Department of
Environmental Quality

Aquaculture is the cultivation of fish under controlled conditions for commercial, conservation, and recreation purposes. 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. The aquaculture industry, including support industries such as veterinary services and feed production, employs approximately 800 people in Idaho.

The aquaculture facilities in Idaho include both cold water facilities that raise trout, steelhead, salmon, and sturgeon and warm water facilities that raise catfish, tilapia, and tropical fish. These facilities consist of either a set of ponds or earthen or concrete raceways, situated in series (each pond flows into the next pond) or in parallel (each pond flows separately to the treatment system or discharge point). Private and government-operated aquaculture facilities must all abide by the same rules and regulations.

There are approximately 115 permitted aquaculture facilities in Idaho, nearly 70% of which operate in the Magic Valley, discharging to the Snake River or its tributaries.

Aquaculture and the Environment

Aquaculture waste can have a negative impact on surface water and ground water. While fish have always been a natural part of Idaho's fauna, the unnaturally high concentrations of fish and fish wastes at aquaculture facilities can pose environmental problems.

Both solid and liquid pollutants are by-products of raising fish in large concentrations within a confined facility. The wastewater discharged from fish hatcheries can contain:

• Uneaten fish food
• Fish feces
• Nutrients (especially phosphorus)
• Algae
• Parasites and pathogens
• Drugs and other chemicals
• Warm water

These discharges can lead to changes in water temperature and levels of dissolved gas, pH, phosphorus, nitrogen, and sediment in the receiving water. For example, when flushed into waterways, solid by-products, such as fecal matter and waste food particles, can settle downstream of the facility. These solids increase turbidity (cloudiness) of streams, decrease oxygen in water, and add nutrients. The nutrients then encourage the growth of aquatic plants. The aquatic plants change the habitat and consume oxygen in the water that fish and other plants need to survive.

If left unchecked, discharges into surface waters may result in exceedances of state water quality standards and adversely affect designated beneficial uses. Improper disposal of aquaculture wastes or improperly designed settling ponds or storage lagoons may also cause ground water contamination. Good waste management and water stewardship are necessary to ensure the quality of water in receiving streams.

Aquaculture Regulation in Idaho

Several agencies regulate the aquaculture industry in Idaho.

An aquaculture facility that meets certain criteria or that EPA has determined needs a permit is required to have a National Pollutant Discharge Elimination System permit prior to beginning to discharge. In Idaho, these permits are issued by the EPA. Learn more.

Commercial aquaculture facilities must also be licensed by the Idaho State Department of Agriculture.  As a condition of licensing, all commercially licensed aquaculture facilities must have their effluent control facilities approved by DEQ. Idaho Department of Agriculture regulations cover the disposal of dead fish from aquaculture facilities as well.

DEQ is responsible for protecting surface and ground water quality in Idaho. It issues §401 water quality certifications as part of the NPDES permitting process. A §401 certification states that any discharge will comply with the Clean Water Act and will not cause an exceedance of state water quality standards. DEQ also performs NPDES inspections of aquaculture facilities under contract with EPA. DEQ staff review plans and specifications for aquaculture waste treatment systems and provide technical assistance to aquaculture facility operators regarding waste management practices.

An aquaculture facility must obtain a water right from the Idaho Department of Water Resources (IDWR) to divert or appropriate water for fish propagation. A water right may be acquired by obtaining a permit to appropriate water or by purchasing an existing water right and transferring its designated use to fish propagation. A stream channel alteration permit, also issued by IDWR, may be required for construction or modification of new or existing facilities.

The Idaho Department of Fish and Game and other state and federal agencies also have roles in regulating aquaculture in Idaho.

Aquaculture Facilities and TMDLs

A total maximum daily load (TMDL) is a water quality improvement plan that provides a calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards. TMDLs are calculated for water bodies that do not meet these standards; their purpose is to improve poor water quality. In Idaho, many of the water bodies that support aquaculture facilities have TMDLs prepared for them. When this is the case, a "wasteload allocation" (usually in pounds per day of a particular pollutant) is assigned to each facility on that water body.

Aquaculture Waste Management

Responsible environmental stewardship is critical to sustainable aquaculture. A large part of this stewardship is properly managing waste from the aquaculture facility. To do so, aquaculture facilities should be:

• Designed, built, and maintained in a manner that works toward the elimination of the release of nutrients and solids to surface or ground water;
• Operated in a manner that minimizes the creation of nutrients and solids while providing optimal fish rearing conditions; and
• Managed to collect the wastes to reuse the nutrients (such as for fertilizer) while minimizing the potential of the nutrients impacting ground or surface waters.

A BMP plan for waste management is required for a facility to be covered under Idaho's general NPDES permit for aquaculture. The plan must be tailored to each operation and site because of unique site characteristics, water quality goals, customized facility practices, and management operations objectives. Properly implemented BMPs can reduce or even prevent pollution generated from aquaculture production facilities.

In 2004, EPA finalized effluent limitation guidelines and new source performance standards for the "concentrated aquatic animal production point source category" (40 CFR Part 451). Those facilities subject to the guidelines must develop and maintain a BMP plan describing how they will achieve the requirement. The permittee must certify in writing to EPA that a BMP plan has been developed and make the plan available upon request. Federal guidance for complying with EPA's effluent limitations guidelines is forthcoming.

The Idaho Waste Management Guidelines for Aquaculture Operations provide assistance in developing an effective BMP plan and also define the minimum acceptable construction criteria for building new or upgrading old aquaculture waste treatment systems in order to be approved by the state of Idaho (Idaho Code 39-118).