impaired, the so-called 303(d) list of impaired waters, to the Environmental Protection Agency. Based on the 2002 303(d) list, approximately 1,450 waters are impaired statewide. Most impaired waters require TMDLs.

How will the public participate in TMDL development?

A series of meetings will be held. The first meeting will inform the public about the impairment, the TMDL process, and obtain public comment. Any subsequent meetings will discuss the on-going TMDL study, including identification of pollutant sources and the TMDL development method. Additional small meetings may be held with stakeholders to ensure the information used in the study is accurate. The final meeting will present the draft TMDL study, including pollutant reduction targets, for public review and comment prior to submittal to EPA. Public meetings will be advertised in local newspapers, through direct mailings, and in the Virginia Register.

What kind of input can stakeholders provide during the process?

Public participation is important because landowners know much of the information needed to help clean up the stream. Such information can be the location of public sewers, septic systems and straight pipes as well as the condition of the septic systems. Other information can be the confirmation of livestock and wildlife numbers and locations in the area, or the identification of additional data sources. Stakeholders are encouraged to provide input into the study process so that the final report is as accurate as possible.

What happens after the TMDL Study is complete?

The TMDL Study will be submitted to EPA which will have 30 days to review and approve the TMDL. Then a TMDL Implementation Plan (TMDL IP) will be developed. TMDL IPs include a schedule of actions, costs, and monitoring. Plan development should start as soon as possible after EPA approval of the TMDL Study. Virginia state law requires the development of a TMDL IP. Local or state agencies as well as community watershed groups can take the lead in developing TMDL IPs. A TMDL IP Guidance Manual is available from DCR and DEQ.

What roles do different state agencies have in developing TMDLs?

TMDL development is a collaborative effort between several state agencies. DEQ is the lead agency in the TMDL process and develops the list of impaired waters, TMDLs for these waters, and IPs for certain types of TMDLs, for example where reductions are required from permitted sources. DEQ also administers the public participation component of the TMDL process, and formally submits the TMDLs to EPA and the State Water Control Board for approval. Virginia DEQ is also the lead for NPS pollution control activities and is responsible for the development of IPs for TMDLs where nonpoint sources are the dominant contributor. The Virginia Department of Mines, Minerals and Energy (DMME) administers the mineral extraction component of the TMDL process, awards and manages contractual services for TMDL development and special TMDL related studies. The Virginia Department of Health - Division of Shellfish Sanitation (VDH-DSS) is responsible for classifying shellfish growing waters and monitoring the waters for fecal coliform bacteria. VDH-DSS also conducts shoreline surveys to determine potential sources of contamination and collaborates during TMDL development.

How will the TMDLs be implemented?

DEQ intends for nonpoint source reductions recommended in TMDLs to be implemented through Best Management Practices (BMPs) and expect that implementation will occur in stages. The benefits of staged implementation are:

  • It helps to ensure the most cost effective practices are implemented first;
  • it allows for monitoring of water quality improvements as they are being achieved;
  • it provides a measure of quality control, given the uncertainties which exist in any model;
  • it provides a mechanism for developing public support; and
  • it allows for the evaluation of the adequacy of the TMDL in achieving the water quality standard.

Additional information:

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TMDL Implementation

What happens after the TMDL Study is complete?

The TMDL Study will be submitted to EPA which will have 30 days to review and approve the TMDL. Then a TMDL Implementation Plan (IP) will be developed. TMDL IPs include a schedule of actions, costs, and monitoring. Plan development should start as soon as possible after EPA approval of the TMDL Study. Virginia state law requires the development of an IP. Local or state agencies as well as community watershed groups can take the lead in developing TMDL IPs.

What funding will be available to help support the stakeholders' efforts in implementing the TMDLs?

DEQ fully realizes that Best Management Practices (BMPs) implementation is a costly undertaking. There are several sources of funding such as the Virginia Revolving Loan Fund, USDA's Conservation Reserve Enhancement Program (CREP) and Environmental Quality Incentive Program (EQIP), and Virginia's Agricultural Cost-Share Program. The state agencies involved in TMDL development (DEQ, DCR, DMME and VDH) projected an estimated cost to the Commonwealth of more than $500 million to implement TMDLs over the next 10-15 years. While it is not possible at this time to estimate specific dollar amounts that will be made available, it is not DEQ's intention to impose an unreasonable financial burden on the stakeholders.

How will TMDLs be implemented?

DEQ and DCR intend for nonpoint source TMDLs to be implemented through Best Management Practices (BMPs) and expect that implementation will occur in stages. The benefits of staged implementation are:

  • It helps to ensure the most cost effective practices are implemented first;
  • it allows for monitoring of water quality improvements as they are being achieved;
  • it provides a measure of quality control, given the uncertainties which exist in any model;
  • it provides a mechanism for developing public support; and
  • it allows for the evaluation of the adequacy of the TMDL in achieving the water quality standard.


What if it is not feasible to reach Water Quality Standards due to nature or uncontrollable factors?

DEQ's focus in this area is to ensure that the water quality goals we are trying to achieve are appropriate and worth the resources that will need to be spent to achieve them. In some streams, bacteria contributed by wildlife result in standards violations. In order to begin to address this issue, the Commonwealth has developed criteria to protect the secondary contact recreational uses. These new criteria will become effective pending EPA approval. In order for the new criteria to apply to a stream segment, the primary contact recreational use must be removed. To remove a designated use, the state must demonstrate that the use is not an existing use, that downstream uses are protected, and that the source of bacterial contamination is natural and uncontrollable by effluent limitations and BMPs, This and other information is collected through a special study called a Use Attainability Analysis (UAA). All site-specific criteria or designated use changes must be adopted as amendments to the water quality standards regulations. For additional information, go to DEQ Water Quality Standards.

Is there a list of Best Management Practices that might be employed in urban areas?

Each TMDL is specifically tailored to address the conditions and circumstances that pertain to that impaired water. Many urban area BMPs used in the past to reduce human bacteria loading from failing septic systems and leaking sewer lines include education on septic-pump-outs and a sanitary sewer inspection and management program. Also beneficial are controlling urban wash-off from parking lots and roads by implementing more restrictive ordinances to reduce bacteria loads from pets, improved garbage collection and control, and improved street cleaning. More detailed information can be found at North Carolina State University Water Quality Group.

More detailed information is also available in the TMDL IP Guidance Manual available from DEQ and DCR.

Is there a list of Best Management Practices that might be employed in agricultural areas?

Again, each TMDL is specifically tailored to address the conditions and circumstances that pertain to that impaired water. Many agricultural BMPs used successfully in the past to lower bacteria levels in streams include livestock exclusion from streams, reducing stormwater run-off from concentrated livestock areas by additional buffering in the riparian (near-stream) zone, and manure management practices. As in urban areas, addressing failing septic systems and straight pipes has been very effective. In general, riparian restoration activities have been shown to be very effective. More detailed information can be found at the following websites: http://www.water.ncsu.edu/watershedss/info/bmps_for_agnps.html and http://www.water.ncsu.edu/watershedss/descprob/strmbnks.html.

More detailed information is also available in the TMDL IP Guidance Manual available from DEQ and DCR.

What requirements may be added to MS4/VPDES permits as a result of TMDLs?

The regulatory basis linking NPDES permits and TMDLs is 40 CFR §122.44(d)(vii) of the Code of Federal Regulations. In November 2002, EPA published a guidance memorandum on the linkage between MS4 permits and TMDLs. For TMDLs, EPA requires that loading from stormwater covered by an MS4 permit must be expressed as a wasteload allocation (WLA). For MS4 permits, EPA expects that most TMDL WLAs will be expressed as BMPs and that numeric limits will be used only in rare circumstances. At this time, DEQ expects to apply the BMP option to address TMDLs in waters covered by MS4 permits. Revisions of the MS4/VPDES permits that apply to water bodies with TMDLs would then require implementation of BMPs to specifically address the TMDL pollutants of concern.

What requirements may be added to VPDES permits as a result of TMDLs?

Federal and state regulations require effluent limits to be 'consistent with the assumptions and requirements of any available waste load allocation prepared by the State and approved by EPA pursuant to' the federal TMDL regulations. For bacteria TMDLs, the WLA is calculated as the maximum permitted bacteria concentration multiplied by a maximum annual design flow. Functioning wastewater treatment plants typically do not contribute to bacteria pollution in streams. However, if a treatment plant is considering an expansion, that expansion could result in increased loading due to increased discharge and an increased WLA for the wastewater treatment plant. If the overall WLA in the TMDL does not have flexibility for future growth, the TMDL may have to be re-opened to re-calculate the overall WLA.

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The proactive approach to restoring waters impaired by bacteria

What is the Proactive Approach for Restoring Impaired Waterbodies?

The Proactive Approach aims to clean impaired water bodies through voluntary methods in order to avoid the costly and time-consuming process of developing Total Maximum Daily Loads, or TMDLs, and TMDL implementation plans (see TMDL Glossary for definitions).

What is the basis for the Proactive Approach in waters impaired by bacteria?

A number of bacteria TMDLs have been developed throughout Virginia and the nation. The findings for bacteria impairments have consistently demonstrated a commonality in the corrective actions that are needed to restore the stream so that it meets water quality standards. In rural agricultural areas, the elimination of cattle access to streams is the single most important corrective action, followed by the repair and/or replacement of failing septic systems. In rural residential areas, repair and/or replacement of failing septic systems and the elimination of straight pipes top the list of corrective actions. In urban areas, the maintenance of wastewater infrastructures and the control of pet waste are the top two items. Because of the consistent findings in the TMDL studies to date, the proactive approach proposes the implementation of corrective actions in advance of the TMDL. More detailed information on bacteria control strategies can be found at the following web site: http://www.water.ncsu.edu/watershedss/descprob/strmbnks.html/.

How does the Proactive Approach work?

The Proactive Approach utilizes the 'two-year look-back requirement' which mandates that an impaired water body would have to be meeting water quality standards for two years before qualifying for removal from the 303(d) list of impaired waters. Because in many cases, sources of bacteria pollution are obvious, and because bacteria pollution tends to respond rapidly to the implementation of Best Management Practices, or BMPs, waters impaired by bacteria are particularly suitable for the proactive approach. The three components of the proactive approach are as follows:

  • The proactive approach for a water body impaired by bacteria would be initiated by a search for in-or near stream sources of bacteria. This can be done by stream walks or with help from local experts from DEQ, VDH, DCR, USDA and other local, state and federal agencies.
  • Restoration efforts would then be targeted at these visible pollution sources for a limited number of years, e.g. one or two. Screening methods to identify hot spots might also be used.
  • At the end of that time period, DEQ's ambient monitoring over a two year period would allow an evaluation of water quality improvements.
If the water quality standard is being met, a TMDL would no longer be necessary and the water body would qualify for removal from the impaired waters list. If the water quality standard is not being met, more intensive monitoring and TMDL development would need to occur. As with the listing process and TMDL development, the U.S. Environmental Protection Agency is the approving authority for delisting a water body from the 303(d) list of impaired waters.







What are the limitations with the Proactive Approach?

Because almost all state resources at this time are focused on TMDL development, the biggest limitation is likely the lack of funding. This is because Virginia is required to submit a certain number of TMDLs every biennium and currently has no additional funds to support the proactive approach. However, numerous other funding sources are available that may be applied to this approach. The second limitation is organizational - in order for the approach to work, a watershed group or locality has to commit time and resources to focus and keep track of the restoration activities. On the other hand, this limitation also provides for the flexibility at the local level to address water quality problems in a targeted way.

How can the public participate in the Proactive Approach?

Because the proactive approach relies on voluntary implementation of corrective actions, the public's participation in the process is crucial. The public can participate in several ways:

  • Nominate potential candidates for the proactive approach to your local DEQ TMDL Coordinator (see address list below).
  • Find a sponsor for the proactive approach in your watershed and develop a Proactive Action Plan (see below).
  • Participate in stream walks and other data collection activities to help identify major sources of bacteria pollution.
  • Implement corrective actions on your property or help others to do so.

What are the steps toward a Proactive Approach?

First, identify a sponsor for the approach. This might be a locality or watershed group. Second, identify the visible bacteria sources in the watershed. Third, develop a cost estimate and reasonable timeline (no more than 3 years) for eliminating the sources. These three steps comprise the Proactive Action Plan. Lastly, contact your local DEQ office with the Proactive Action Plan and nominate the watershed for the proactive approach.

Contact information for DEQ TMDL Coordinators:

Contact can be found on the TMDL Program Contacts Page.

Further information on...

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Virginia Department of
Environmental Quality
P.O. Box 1105
Richmond, VA 23218
(804) 698-4000


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