Section 207.05. Determining significant lowering of water quality.

 

(1)   Indicator parameters. For each proposed new or increased discharge the department shall determine a list of water quality parameters for which the significant lowering of water quality test will be applied. The list shall consist of:

(a) Biochemical oxygen demand/dissolved oxygen, ammonia-nitrogen, and copper; or

(b) Some other list of substances for which water quality criteria or secondary values have been determined according to chs. NR 102 to 105 , not to exceed 10 parameters, which is determined to be representative of the discharge.

(2)   Application information. Persons proposing a new or increased discharge shall use the following procedure to demonstrate to the department whether the discharge will result in a significant lowering of water quality:

(a) Determine the expected levels of the indicator parameters in the discharge.

(b) Determine existing levels of the indicator parameters upstream of, or adjacent to, the discharge site using applicable procedures in chs. NR 102 and 106 or specified by the department if none of those procedures apply. Existing levels shall be based on the earliest source of data after March 1, 1989 unless a demonstration is made that there has been a change in existing levels resulting in a change in the assimilative capacity of the receiving water, in which case the existing levels shall be based on the data used in the demonstration.

(c) Calculate expected levels in the receiving water of the indicator parameters as a result of the proposed new or increased discharge. In calculating expected levels in the receiving water, the following shall be used:

1. Applicable design low flow rates or dilution ratios for the receiving water in ch. NR 102 or 106 or specified by the department if none of those rates or ratios apply.

2. The daily average discharge loading rates for the new or increased portion of a municipal discharge or the yearly average discharge loading rates for the new or increased portion of an industrial discharge.

(d) Compare the expected levels in the receiving water of each indicator parameter as calculated in par. (c) to:

1. The assimilative capacity multiplied by one-third for all indicator parameters except dissolved oxygen; or

2. The sum of the existing level multiplied by two-thirds and the water quality criterion multiplied by one-third for dissolved oxygen.

(3)   Procedure waiver. Persons proposing a new or increased discharge may choose to waive the procedure in sub. (2) , and proceed directly to the economic and social development test in s. NR 207.04 (1) (c) .

(4)   Department determinations. The department shall determine that a proposed new or increased discharge will result in a significant lowering of water quality if either:

(a) The proposed new or increased discharge, along with all other new or increased discharges after March 1, 1989, taking into account any changes in assimilative capacity over time that have been demonstrated under sub. (2) (b) , results in an expected level of an indicator parameter in the receiving water of either of the following:

1. Greater than one-third multiplied by the assimilative capacity for any indicator parameter other than dissolved oxygen; or

2. Greater than the sum of the existing level multiplied by two-thirds and the water quality criterion multiplied by one-third for dissolved oxygen.

(b) For a discharge to the Great Lakes system, the mass loading to the receiving water of any substance in the proposed new or increased discharge having a bioaccumulation factor greater than 1000 would be increased.

History: Cr. Register, February, 1989, No. 398 , eff. 3-1-89; am. (1) (b) and (4) (b), Register, August, 1997, No. 500 , eff. 9-1-97.