9 Chequamegon Bay = waters within the region enclosed by Chequamegon Point and a straight line west to the mainland

NR 102.26(1)(1) Development of site-specific ambient temperatures. An owner or operator of a facility with a discharge subject to regulation under this chapter may submit a request to the department for the determination of a site-specific ambient temperature. The department may approve, disapprove or approve with modifications the request for the site-specific ambient temperature. The request for site-specific ambient temperatures shall include all of the following:

NR 102.26(1)(a)(a) A demonstration that the data used to derive the ambient temperatures in s. NR 102.25 do not apply to the specific water segment or body in question.

NR 102.26(1)(b)(b) Site-specific water temperature that represents the ambient temperature of the site. For purposes of this paragraph, data must be:

NR 102.26(1)(b)1.1. Collected daily using a continuous recorder or similar device that takes measurements at least hourly, except as follows:

NR 102.26(1)(b)1.a.a. Monthly data sets may be missing no more than 10 days of temperature data for the months of December through February,

NR 102.26(1)(b)1.b.b. Monthly data sets may be missing no more than 5 days of temperature data for the months of March through November.

NR 102.26(1)(b)2.2. Collected for each month in which the request for site-specific ambient temperatures is requested,

NR 102.26(1)(d)(d) Calculated monthly average temperatures from the daily average temperatures in par. (c) for each individual month that data has been collected. Alternatively, calculated monthly average temperatures directly from the data from par. (b) for each individual month.

NR 102.26(1)(f)(f) A determination of the monthly site-specific ambient temperatures by calculating the geometric mean of all monthly averages for each given month.

NR 102.26(1)(g)(g) Alternative methods for developing site-specific ambient temperatures, if the department approves the method as representative of ambient temperatures as those in pars. (a) to (d).

NR 102.26(2)(2) Use of site-specific ambient temperatures to establish acute criteria. Once site-specific ambient temperatures have been approved by the department in accordance with sub. (1), the acute water quality criteria listed in Table 6 will be applicable for the protection of fish and other aquatic life.

NR 102.26(3)(3) Use of site-specific ambient temperatures to establish sub-lethal criteria. Once site-specific ambient temperatures have been approved by the department in accordance with sub. (1), the sub-lethal water quality criteria applicable for the protection of fish and other aquatic life shall be calculated as follows:

NR 102.26(3)(a)(a) Use Table 7 to determine the appropriate sub-lethal criteria for the fish and other aquatic life use.

NR 102.26(3)(b)1.1. If a sub-lethal criterion from par. (a) is less than the site-specific ambient temperature from sub. (1) for a given month, increase the sub-lethal criterion to be equal with the site-specific ambient temperature.

NR 102.26(3)(b)2.2. If a sub-lethal criterion from par. (a) is greater than an acute criterion for a given month from sub. (2) decrease the sub-lethal criterion to be equal with the acute criterion.

NR 102.26(3)(c)(c) Perform a fifth order polynomial regression of the 12 monthly sub-lethal criteria resulting from par. (b). Using the resulting equation of the regression, calculate the final sub-lethal criteria for each month by replacing the “x” variables in the equation with a numeric representation for each month, where January “x” = 1, for February “x” = 2, … and for December “x” = 12.

NR 102.26(3)(d)(d) The final sub-lethal criteria from par. (c) shall be used in combination with the site-specific ambient temperatures developed in sub. (1) and the acute criteria determined in sub. (2).