TMDL Frequently Asked Questions

  1. What is a TMDL?
  2. What are water quality standards and beneficial uses?
  3. What is the 303(d) list?
  4. What is nonpoint source pollution?
  5. What are point sources?
  6. What about natural sources of pollution? Do we have to clean these up?
  7. What causes water pollution in Montana?
  8. What are the sources of water pollution?
  9. How do you calculate a TMDL?
  10. What is a load allocation?
  11. Does a TMDL mean more government rules and regulations?
  12. What happens if the TMDL plan doesn’t restore water quality?
  1. What is a watershed approach?
  2. How is the local community involved in watershed planning?
  3. Are funds available to help watershed groups restore water quality?
  4. Why is DEQ using the 1996 303(d) list?
  5. What is EPA’s role in TMDL development?
  6. What is the difference between a “pollutant” and “pollution”?
  7. How does a TMDL/water quality restoration plan benefit landowners?
  8. How can I get involved in the TMDL/water quality restoration planning process?
  9. Where can I find more information?

 

1. What is a TMDL?

A Total Maximum Daily Load is the total amount of a pollutant that a water body may receive from all sources without exceeding water quality standards. A TMDL can also be defined as a reduction in pollutant loading that results in meeting water quality standards.

The TMDL concept was created by the 1972 Federal Clean Water Act. Montana’s approach is to include TMDLs as one component of a comprehensive water quality restoration plan.

Click here for an informational brochure (PDF 577K)

2. What are water quality standards and beneficial uses?

The Montana Board of Environmental Review, a citizen panel appointed by the governor, establishes water quality standards and designates beneficial uses of rivers, lakes and streams. Beneficial uses can be grouped into three broad categories:

  • Recreation includes swimming, boating and other water activities that involve physical contact with water.
  • Aquatic life includes the plants and animals that are the basis of a healthy aquatic ecosystem. Fish, of course, are aquatic life. However, fisheries are listed as a separate beneficial use due to their recreational and economic importance. Waterfowl and “fur bearers” are also considered beneficial uses.
  • Water supply encompasses domestic, municipal, industrial and agricultural uses.
Every water body has designated beneficial uses based on the Montana Water Classification System.

Montana's Water Classification System

A - Very high quality waters suitable for all beneficial uses
including public water supply.

B - Suitable for multiple uses including domestic water supply after
conventional treatment. `The B classification is divided into cold water
fisheries, commonly mountain or foothill streams and lakes that support
trout and associated fish (B-1 and B-2); and eastern prairie waters that
typically support sauger, catfish and other warm water fish species
(B-3). Most Montana water bodies are in the B classification.

C - Suitable for all uses except drinking water; as with the B classification,
C-1 and C-2 streams should support cold water fisheries and C-3 warm
water fish.

I - Water bodies that were impaired for drinking water, fisheries and
recreation in 1955. There are three I streams segments in Montana. It
is the long-term goal of the state to restore beneficial uses to all impaired surface waters.

Water quality standards support and protect beneficial uses. Some water quality standards are numeric. For example: 10 milligrams nitrate per liter of water. Other water quality standards are narrative: "No increases are allowed above naturally occurring concentrations of sediment, settle able solids, oils or floating solids which will or are likely to create a nuisance or render the waters detrimental, or injurious to public health, recreation, safety, welfare, livestock, wild animals, birds, fish or other wildlife."

There are four categories of beneficial use support:

  1. Fully supporting: Water quality is at its natural or best practical condition.
  2. Threatened: Currently supports all beneficial uses but there is a downward trend in water quality or new industry or population growth may pose a threat to water quality.
  3. Partially supporting: A broad designation that extends from “slightly impaired” to “barely supporting” beneficial uses.
  4. Nonsupporting: Fails to support designated beneficial uses due to acute toxicity, human health risks, or biological and physical indications of severe degradation.

HEALTHY

UNHEALTHY

Unimpaired

Impaired
Fully Supporting Threatened Partial Support Non Support
Physical, Biological, Chemical Indicators INDICATORS Physical, Biological, Chemical Indicators Physical, Biological, Chemical Indicators
Physical Biological Chemical

A river, lake or stream may fully support some beneficial uses while being impaired for other uses. For example, the water quality of a stream may be adequate for agriculture or industrial use but not high enough for drinking water supply.

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3. What is the 303(d) list?

Every two years the Department of Environmental Quality compiles a list of water bodies that fail to meet water quality standards. This document is known as the 303(d) list after the section of the Federal Clean Water Act that requires states to report impaired waters. The 303(d) list identifies the probable causes of impairment as well as the suspected sources of the pollutant. DEQ is required to develop TMDLs for all water bodies on the 303(d) list.

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4. What is nonpoint source pollution?

Nonpoint sources are generally land extensive activities that do not require discharge permits. Nonpoint sources include many agriculture and forestry activities, as well as small construction projects and unregulated storm water discharges.

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5. What are point sources?

Point sources are discharges from an identifiable outfall such as a pipe or ditch. Point source discharges are regulated by permits issued by the Department of Environmental Quality. Examples of point sources include municipal sewage treatment plants, factories, some storm sewers and large livestock feedlots.

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6. What about natural sources of pollution? Do we have to clean these up?

Some Montana waters have naturally high levels of salinity, turbidity or other parameters that limit the uses they can support. A TMDL/water quality restoration plan does not attempt to improve a water body beyond its natural or best practicable condition.

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7. What causes water pollution in Montana?

Table 1 lists the major causes of water pollution in Montana. The second column is the number of water bodies impaired by each use. This information is from the 2000 303(d) list.

TABLE 1:

Some Causes of Water Quality Impairments
Cause of Water Quality Impairment Number of Water Bodies
Algal growth/ chlorophyll a 16
Arsenic 36
Bank erosion 72
Cadmium 39
Channel incisement 20
Copper 56
Dewatering 93
Fish habitat degradation 85
Flow alteration 181
Lead 62
Mercury 47
Metals 185
Nitrates 16
Noxious Aquatic Plants 6
Nutrients 102
Organic Enrichment/low DO 6
Other Habitat Alterations 279
Pathogens 14
PCBs 6
pH 12
Phosphorous 14
Riparian Degradation 102
Salinity/TDS/Chlorides 8
Salinity/TDS/Sulfates 12
Selenium 12
Siltation 155
Suspended Solids 19
Thermal modifications 45
Turbidity 11
Zinc 40
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8. What are the sources of water pollution?

Ninety percent of stream pollution and eighty percent of lake impairments come from nonpoint sources. Montana is a large rural state with a small population. Farms and ranches cover two-thirds of the state and cows out-number people almost three-to-one. Therefore it is not astounding that agriculture is one of the leading sources of nonpoint pollution. Other significant sources include resource extraction (mining), streambank and streambed modifications and construction. Our largest lakes are impacted by atmospheric deposition of pollutants.

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9. How do you calculate a TMDL?

A TMDL = point source waste load allocations + nonpoint source load allocations + natural sources + growth factor + a margin of safety (to compensate for uncertainties about the link between pollutant loads and impairments).

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10. What is a load allocation?

A load allocation is the part of a TMDL/water quality restoration plan that assigns reductions to meet identified targets. The load may be divided by land use (rangeland, cropland), or activity (construction, timber harvest) or assigned to subwatersheds or tributaries. In a perfect world, the amount of load reduction would be proportionate to a source’s contribution. However, this is not always feasible. The relative cost of achieving reduction targets may be greater for some contributors than others. State law requires DEQ to consider “the environmental, social and economic costs and benefits” of implementing a TMDL/water quality restoration plan.

TMDL pie chart, pieces of the pie include Factories, Ag, Forestry, Municipal WTP, Urban Run-off

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11. Does a TMDL mean more government rules and regulations?

Montana relies on a nonregulatory approach to address nonpoint source pollution. Land managers and water users are encouraged to adopt a “voluntary program of reasonable land, soil and water conservation practices that result in meeting water quality standards.” Under state law, DEQ cannot “divest, impair or diminish” any recognized water right in the implementation of a TMDL.

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12. What happens if the TMDL plan doesn’t restore water quality?

If monitoring indicates that water quality standards are not being achieved five years after a plan is approved, DEQ conducts a formal evaluation to determine if:
  1. The implementation of new and improved management practices are necessary;
  2. Water quality is improving but more time is needed to comply with water quality standards; or
  3. Revisions to the plan are necessary to meet water quality standards.
Although it is an objective of the state’s Nonpoint Source Management Plan to implement water quality restoration plans within five years of EPA approval, DEQ recognizes that some water quality problems will not be resolved quickly or inexpensively. The mandated five-year evaluation will identify areas that require additional resources and greater efforts to restore beneficial uses.

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13. What is a watershed approach?

A watershed is a geographic area drained by a river or stream. A watershed is as large as the Mississippi River Basin or as small as the Roe River watershed, a 53-foot long river near Great Falls. A watershed approach is based on the premise that water quality restoration and protection are best addressed through integrated efforts within a defined geographic area.

DEQ has divided the state into 91 watershed planning areas to facilitate development of TMDL/water quality restoration plans. The department has developed a schedule for completing restoration plans for all areas by May 2007 (see figure 1).

FIGURE 1. TMDL Planning Areas and Schedule

TMDL Planning Areas/Schedule Map

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14. How is the local community involved in watershed planning?

State law directs DEQ to consult with watershed groups and conservation districts during all phases of water quality restoration planning. DEQ is directed to request the participation of farmers, ranchers, environmentalists and recreationists as well as representatives of the Department of Natural Resources and Conservation, the U.S. Forest Service, Bureau of Land Management, municipalities and the forest, tourism and mining industries. However, each watershed group reflects local land and water uses in the community. Conservation districts often take the lead in organizing watershed based efforts and serve as fiscal and administrative agents for watershed groups. Watershed groups and conservation districts determine their own level of participation in the planning process. Close collaboration with DEQ is essential to develop a scientifically defensible water quality plan in a timely manner. (FIGURE 1. TMDL Planning Areas and Schedule)

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15. Are funds available to help watershed groups restore water quality?

DEQ administers Section 319 grants. This program was created by the Federal Clean Water Act to help states address nonpoint source pollution. The money can be used for watershed planning, monitoring, restoration and information/education activities. For more information see: http://deq.mt.gov/wqinfo/nonpoint/Grants/319Grants.asp

Other agencies also have programs to assist in watershed restoration. For example, Fish, Wildlife and Parks’ Future Fisheries program and USDA’s Environmental Quality Incentives Program (EQIP).

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16. Why is DEQ using the 1996 303(d) list?

In1997 the legislature required DEQ to use “sufficient, credible data” in making beneficial use determinations. As a result of the new definition of sufficient, credible data, 486 water bodies were removed from the 2000 303(d) list pending reassessment. However, a federal judicial order requires EPA and DEQ to complete “all necessary TMDLs” for all water bodies on the 1996 303(d) list by May 5, 2007.

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17. What is EPA’s role in TMDL development?

EPA has the statutory responsibility to approve TMDLs for pollutants as defined by the Federal Clean Water Act. DEQ and EPA have signed a cooperative agreement describing each agency’s role and responsibility in TMDL development in Montana. EPA will take the lead in developing TMDL/water quality restoration plans for several watershed planning areas including the Powder/Tongue, Lake Helena, Dearborn, Yaak, Smith and others. EPA is also providing technical and financial assistance to DEQ throughout the state.

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18. What is the difference between a “pollutant” and “pollution”?

A pollutant, as defined by the Clean Water Act, is a contaminant discharged to water. Pollutants include sediment, metals, chemicals, pathogens and other wastes. Beneficial uses are also impaired by flow alteration, habitat degradation, bank erosion, channel incisement, dewatering and water level fluctuations. These impairments are defined as “pollution” by EPA. While EPA only reviews pollutant TMDLs, many local watershed groups have developed water quality restoration plans that address other issues. Section 319 funds can be used to address pollution impairments. Often a “pollution” impairment is related to a “pollutant.” For example, bank erosion is a source of sedimentation.

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19. How does a TMDL/water quality restoration plan benefit landowners?

A TMDL plan reduces much of the uncertainty and ambiguity of water quality regulations. A TMDL plan lets farmers, ranchers, contractors, foresters and other land managers and water users know how much sediment, pathogen or nutrient discharge is too much. A landowner who implements the best management practices identified in the restoration strategy of a TMDL plan can be confident that he will be in compliance with state and federal clean water laws.

When implemented, a TMDL/water quality restoration plan makes the local community a better place to live. Swimming and other water-based recreation is safer, fishing is better and the water is cleaner. Landowners can take pride in addressing and solving resource issues at the local watershed level.

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20. How can I get involved in the TMDL/water quality restoration planning process?

Contact your local conservation district and ask if there is a watershed group working in your area. You can also find the names and addresses of active watershed groups on the Montana Water website http://water.montana.edu/watersheds/groups/

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21. Where can I find more information?

Visit DEQ’s TMDL website  http://www.deq.mt.gov/wqinfo/TMDL/index.asp or contact DEQ’s water quality/TMDL staff

FAQs 12/3/2002