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Minnesota Legislature

Office of the Revisor of Statutes


Subpart 1.


For purposes of this chapter, the following terms have the meanings given them.

Subp. 2.

Terms defined in statute.

The terms "waters of the state," "groundwater," "water pollution," and "toxic pollutants," as well as any other terms for which definitions are given in the pollution control statutes, as used herein have the meanings given to them in Minnesota Statutes, sections 115.01 and 115.41, with the exception that disposal systems or treatment works operated under permit or certificate of compliance of the agency are not "waters of the state."

Subp. 3.

Seven-day ten-year low flow or 7Q10.


"Seven-day ten-year low flow" or "7Q10 " means the lowest average seven-day flow with a once in ten-year recurrence interval. A 7Q10 is derived by identifying the lowest average flow for a seven-consecutive-day period from daily flow records for each year of record, from a continuous flow gauging station. The seven-day average low flow values for each year are arrayed in order of magnitude and fitted to a probability distribution. The 7Q10 is the stream or river flow that is equal to or exceeded by 90 percent of the values in the distribution.


The period of record for determining the specific flow for the stated recurrence interval, where records are available, shall include at least the most recent ten years of record, including flow records obtained after establishment of flow regulation devices, if any. Where stream flow records are not available, the flow may be estimated on the basis of available information on the watershed characteristics, precipitation, runoff, and other relevant data. The calculations shall not be applied to lakes and their embayments which have no comparable flow recurrence interval.

Subp. 4.


"Commissioner" means the commissioner of the Minnesota Pollution Control Agency or the commissioner's designee.

Subp. 5.

Nonpoint source.

"Nonpoint source" means a land management or land use activity that contributes or may contribute to ground and surface water pollution as a result of runoff, seepage, or percolation and that is not defined as a point source under Minnesota Statutes, section 115.01, subdivision 11.

Subp. 6.

Surface waters.

"Surface waters" means waters of the state excluding groundwater as defined in Minnesota Statutes, section 115.01, subdivision 6.

Subp. 7.

Other terms.

Other terms and abbreviations used in this chapter are defined in the part in which they are used. Terms and abbreviations used in this chapter that are not specifically defined in applicable federal or state law shall be construed in conformance with the context, and in relation to the applicable section of the statutes pertaining to the matter, and current professional usage.

Statutory Authority:

MS s 115.03; 115.44


9 SR 913; 12 SR 1810; 15 SR 1057; 18 SR 2195; 32 SR 1699

Published Electronically:

April 1, 2008