Minn. R. Part 7050.0224
The numeric and narrative water quality standards in this part prescribe the qualities or properties of the waters of the state that are necessary for the agriculture and wildlife designated public uses and benefits. Wild rice is an aquatic plant resource found in certain waters within the state. The harvest and use of grains from this plant serve as a food source for wildlife and humans. In recognition of the ecological importance of this resource, and in conjunction with Minnesota Indian tribes, selected wild rice waters have been specifically identified [WR] and listed in part 7050.0470, subpart 1. The quality of these waters and the aquatic habitat necessary to support the propagation and maintenance of wild rice plant species must not be materially impaired or degraded. If the standards in this part are exceeded in waters of the state that have the Class 4 designation, it is considered indicative of a polluted condition which is actually or potentially deleterious, harmful, detrimental, or injurious with respect to the designated uses.
The quality of class 4A waters of the state must be such as to permit their use for irrigation without significant damage or adverse effects upon any crops or vegetation usually grown in the waters or area. In addition, the following standards apply:
Substance, Characteristic, or Pollutant | Class 4A Standard |
Boron (B) | 0.5 mg/L |
Sulfates (SO4) | 10 mg/L, applicable to water used for production of wild rice during periods when the rice may be susceptible to damage by high sulfate levels. |
Radioactive materials | Not to exceed the lowest concentrations permitted to be discharged to an uncontrolled environment as prescribed by the appropriate authority having control over their use. |
Items A and B apply to the quality of class 4A waters of the state, with the exception of the numeric sulfate standard applicable to waters used for production of wild rice.
Substance, Characteristic, or Pollutant | Class 4B Standard |
pH, minimum value | 6.0 |
pH, maximum value | 9.0 |
Total dissolved solids | 3,000 mg/L |
Nitrate + nitrite (as NO3+NO2-N) | 100 mg/L |
Sulfate (SO4) | 600 mg/L |
Radioactive materials | Not to exceed the lowest concentrations permitted to be discharged to an uncontrolled environment as prescribed by the appropriate authority having control over their use. |
Toxic substances | None at levels harmful either directly or indirectly |
Minn. R. Part 7050.0224
Statutory Authority: MS s 115.03; 115.44