(a) Aquatic animal production facilities, as defined in this section, are point sources subject to the NPDES permit program. Concentrated aquatic animal production facilities are subject to the individual permit program. Other animal production facilities are subject to the general permit program. (§ 122.48.)
(b) Definitions. Aquatic animal production facility means a hatchery, fish farm, or other facility which contains:
(1) Any species of fish or other aquatic animal [other than carp (Cyprinus carpio), goldfish (Carassius auratus), or brown trout (Salmo trutta)] nonnative of the United States and from which there is a discharge at any time; or
(2) Fish or other aquatic animals in ponds, raceways or other similar structures for purposes of production, which are not closed ponds discharging only during periods of excess runoff, and which discharge at least 30 days per year. . . .
(3) Concentrated aquatic animal production facility means any aquatic animal production facility, as defined in subparagraph (1) of this paragraph which:
(i) Produces more than 20,000 pounds of aquatic animals per year; or
(ii) Is designated by the Enforcement Division Director as a significant contributor of pollution to the waters of the United States in accordance with paragraph (c).
(c) Case-by-case designation of concentrated aquatic animal production facilities.
Id. (emphasis added).
Most commercial fish husbandry that the layperson refers to as aquaculture, including fish farms located in waters of the U.S., is subject to NPDES regulation under the rubric concentrated aquatic animal production facility. As with feedlots, an aquatic animal production facility is subject to regulation under the NPDES permitting program only if the facility is concentrated according to the NPDES regulations.
Subpart CNet Pen Systems
§ 451.30 Applicability.
This subpart applies to the discharge of pollutants from a concentrated aquatic animal production facility that produces 100,000 pounds or more per year in net pen systems, except for net pen facilities located in the State of Alaska producing native species of salmon.
§ 451.31 Effluent limitations attainable by the application of the best practicable control technology currently available (BPT).
Except as provided in 40 CFR 125.30 through 125.32, discharges from a net pen system subject to this subpart must achieve the following best management practice representing the application of BPT:
(a) The permittee must maintain a real-time monitoring system to monitor the rate of feed consumption. The system must be designed to allow detection or observation of uneaten feed passing through the bottom of the net pens and to prevent accumulation.
. . .
§ 451.35 Best Management Practices (BMPs).
Any net pen system subject to this subpart must develop and implement a Best Management Practices (BMP) plan to achieve the following specific requirements:
(a) The permittee must operate the facility so as to minimize the concentration of net-fouling organisms that are discharged, for example, changing and cleaning nets and screens onshore.
(b) The following discharges into waters of the United States should be avoided to the maximum extent feasible:
(1) Blood, viscera, fish carcasses, or transport water containing blood associated with the transport or harvesting of fish;
(2) Substances associated with in-place pressure washing nets. The use of air-drying, mechanical, and other non-chemical procedures to control net fouling are strongly encouraged.
(c) The permittee must develop and implement practices to minimize the potential escape of non-native species.
(d) The following discharges from a net pen system into waters of the United States are prohibited:
(1) Feed bags and other solid wastes;
(2) Chemicals used to clean nets, boats or gear; and
(3) Materials containing or treated with tributyltin compounds.
Id. at 57,928.