31.34 Flow of water regulated.

(1) Except as provided in subs. (2) and (3), each person, firm, or corporation maintaining a dam on any navigable stream shall pass at all times at least 25 percent of the natural low flow of water of such stream.

(2) Except as provided in sub. (3), if all of the following apply to a dam on a navigable stream, the person, firm, or corporation maintaining the dam shall pass an amount of water not less than the lesser of the low flow of the stream over the preceding 10-year period, as determined using the 7-day, 10-year low-streamflow method, or the amount of water passed by groundwater seepage and leakage through the dam structure:

(a) The dam is in a location where a dam was originally constructed prior to 1845 and regulates water discharge to a stream from a lake with a depth of over 125 feet.

(b) The precise level of the natural low flow of water at the location of the dam prior to its construction is not known.

(c) Historically there have been extended periods during which water passed through the dam only as groundwater seepage and as the result of leakage through the dam structure.

(2m) The department may not order a person, firm, or corporation maintaining a dam described under sub. (2) (a) to (c) to pass an amount of water greater than the minimum discharge described under sub. (2).

(3) The requirements under subs. (1) and (2) do not apply to any of the following:

(a) A plant or dam where the water is discharged directly into a lake, mill pond, storage pond, or cranberry marsh.

(am) A dam, in existence on June 25, 2017, in a commercial fish farm, in existence and registered with the department of agriculture, trade and consumer protection on June 25, 2017, and located in Langlade County, where the water is returned to the navigable stream.

(b) Cases in which, in the opinion of the department, the applicable minimum discharge described in sub. (1) or (2) is not necessary for the protection of fish life.

(4) Any person, firm, or corporation violating this section shall be fined not less than $50 nor more than $1,000.

History: 2015 a. 55; 2017 a. 21.