The Basics of TMDLs

Completion of the 1998 Court Decree and TMDL

Development Schedule

As of June 30, 2006, Kansas had completed its obligations to develop TMDLs in the twelve river basins of the state. 413 TMDLs addressing impairments that had appeared on the 1996 Section 303(d) list and the 1998, 2002 and 2004 lists were developed between January 1999 and June 2006. The Stipulation of Dismissal was filed on January 19, 2007 and so ordered by Judge Lungstrum on January 22, 2007.

The Kansas TMDL Program will now proceed on a five-year cycle through the river basins of the state, developing and revising TMDLs for selected impairments identified in the current Section 303(d) list. The selection of impairments to be addressed by TMDLs will be made jointly between KDHE and the Kansas Water Plan’s Basin Advisory Committee in each basin. The basins will be revisited and have TMDLs developed according to the following schedule:

2006: Kansas-Lower Republican & Lower Arkansas Basins were developed
2007: Upper Arkansas, Missouri & Marais des Cygnes Basins are to be developed
2008: Neosho, Verdigris & Walnut Basins are to be developed
2009: Smoky Hill-Saline, Solomon & Upper Republican Basins are to be developed
2010: Kansas-Lower Republican Basin is to be developed
2011: Upper and Lower Arkansas & Cimarron Basins are to be developed
2012: Missouri & Marais des Cygnes Basins are to be developed

Click here to view the Stipulation of Dismissal

What is a Total Maximum Daily Load?

Total Maximum Daily Loads (TMDLs) are quantitative objectives and strategies needed to achieve water quality standards. The water quality standards constitute the goals of water quality adequate to fully support designated uses of streams, lakes, and wetlands. The process of developing TMDLs determines:

  1. The pollutants causing water quality impairments
  2. The degree of deviation away from applicable water quality standards
  3. The levels of pollution reduction or pollutant loading needed to attain achievement of water quality standards
  4. Corrective actions, including load allocations, to be implemented among point and nonpoint sources in the watershed affecting the water quality limited water body
  5. The monitoring and evaluation strategies needed to assess the impact of corrective actions in achieving TMDLs and water quality standards
  6. Provisions for future revision of TMDLs based on those evaluations

The 1998 Court Decree and Schedules of Developing TMDLs

In 1995, the Kansas Natural Resource Council and the Sierra Club filed a complaint against the EPA, compelling it to enforce Section 303(d) of the Clean Water Act by establishing TMDLs. Kansas intervened in the litigation, since the state had lead responsibility for identifying the waters requiring TMDLs and establishing the TMDLs. A settlement was reached, and a consent decree approving the settlement was made on April 13, 1998. The court decree sets out a schedule for the state to submit TMDLs for water quality limited stream segments and lakes in each of the 12 major river basins in Kansas over an eight year period. Below is the anticipated standard and accelerated schedule of developing TMDLs by basin:

Year Decree Schedule Accelerated Schedule 303(d) List
June 30, 1999 Kansas-Lower Republican Kansas-Lower Republican 1998
June 30, 2000 Cimarron
Upper Arkansas
Lower Arkansas *
Upper Arkansas
June 30, 2001 Lower Arkansas * Marais des Cygnes
June 30, 2002 Marais des Cygnes
Neosho *
June 30, 2003 Neosho * Solomon
Upper Republican *
June 30, 2004 Walnut
Smoky Hill-Saline 2002
June 30, 2005 Smoky Hill-Saline Kansas-Lower Republican**
June 30, 2006 Solomon
Upper Republican
Lower Arkansas
Upper Arkansas**
Upper Republican

* Basins have carry over TMDLs needing to be done by June 30, 2006.
** Second round of developing priority TMDLs and revising.

Kansas is following the accelerated schedule. By following the accelerated schedule, the state has time to "mop-up" complex TMDLs generated by subsequent 303(d) lists. Subsequent, 303(d) lists are deemed Category 5 waters under current EPA Guidance. Category 5 lists waters impaired by pollutants and needing TMDLs. After completion of the 1998 Court Decree in 2006, Kansas will rotate through the basins on a five year schedule. TMDLs will be done on a priority basis within each basin. Below is the pending rotational basin TMDL development schedule.

Year Rotational Basin TMDL Development Schedule 303(d) List (Category 5 waters) Completion Date
2004 Kansas-Lower Republican
2004 303(d) List April 1, 2005
2005 Lower Arkansas
Upper Arkansas
Upper Republican
2004 303(d) List April 1, 2006
2006 Marais des Cygnes
2006 303(d) List April 1, 2007
2007 Neosho
2006 303(d) List April 1, 2008
2008 Smoky Hill-Saline
Upper Republican
2008 303(d) List April 1, 2009

It is anticipated that changes to water quality standards and future monitoring and assessment may remove and add waters to Category 5. All category 5 waters will have a TMDL or be re-categorized within 8 to 13 years of the initial Category 5 listing.

TMDLs established by Kansas may be done on a watershed basis and may use a pollutant-by-pollutant approach or a biomonitoring approach or both as appropriate. TMDL establishment means a draft TMDL has been completed, there has been public notice and comment on the TMDL, there has been consideration of the public comment, any necessary revisions to the TMDL have been made, and the TMDL has been submitted to EPA for approval. Should Kansas fail to comply with its obligations under the court decree, EPA must take appropriate action to establish the TMDLs in question within 180 days after the deadlines established in the court decree schedule.

Beginning January 31, 1999 and by January 31 of each year thereafter during the effective period of the court decree, EPA and Kansas shall provide the plaintiffs with a written report, jointly if possible, regarding the activities undertaken to comply with the court decree during the previous calendar year.

The court decree also provides for the remedy and scope of judicial review, dispute resolution, modification procedures for the schedule, recognized exceptions in compliance with the court decree, demonstration of good cause and termination of the decree and dismissal of the plaintiff claims.

The TMDL Process

Each TMDL Kansas submits to EPA will contain the following components:

A. Problem Identification: The pollutant causing the impairment and the designated uses that are impaired will be identified. The rationale for listing the stream segment, wetland, or lake on the Section 303(d) list will be described.

B. Current Situation and Desired Objective: The desired outcome of the TMDL process will be indicated, using the current situation as the baseline. Deviations from the water quality standards will be documented. The TMDL will state its objective in meeting the appropriate water quality standard by quantifying the degree of pollution reduction expected over time. Interim objectives will also be defined for midpoints in the implementation process.

Because numerous TMDLs will be written under the court decree schedule, a rapid method of discerning the current condition will be needed. In the case of TMDLs involving numeric criteria and monitoring data, Kansas will develop a load duration curve that will show the desired loadings over the range of flow conditions. An in depth explanation of the TMDL curve methodology is covered in the Data Analysis page.

For impairments involving narrative criteria or biomonitoring data, other indicators will be developed to define the TMDL objective. Examples of these indicators include biotic index values and trophic state indices. Current trends will be used to document the present conditions and define the quantitative outcome desired from establishing the TMDL.

Some water bodies were listed because the results of a simulation model indicated probable violation of water quality standards and impaired uses. The results of the modeling will be used, along with sensitivity analysis, to adequately define the conditions leading to impairment and the impact of corrective actions.

C. Source Assessment: Each pollutant source and its relative contribution to the water quality impairment will be determined. Based on TMDL curves, judgments can be made on the degree point and nonpoint sources contribution. The type and number of sources, their geographic location within the watershed, the magnitude of their potential pollutant loading, and the degree of influence on water quality will be identified.

For point sources, the assessment will include the type of wastewater and treatment, the volume of discharged effluent, the degree of compliance with existing permits, the expiration date of the permits, the potential for future growth, and the expected flow conditions which they are expected to protect. For nonpoint sources, information will be gathered on the land uses within the watershed, the underlying topographic and soil features, likely contributing areas producing runoff, the percent of impervious area producing stormwater discharges, stream-aquifer interactions, existing management practices in place, and types of water use present along the streams and lakes. The source assessment will also present any documented information on the background levels of pollutants emanating from natural sources or sources lying outside the effective area under TMDL development.

D. Load Allocation: The load allocation identifies the allowable loads for point, nonpoint, and background sources. The sources are assigned appropriate responsibility for pollutant reduction. A margin of safety is created to provide safeguards to the water body from the uncertainty inherent in the impacts of point and nonpoint sources.

E. Implementation: The implementation section describes the actions to be taken to manage point and nonpoint source contributions to pollutant loadings. Typically, a ten-year period of implementation actions will be anticipated after TMDL approval. In the case of point sources (municipal, industrial, and livestock), allocations of wasteloads will be made through renewed NPDES permits. The state will strive to place all NPDES permits within a watershed, and eventually throughout each basin, on the same schedule. For those point sources needing improvements, a compliance schedule will be developed. Use of the Kansas Water Pollution Control Revolving Loan Fund for upgrading wastewater facilities will continue to assign additional priority points to those scheduled projects discharging into a stream listed under Section 303(d) and subject to the conditions of a TMDL. Permits will reflect TMDL objectives by placing water quality-based limitations on effluent discharges.

For nonpoint sources, the focus will be placed on technical assistance, educational outreach, and directing financial resources toward placing best management practices in critical contributing areas of watersheds. The key strategy will be to reduce pollutant loadings from these areas to the maximum practicable extent. Most of these efforts will rely on voluntary, incentive-based approaches that are consistent with current practice of the Kansas Water Plan and federal programs.

Three mechanisms exist within state authority to address pollution sources, particularly those of a nonpoint nature.


  1. Critical Water Quality Management Areas. Watersheds may be designated as critical water quality management areas because of pollutant sources which may cause damage to resources of the state; public nuisance or health hazards; destruction of fishery habitats; excessive deposition of sediments on river bottoms, lakes, or reservoirs; additional risk to threatened or endangered fish or wildlife; or violation of water quality standards. KDHE evaluates all the pollutant sources and determines the technical and economic feasibility of simultaneous control of all pollutant sources. A proposed management plan is set forth with an implementation schedule for control of each source.
  2. Pesticide Management Area. The Kansas Department of Agriculture is empowered to develop pesticide management areas when notified by the EPA or KDHE that a pesticide poses a serious threat to the public health, safety, and welfare or to the natural resources of the state. The Department uses a technical advisory committee in establishing the boundaries and management plan for the proposed area.
  3. Source Water Protection Planning. Under the guise of the federal Safe Drinking Water Act, KDHE is to provide assistance and coordinate the development of state and local source water assessments to protect public water supplies. Such assessment planning delineates local public water supplies, inventories pollutant sources, analyzes the susceptibility of the pollutant risks, and informs the public on the present conditions, risks, and risk reduction plans associated with their water supplies. The program is coordinated with the State Wellhead Protection Program assessing the protection of ground water supplies.

F. Follow-up Monitoring: Implementation monitoring tracks the degree to which corrective or management practices have been put in place for point and nonpoint sources within the watershed. Nonpoint measures might include acres of land treatment implemented over time, increases in riparian area adjacent to streams, number of agricultural producers participating in cost-share programs, and participation in outreach education events focused upon nonpoint source reductions. Point source monitoring would include compliance monitoring relative to existing and future NPDES permits, episodes of combined sewer overflows, status of scheduled upgrades in treatment facilities, episodes of an emergency bypass through treatment works, maintenance schedules and upkeep for treatment facilities, and ongoing training for treatment works operators.

Resource monitoring assesses the improvement in water quality conditions in the impaired water body. Baselines need to be established to document current conditions. Trends over time will be analyzed. The ambient stream chemistry network will be generally maintained. Monitoring sites may be added, and the frequency of collection may increase. Biomonitoring will be used to determine the impact of activities on the biological community. The measures of success will be reductions in the frequency, magnitude, and duration of violations of the water quality standards over the next decade.

Occasionally, synoptic surveys may be conducted to further evaluate loadings in a watershed setting and confirm load contributions. Low flow intensive surveys will document impacts of effluent discharges on receiving waters. Storm water monitoring may be recommended to further evaluate the contributions of urbanized areas on nonpoint loadings. Some follow up modeling may also be conducted.

G. Feedback Mechanism: Over the ten-year implementation period, the causes of the impairment will become more clear, especially in nonpoint source situations. There will be interim objectives incorporated within the TMDL implementation schedule so that appropriate adjustments can be made at the midpoint of implementation. All implementation actions are available for review and adjustment within the time frame of trying to accomplish the objectives of the TMDLs. NPDES permits are renewed at least every five years. Best Management Practices are subject to availability of funding and administrative policies and will reflect revised directions provided by the Kansas Water Plan and its Annual Implementation Plan.


Data Analysis

Kansas TMDL Curve Methodology

  1. A flow duration curve for the gage site of interest is developed. This is done by generating a flow frequency table and plotting the points.
  2. Flow Duration Curve

  3. The flow curve is translated into a Load Duration (TMDL) Curve. To accomplish this, the flow value is multiplied by the water quality standard and by a conversion factor. The resulting points are graphed.
  4. Load Duration Curve

  5. A water quality sample is converted to a load by multiplying the water quality sample concentration by the average daily flow (on the day the sample was taken). Then, the load is plotted on the TMDL graph.
  6. Load Duration Curve with Samples Plotted

Points plotting above the curve (the purple line) represent deviations from the water quality standard and the permissible loading function. Those plotting below the curve represent compliance with standards and represent adequate quality support for the appropriate designated use. Similar analysis can be done for certain lakes, using cumulative frequency distributions of their volume or elevation.

The Information the Plots Provide

  1. Help to identify the issues surrounding the problem and differentiate between point and nonpoint source problems.
  2. Show seasonal water quality effects
  3. Address frequency of deviations (how many samples lie above the curve vs. those that plot below); magnitude (how far the deviations plot away from the curve); and duration (potentially how long the deviation is present) questions
  4. Compare water quality conditions between multiple watersheds
  5. Aid in establishing the level of implementation needed

Using the Load Duration Curve to Identify the Source(s) of Pollution

In this analysis, loads which plot above the curve in the flow regime defined as being exceeded 85-99 percent of the time are likely indicative of point source influences on the water quality. Point Source Issues are clearly identified as a discharge from a pipe, ditch, or other well-defined source. Those plotting above the curve over the range of 10-70 percent exceedence likely reflect nonpoint contributions. Nonpoint source issues are pollution associated with runoff or snowmelt from numerous, dispersed sources over an extended area. Some combination of the two source categories lies in the transition zone of 70-85 percent exceedence. Those plotting above the curve at exceedences less than 10 percent or more than 99 percent reflect extreme hydrologic conditions of flood or drought