Department of
Environmental Quality

Water Quality

DEQ's Water Quality Division is responsible for assuring that the state's surface, ground, and drinking water resources meet state water quality standards. Among the Division's major duties are to:

• Adopt water quality standards to protect public health and welfare, enhance the quality of water, and meet the requirements of the federal Clean Water Act.
• Certify that projects that require federal permits or licenses, such as a license to operate a hydroelectric dam, will not cause a violation of state water quality standards.
• Monitor and assess the levels of pollutants in surface waters such as rivers and streams and report on surface water quality.
• Work with communities, industry, and citizen groups to develop and implement water quality improvement plans when water quality fails to meet state water quality standards and provide grants to support a variety of water quality improvement activities.
• Work with public health districts to protect the quality of public drinking water by assisting public drinking water systems to comply with state requirements, conducting sampling surveys and on-site visits, reviewing water system plans and specifications, and providing training and outreach to water systems. DEQ also assesses potential contaminant threats to Idaho's drinking water sources.
• Protect ground water from pollution, clean up degraded ground water to support beneficial uses where feasible, and monitor and assess ground water quality.
• Provide guidance for managing stormwater discharges generated by runoff.
• Establish standards for treating and disposing of wastewater managed by on-site wastewater systems (septic systems) that are not served by public sewer systems.
• Issue wastewater reuse permits to protect surface and ground water by establishing limits on the amount of wastewater that facilities and industries may use for irrigation or other purposes, provide technical assistance, conduct inspections, enforce permits when necessary.

Planning

DEQ is required by section 303(e) of the Clean Water Act to develop a Continuing Planning Process (CPP) that describes the ongoing processes and planning requirements of the state’s Water Quality Management Plan (WQMP). The CPP provides a broad overview of how the state’s water resources are managed. Learn more.

Drinking Water

DEQ has been delegated authority by the federal government to administer Idaho's Drinking Water Program under the provisions of the federal Safe Drinking Water Act and the Idaho Rules for Public Drinking Water Systems. The program works with public health districts to protect the quality of public drinking water by assisting public drinking water systems to comply with state requirements, conducting sampling surveys and on-site visits, reviewing water system plans and specifications, and providing training and outreach to water systems. The links below provide access to information directed to public drinking water systems and Idahoans who rely on these systems for safe drinking water. Learn more.

Grants and Loans

Financial assistance is available through DEQ to assist communities in building and upgrading their public drinking water and wastewater systems. Grants are also provided to protect sources of public drinking water and to improve the water quality of lakes, streams, rivers, and aquifers. Learn more.

• Public Water System Planning Grants
• Public Water System Construction Loans
• Public Wastewater System Planning Grants
• Public Wastewater System Construction Loans
• Drinking Water and Wastewater Grants and Loans Letter of Interest Forms for FY 18
• Green Project Reserve
• Source Water Protection Grants
• Nonpoint Source Management §319 Subgrants
• Environmental Review

Ground Water

Ground water is a key resource supporting many aspects of Idaho's way of life. It replenishes our streams and rivers and provides fresh water for irrigation, industry, and communities. In addition, ground water supplies 95% of the state's drinking water. As Idaho's population grows, so does the need for clean, usable ground water. Learn more.

Idaho Pollutant Discharge Elimination System

In 2014, the Idaho Legislature revised Idaho Code to direct DEQ to seek EPA authorization for a state-operated pollutant discharge elimination system permitting program. The current program is operated by EPA and called the National Pollutant Discharge Elimination System (NPDES) program. The state program will be called the Idaho Pollutant Discharge Elimination System (IPDES) program.

• Idaho Pollutant Discharge Elimination System Program: Guidance Development
• Idaho Pollutant Discharge Elimination System: Program Application

Source Water

Source water is the untreated ground water (aquifers and springs) and surface waters (rivers, streams, and lakes) used to supply drinking water for private, domestic wells and public water systems. Ground water and surface water used for drinking water supplies are often vulnerable to contamination from land use practices and potential contaminant sources within the vicinity of drinking water wells and intakes. Learn more.

• Source Water Protection in Idaho
• Source Water Assessments in Idaho
• Source Water Protection Activity Guide

Surface Water

Surface waters consist of rivers, streams, lakes and reservoirs, and wetlands in Idaho. These waters not only provide great natural beauty, they supply the water necessary for drinking, recreation, industry, agriculture, and aquatic life as well. DEQ water quality protection efforts are designed to ensure surface waters meet their designated beneficial uses and Idaho water quality standards. Learn more.

• Water Quality Standards
• Beneficial Uses
• Antidegradation
• Water Quality Criteria
• Mercury in Surface Water
• Temperature
• Monitoring and Assessment
• Nonpoint Source Pollution
• Total Maximum Daily Loads (TMDLs): Water Quality Improvement Plans
• Water Quality Pollutant Trading
• Water Quality Studies and Reports
• Blue-Green Algae and Harmful Algal Blooms

Wastewater

Wastewater is spent or used water from households and businesses. Wastewater may contain contaminants such as oil, dirt, human waste, and chemicals. Untreated wastewater can cause serious harm to the environment and threaten human health. Proper management and disposal of wastewater is essential to protect public health and Idaho's surface and ground water resources. Learn more.

• Wastewater Collection and Treatment Systems
• Public Wastewater System Classification and Operator Licensure in Idaho
• Wastewater Disposal Options
• On-Site Wastewater Systems (Septic Systems)
• Sludge & Biosolids
• Wastewater Lagoon Seepage Testing
• Aquaculture in Idaho
• Concentrated Animal Feeding Operations
• Stormwater in Idaho