Bureau of Water Quality – WY/3
PO Box 7921
Madison WI 53707
Madison: Department of Natural Resources, 101 S. Webster St., Madison, WI 53707, Room G09
Green Bay: DNR Service Center, 2984 Shawano Ave, Green Bay WI 54313, Lake Michigan Room
Section 1. NR 102.03 (intro.) is amended to read:
NR 102.03 Definitions. In this chapter, the following definitions are applicable to terms usedapply:
Section 2. NR 102.03 (1c), (1e), (1g), (1i), (1k), (1m), (1q), (1v), (6d), and (9) are created to read:
NR 102.03 (1c) “Benthic” means relating to the ecological zone at the bottom of a body of water, including the sediment surface and subsurface layers.
(1e) “Biocriterion” means a surface water quality criterion under subch. III that describes the structure and function of aquatic communities in a waterbody necessary to protect its designated aquatic life use.
(1g) “Chlorophyll a” means a green pigment present in all green plants and in cyanobacteria, responsible for the absorption of light to provide energy for photosynthesis.
(1i) “Clean Water Act” means the federal Clean Water Act of 1972 and amendments.
(1k) “Confidence interval” means a range within which the true value of a parameter is likely to occur, with a specified level of confidence.
(1m) “Diatom” means a common and diverse group of unicellular algae of the phylum Chrysophyta, having cell walls containing silica.
(1q) “Impounded flowing water” means a waterbody impounded by a constructed outlet structure on a river or stream that is not a reservoir as defined in sub. (4m).
(1v) “Macrophyte” means an aquatic plant large enough to be seen without the use of a microscope.
(6d) “Section 303 (d) list” means a list of waters that do not attain water quality standards and require a total maximum daily load analysis, as specified under section 303 (d) of the Clean Water Act, 33 USC 1313 (d). (9) “U.S. EPA” means the United States environmental protection agency.
Section 3. NR 102.04 (4) (a) is repealed and recreated to read:
NR 102.04 (4) (a) Dissolved oxygen. 1. For streams, rivers, and impounded flowing waters, dissolved oxygen criteria apply to samples taken from the main channel near the area with greatest flow. For lakes or reservoirs, the dissolved oxygen criteria in this paragraph apply to the epilimnion of stratified lakes and to all but the deepest one meter of the water column of unstratified lakes.
2. Except as provided in subds. 3. to 7. and par. (am), surface waters shall attain a minimum dissolved oxygen concentration of 5 mg/L at all times.
3. A waterbody classified by the department as a trout class I or II water under s. NR 1.02 (7), a cold water community that is not a two-story fishery lake covered under par. (am), or a great lakes tributary used by salmonids for spawning during the period of habitation, shall attain all of the following: a. A minimum dissolved oxygen concentration of 6.0 mg/L at all times.
b. A minimum dissolved oxygen concentration of 7.0 mg/L when cold water fish are spawning through fry emergence from their redds, or gravel nests.
Note: The period from spawning through fry emergence from their gravel nests is approximately mid-October through April, but varies depending on water temperature and location in the state.
c. Dissolved oxygen concentrations and diurnal patterns may not be altered from natural background levels to such an extent that cold water populations are adversely affected.
4. A waterbody classified by the department as trout class III under s. NR 1.02 (7) shall attain a minimum dissolved oxygen concentration of 6.0 mg/L at all times. 5. A waterbody for which a use attainability analysis under 40 CFR 131.10 (g) (1) to (6) demonstrates that its otherwise applicable designated use category is unattainable shall attain the following: a. For a waterbody otherwise designated as a coldwater community, a minimum dissolved oxygen concentration of 5 mg/L at all times.
b. For any other community, a minimum dissolved oxygen concentration of 3 mg/L at all times.
Note: Waterbodies described in subd. 5 are also known as altered warmwater or altered macroinvertebrate waters.
6. A waterbody designated by the department as limited forage fish shall attain a minimum dissolved oxygen concentration of 3 mg/L at all times.
7. A waterbody designated by the department as limited aquatic life or wetlands, or classified as diffuse surface waters or wastewater effluent channels shall attain a minimum dissolved oxygen concentration of 1 mg/L at all times when water is present.
Section 4. NR 102.04 (4) (am) is created to read:
NR 102.04 (4) (am) Oxythermal layer thickness for two-story fishery lakes. 1. ‘Criteria.’ A two-story fishery lake shall maintain, during its period of summer stratification, an oxythermal layer of at least 1 meter in thickness that maintains both a dissolved oxygen concentration of at least 6 mg/L and a maximum temperature of the following:
a. For a two-story fishery lake with lake trout, 57° F or less.
b. For a two-story fishery lake with whitefish but not lake trout, 66° F or less.
c. For a two-story fishery lake with cisco but not whitefish or lake trout, or that the department manages for brook, brown, or rainbow trout, 73°F or less.
d. For a two-story fishery lake with multiple coldwater fish species, the applicable criterion under subd. 1. a. to c. is that for the lake’s species requiring the lowest temperature.
2. ‘Assessment.’ a. The monitoring period for the criteria under subd. 1. is June 1 to September 15. When monitoring for assessment purposes, depth profiles of temperature and dissolved oxygen shall, whenever possible, be taken in increments of 1 meter or less near the deepest part of the lake, at least monthly July to September.
Note: Reservoirs, multi-lobed lakes, or very large lakes may need more than one sampling station to assess the lake.
b. During any given year, if at any point the applicable criterion in subd. 1. is not met, that year is an exceedance year. If more than one third of years sampled within the most recent 10-year period are exceedance years, the lake is not attaining the water quality criterion and shall be listed on the section 303 (d) list.
Section 5. NR 102.04 (4) (b) is repealed.
Section 6. NR 102.04 (4) (d) is amended to read:
NR 102.04 (4) (d) OtherToxic substances. Unauthorized concentrations of substances are not permitted that alone or in combination with other materials present are toxic to fish or other aquatic life. Surface waters shall meet the acute and chronic criteria as set forth in or developed pursuant to ss. NR 105.05 and 105.06. Surface waters shall meet the criteria which correspond to the appropriate fish and aquatic life subcategory for the surface water, except as provided in s. NR 104.02 (3). Section 7. NR 102.04 (4) (f) and (g) are created to read:
NR 102.04 (4) (f) Chlorophyll a. 1. ‘Criteria.’ a. Mean suspended chlorophyll a concentrations in lakes and reservoirs other than stratified two-story fishery lakes shall not exceed 27 ug/L.
b. Mean suspended chlorophyll a concentrations in stratified two-story fishery lakes shall not exceed 10 ug/L.
2. ‘Assessment.’ Data requirements are the same as those specified in s. NR 102.07 (1) (a) 1., except that the sampling period for chlorophyll a is July 15 to September 15. To determine attainment of the chlorophyll a criterion under subd. 1., the department shall compare the waterbody’s mean suspended chlorophyll a concentration during the sampling period to the criterion, using the confidence interval approach described under s. NR 102.52 (2) (b) to (c) to determine if additional samples are needed. Note: The aquatic life chlorophyll a criteria do not apply to streams, rivers, or impounded flowing waters, as they were established based on lake trophic status levels.
(g) Other criteria. Surface waters shall meet all other criteria that correspond to the appropriate aquatic life subcategory for the surface water, including narrative criteria specified in sub. (1) and biocriteria described in subch. III.
Section 8. NR 102.04 (5) (b) is amended to read:
NR 102.04 (5) (b) Exceptions. Whenever the department determines, in accordance with the procedures specified in s. NR 210.06 (3), that wastewater disinfection is not required to protect recreational uses, the criteria specified in par. (a)sub. (6) (a) and in chs. NR 103 and 104 do not apply. Section 9. NR 102.04 (6) is renumbered (6) (a).
Section 10. NR 102.04 (6) (a) (title), (b), and Table A are created to read:
NR 102.04 (6) (a) (title) Bacteria.
(b) Frequency of moderate algae levels. 1. ‘Criteria.’ A moderate algae level is defined as a chlorophyll a concentration of 20 ug/L or greater. Lakes, reservoirs, and impounded flowing waters shall not exceed the frequency of moderate algae levels specified in Table A during the summer sampling period.
Table A
Recreational use criteria for frequency of moderate algae levels
Waterbody Type1 | Subcategory | Criteria for frequency of moderate algae levels |
Lakes, Reservoirs, Impounded Flowing Waters (includes cold and warm) | Impounded flowing water, Unstratified drainage, Unstratified seepage | Does not exceed 20 ug/L chlorophyll a for more than 30% of days during the summer sampling period2 |
| Stratified drainage, Stratified seepage | Does not exceed 20 ug/L chlorophyll a for more than 5% of days during the summer sampling period2 |
| Stratified two-story fishery | |
1 Terms used for waterbody types and subcategories are defined in s. NR 102.03. 2 Summer sampling period is July 15 to September 15.
Note: Lakes and reservoirs are subcategorized based on both their stratification status (stratified vs. unstratified) and whether or not they have an outlet stream or river (drainage vs. seepage). To find a lake or reservoir’s subcategory, also known as its natural community, go to the department’s Surface Water Data Viewer online map at https://dnr.wi.gov/topic/surfacewater/swdv/ and turn on the layer for Surface Water: Lake Natural Communities. On the natural communities layer, unstratified is referred to as “shallow”, and stratified is referred to as “deep.” Headwater and lowland lakes are types of drainage lakes. 2. ‘Assessment.’ Data requirements are the same as those specified in s. NR 102.07 (2) (a) 1., except that the sampling period for chlorophyll a in all waterbody types is July 15 to September 15. To determine attainment of the criterion, the department shall statistically determine a waterbody’s frequency of moderate algae levels during the chlorophyll a summer sampling period using the confidence interval approach as described under s. NR 102.52 (2) (b) and (c) and compare that frequency to the applicable criterion in Table A. Section 11. NR 102.06 (1) is amended to read:
NR 102.06 (1) General. This section identifies the water quality criteria for total phosphorus that shall be met in surface waters. Assessment procedures for waterbodies are specified in s. NR 102.07.
