What is a Total Maximum Daily Load (TMDL)?
A Total Maximum Daily Load, or TMDL, is the maximum amount of a pollutant a waterbody can receive and still meet its appropriate water quality criteria or goal. The Nebraska Department of Environment and Energy is continuing to develop TMDLs in waterbodies across the state, giving priority attention to those waterbodies that have been listed as Category 5 - or impaired by one or more pollutants - in the state’s bi-annual Surface Water Quality Integrated Report.
What factors must be considered when determining a TMDL?
When determining this maximum amount of a pollutant that a waterbody can receive (also known as “loading capacity”), NDEE considers the following contributions:
- Point sources – Direct discharges into the waterbody, including such sources as wastewater treatment facilities and industrial facilities;
- Nonpoint sources – Diffuse sources of runoff, such as agriculture, urban and construction site runoff;
- Natural sources – Such as wildlife and soils;
- Other considerations – When determining the maximum pollutant amount, a margin of safety and seasonal variations are also factored into the analysis.
How do water quality management plans fit in to the TMDL process?
There are two major portions of the TMDL process. First is the identification of impaired waters, through the Section 303 (d) list of impaired waters, which is found in the agency’s Integrated Report. The second step is the development and implementation of water quality management plans to remediate or protect the listed waters.
The development of a TMDL includes:
- Determining the “loading capacity,” or maximum pollutant amount, of the identified waterbody for the pollutant of concern;
- Determining the existing load in the identified waterbody for the pollutant of concern. (In addition to identifying the existing load, allowances for future sources of pollutants can also be considered.)
- Determining the reduction necessary in the pollutant of concern to remediate or protect the identified waterbody;
- Developing a plan that allows the achievement of the necessary reductions in the pollutant of concern.
If a TMDL is required for a waterbody, contributing sources to the pollutant loads may be required to make reductions.
When is a TMDL required?
TMDLs are required for all waterbodies that have been included in Category 5 of Nebraska’s Surface Water Quality Integrated Report. Category 5 is identified as: “Waterbodies where one or more beneficial uses are determined to be impaired by one or more pollutants and all of the TMDLs have not been developed. Category 5 waters constitute the Section 303(d) list subject to EPA approval/disapproval.”
What is the “Integrated Report”?
The Integrated Report is a comprehensive summary of the water quality of Nebraska’s surface water quality resources. The report provides the general public information on the status of the State’s waters and allows for future water quality management planning (future monitoring, TMDL development, best management practice implementation).
Is the Integrated Report new?
In the past, the NDEE prepared two documents as required by the Clean Water Act.
- The Section 303(d) list of impaired waters. The Section 303(d) list identifies and establishes a priority ranking for all waterbodies in which technology-based effluent limitations are not stringent enough to attain and maintain applicable water quality standards. This information is used to establish total maximum daily loads (TMDLs) for the pollutants causing impairment in those waterbodies.
- The Section 305(b) Report. This portion of the Integrated Report describes the status and trends of existing water quality for all waters of the state and provides information regarding: the extent to which designated uses are supported; pollution problems and sources; and the effectiveness of the water pollution control programs.
In 2003, EPA issued guidance which combines these two reports into one “Integrated Report.” EPA’s goal for this report is to provide the general public with a comprehensive summary of state and national water quality.
What data is used to develop Nebraska’s Integrated Report?
The NDEE utilizes all available data that meets the established data quality requirements for use in the Section 303(d) listing process. The data quality requirements are described in the Methodologies for Waterbody Assessment and Development of the 2008 Integrated Report for Nebraska. The NDEE will consider any data provided by other agencies, organizations or the public.
Where can I get a copy of Nebraska’s Surface Water Quality Integrated Report?
The Nebraska Surface Water Quality Integrated Reports are available on this website or can be obtained by contacting NDEE. View the Impaired Waters and Total Maximum Daily Loads (TMDL) webpage.
How will TMDLs be developed?
There are many ways to develop a TMDL. A TMDL can be developed using simple calculations or complex water quality models. Its development is dependent upon the waterbody involved, properties of its watershed, pollutants of concern, local stakeholder involvement, as well as other considerations. The method used depends on the seriousness of the water quality problem, data available and the potential ramifications of the final outcome on the people and businesses of Nebraska. The goal of all TMDLs will include the minimum elements of a loading capacity, wasteload allocation, load allocations, margin of safety and consideration of seasonal variation.
What happens after the NDEE completes a TMDL?
After the TMDL is initially developed by the NDEE it will be made available to local stakeholders and the public for review and comment. Public availability announcements will be mailed to interested parties and posted on the NDEE’s website. Those that are currently open for public comment will be listed in the TMDL category in the Public Notice portion of the website. The NDEE will allow a minimum of 30 days for the receipt of comments. Once the comment period closes, all received comments will be reviewed and, if appropriate, utilized to prepare a final TMDL. The final TMDL will then be submitted to the U.S. Environmental Protection Agency’s (EPA) Region 7 Office, for their approval.
What is EPA’s role after the TMDL has been submitted?
Once a final TMDL is submitted to EPA, EPA has 30 days to approve or disapprove the TMDL. If EPA disapproves the submitted TMDL, then, by federal regulations, EPA must revise or develop a new TMDL within 30 days. If EPA approves the submitted TMDL, the state then proceeds to implement the identified water quality management measures needed in order for the waterbody to attain the applicable water quality criteria or goal.
How can the public get involved in the TMDL process?
- Keep informed as to the water quality status of the local watershed.
- Review and comment on proposed TMDLs.
- Take part in a local community-based watershed management organization.
- Assist in TMDL implementation through voluntary best management practice application.
Is there information on the TMDL program available on the Internet?
There are several active web sites that contain information on the TMDL program, including state, federal and nonprofit organizations.
These sites include:
Who can I contact if I have questions regarding the Nebraska TMDL program?
If you have questions or need additional information, contact:
Planning Unit, Water Quality Division
Nebraska Department of Environment and Energy
* This webpage contains links to Non-NDEE websites, these links will open in a new tab or window