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Idaho Nonpoint Source Pollution (14-ID-a)

The Idaho Department of Environmental Quality (IDEQ) developed Idaho's initial nonpoint source program in 1989 and has ambitiously pursued its implementation, dedicating personnel and monetary resources to the advancement of nonpoint source water pollution control activities. (See Idaho DEQ Nonpoint Source Pollution Webpage).

Unlike pollution that is discharged directly from a pipe into surface waters, nonpoint source (NPS) pollution comes from many diffuse sources. It generally does not have a single point of origin. NPS pollutants can be natural, such as sediment, or human-made, such as chemicals and toxics. They are generally created in or on the land and carried off by stormwater runoff when it rains or the snowpack melts. As the runoff moves, it picks up and carries away the pollutants, finally depositing them into nearby surface waters, including streams, rivers, and lakes. Nonpoint pollutants may eventually leach into groundwater. This hazard is especially important because more than 90 percent of Idaho's drinking water comes from groundwater.

Participation in Idaho's nonpoint source program is optional and does not result in nor require a separate permit. A developer may wish to participate in the program in order to obtain a Section 319 Grant under the Clean Water Act.

Nonpoint Source Pollution Process

14-ID-a.1 – Will the Project Affect Impaired Waters

The federal Clean Water Act requires states and tribes to restore and maintain the chemical, physical, and biological integrity of the nation's waters and to adopt water quality standards necessary to protect fish, shellfish, and wildlife while providing for recreation in and on the waters whenever possible.

Water quality standards have been established by the Idaho legislature and approved by the United States Environmental Protection Agency (EPA). These standards are designed to protect, restore, and preserve water quality in areas designated for specific uses such as cold, cool, or warm water fisheries; agricultural water supply; recreation; wildlife habitat; and aesthetics. Uses have been designated for most, but not all, water bodies within Idaho.

Section 303(d) of the Clean Water Act establishes requirements for states and tribes to identify and prioritize water bodies that do not meet water quality standards. Currently, IDEQ is required to conduct a comprehensive analysis of Idaho's water bodies every two years to determine if they meet water quality standards. This analysis is published and submitted to the EPA in a document called an "Integrated Report." Idaho must develop a water quality improvement plan, called a total maximum daily load (TMDL), for those water bodies not found to be meeting water quality standards. A subbasin assessment (SBA) is the first step toward developing a TMDL.

About 36% of Idahos streams were identified in the 2008 Integrated Report as not meeting water quality standards, and TMDLs must be developed for each of these. Idaho and the EPA have a legal, court-ordered responsibility to ensure that these impaired waters are dealt with in a timely manner (see Idaho TMDL Settlement Agreement).

In Idaho, TMDLs are assessed on a subbasin level, which means water bodies and pollutants within a hydrologic subbasin are generally addressed in a single document. A subbasin is based on a cataloging unit of the U.S. Geological Survey (USGS) (a subbasin is the same as a USGS fourth field hydrologic unit, or HUC). There are 84 subbasins (HUCs) in Idaho.

14-ID-a.2 – Consult with IDEQ to Determine Total Maximum Daily Load (TMDL) Requirements and TMDL Implementation Plan Provisions

Section 303(d) of the federal Clean Water Act requires states to develop water quality improvement plans, called "total maximum daily loads" or TMDLs, for water bodies that are not meeting their beneficial uses. The goal of a TMDL is to set limits on pollutant levels to correct water quality impairments and achieve beneficial uses of water bodies through attainment of water quality standards. The United States Environmental Protection Agency (EPA) must approve each TMDL. Once the EPA has approved a TMDL, an implementation plan is written, typically within 18 months.

An implementation plan is a document, guided by an approved TMDL, that provides details of the actions needed to achieve load reductions, outlines a schedule of those actions, and specifies monitoring needed to document action and progress toward meeting water quality standards. An implementation plan provides a framework for local stakeholders to use to reach the goals established in the TMDL.

An implementation plan generally includes the following elements:

  • A list of actions needed to reduce pollutant concentrations
  • A timeline for implementing the plan
  • Reasonable assurances that implementation will occur
  • A list of who will be responsible for undertaking planned actions
  • An explanation of how progress on actions will be tracked
  • A monitoring or modeling plan with milestones for measuring progress
  • A description of how data will be evaluated and used to recommend revisions to the TMDL
  • A schedule of dates by which water quality standards are expected to be met, including interim goals or milestones as deemed appropriate

Plans are developed by a variety of stakeholders including government agencies, local citizens, and the watershed advisory group (WAG) for the area. Designated government agencies and the WAG are generally the driving force behind the plan and are responsible for identifying appropriate implementation measures. DEQ serves as the repository for implementation plans and often coordinates, or assists in, developing the plan, writing the document, and prioritizing projects for implementation. However, it is often other agencies (such as the Idaho Department of Lands or the Soil Conservation Commission) that actually write the plan.

Once an implementation plan is written and has been reviewed by the WAG, the designated agencies and others begin to implement the actions outlined in the plan. However, pollution control measures are often well underway before the plan is completed. Some pollutant control measures are in place before the TMDL is written and others are implemented during the TMDL/implementation plan writing process. Controlling pollutants is a long, on-going process, not something that occurs at just one point in time or just because an implementation plan has been written.

IDEQ, the WAGs, and the designated agencies regularly monitor progress toward meeting TMDL goals and revise the plan accordingly. Implementation plans are designed to be living documents that regularly change based upon new knowledge or technologies and the results of continued monitoring that show progress, or the lack thereof, toward meeting goals.

The following agencies are “designated agencies” according to I.C. 39-3602 - Water Quality--Definitions, responsible for implementing the plan:

  • Idaho Department of Lands (timber harvest, oil and gas exploration and development, and mining issues)
  • Soil Conservation Commission (grazing and agriculture issues)
  • Idaho Department of Transportation (public road issues)
  • Idaho Department of Agriculture (aquaculture issues)
  • IDEQ (all other issues)

The United States Forest Service and the Bureau of Land Management, through governmental memoranda of understanding, also serve as designated agencies on the federal lands they manage. Ultimately, however, it is all the on the ground land managers, landowners, and citizens who are responsible for implementation, and who reap the rewards of achieving the plan's goals.

14-ID-a.1 – Does Developer Wish to Implement Additional Nonpoint Source Pollution Controls

Nonpoint source pollution controls are largely voluntary because they are not regulated under NPDES permits for point source discharges and not permitted by any state agency. However, there are grant and funding programs available for developers who wish to add additional protections for nonpoint source pollution at their sites.

14-ID-a.1 – Determine if Section 310 Subgrants are Available for Project (Awarded Annually)

Section 319 of the Clean Water Act established a grant program under which states, territories, and tribes may receive funds to support a wide variety of nonpoint source pollution management activities, including technical assistance, financial assistance, education, training, technology transfer, demonstration projects, and monitoring to assess the success of specific nonpoint source implementation projects. DEQ is the state agency responsible for administering the §319 subgrants program in Idaho. Grants are awarded annually on a competitive basis.

To be eligible for §319 grants, a state must first develop and obtain EPA approval of an NPS pollution assessment report. The assessment report identifies waters impacted or threatened by NPS pollution and describes the categories of NPS pollution, such as agriculture, urban runoff, or forestry, that are causing water quality problems. In addition, the state must develop and obtain EPA approval of an NPS pollution management program. This program becomes the framework for controlling NPS pollution described in the assessment report.

A successful grant must focus primarily on improving the water quality of lakes, streams, rivers, and aquifers. Funds may be used to address a variety of NPS management and prevention activities, including:

  • Agriculture (except those activities covered by a draft or final NPDES permit).
  • Urban Stormwater Runoff (except instances covered by a draft or final NPDES permit).
  • Transportation (except instances covered by a draft or final NPDES permit).
  • Silvicultural or Forestry-related Activities.
  • Mining (except those activities covered by a draft or final NPDES permit).
  • Groundwater Activities (to the extent identified by the state’s NPS management program, including source water protection efforts that involve regional collaboration or have statewide application).
  • Hydrologic and Habitat Modification and Related Activities (including wetlands reconstruction).

Idaho passes through the large majority of its §319 funds to the local level for on-the-ground TMDL implementation projects. Remaining funds are used to support administration and implementation of the NPS Management Program and regional office activities.

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Contact Information

Edit Idaho Department of Environmental Quality
Nonpoint Source Pollution Contact 208.373.0464 daveabbazabbapisarski@deqabbazabbaidahoabbazabbagov Visit Website