Protecting Public Health and the Environment.

Wastewater in Idaho

Wastewater is spent or used water from households and businesses that contains enough harmful material to damage the water's quality. Every building with running water generates wastewater. 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 wastewater management and disposal protect public health and Idaho's surface and ground water resources. DEQ's Wastewater Program establishes standards for on-site wastewater systems (septic systems) and issues wastewater reuse permits limiting the amount of wastewater that may be land applied for irrigation.

Wastewater Collection and Treatment Systems

Any structure or facility that generates wastewater must dispose of it through a wastewater treatment and disposal system, either centralized or decentralized. Large-scale public sewer systems (municipal wastewater treatment plants) are centralized systems. Homes and other buildings that are not served by public sewer systems depend on decentralized on-site septic systems to treat and dispose of wastewater. Learn more.

Public Wastewater System Classification and Licensure

DEQ determines system classifications and ensures that all wastewater systems that generate, collect, treat, or dispose of 2,500 gallons or more of wastewater per day are supervised by an appropriately licensed responsible charge operator and licensed operating personnel. Learn more.

Wastewater Disposal Options

Once wastewater has been treated, it is disposed of by reintroducing it to the environment. Three methods for disposing of treated wastewater effluent are surface water discharge, subsurface discharge, and land application for beneficial use. Learn more.

On-Site Wastewater Systems (Septic Systems)

On-site systems use a septic tank and underground (subsurface) drainfield to treat wastewater on site. Septic systems dispose of household sewage, or wastewater, generated from toilet use, bathing, laundry, and kitchen and cleaning activities. On-site systems are the most common wastewater treatment system used in rural areas: 36% of Idaho's homes, or about 210,000 residences, use on-site septic systems to treat sewage. A properly designed, located, constructed, and maintained septic system is imperative to protecting human health and the environment. Learn more.

National Pollutant Discharge Elimination System

Industrial, municipal, and other point sources of pollution that discharge wastewater directly to surface waters are required to obtain National Pollutant Discharge Elimination System (NPDES) permits. NPDES permits limit the amount of pollution that point sources may discharge into surface waters. NPDES permits protect water quality and public health. In Idaho, the NPDES permit program is administered by the US Environmental Protection Agency (EPA), which means EPA is responsible for issuing and enforcing all of Idaho's NPDES permits. Learn more.

Lagoon Seepage Testing

Wastewater lagoons are designed to hold wastewater and are required to be seepage tested periodically. To understand how much liquid is seeping from a lagoon, a seepage test can be performed. Learn more.

Aquaculture in Idaho

Aquaculture cultivates freshwater fish, such as salmon and trout, under controlled conditions for commercial, conservation, and recreational uses. Idaho's aquaculture industry ranks as the third largest food-animal industry in the state and is the nation's largest commercial producer of Rainbow Trout. Aquaculture waste can have a negative impact on surface water and ground water. Good waste management and water stewardship ensure the quality of water in receiving streams. Learn more.

Concentrated Animal Feeding Operations

Concentrated animal feeding operations (CAFOs) are agricultural facilities that house and feed a large number of animals—typically cows, hogs, chickens, or turkeys—in a confined area for a length of time. Careful management of these facilities protects public health and the environment from runoff carrying animal waste into nearby sources of water and from animal waste leaching into ground water. Several agencies share responsibility for regulating CAFOs in Idaho. Learn more.

Stormwater in Idaho

Stormwater is rain or melting snow that does not immediately soak into the ground. Stormwater runs off of land and hard surfaces, such as streets, parking lots, and rooftops, and picks up pollutants, such as fertilizers, dirt, pesticides, and oil and grease. Eventually, stormwater soaks into the ground or discharges to surface water (usually through storm drains), bringing the pollutants with it. Federal, state, and local government agencies; business and industry; and individual land owners all share responsibility for stormwater management in Idaho. Learn more.

DEQ State Office - Water Quality Division

1410 N. Hilton
Boise, ID 83706
(208) 373-0502

Staff Contacts

Wastewater Engineering Manager
Larry Waters
(208) 373-0151

On-Site Wastewater Coordinator
Clark Weaver
(208) 373-0144