Protected flow

Minnesota Rules 6115.0630 Subp. 12
"'Protected flow' is defined as the amount of water required in the watercourse to accommodate instream needs such as water-based recreation, navigation, aesthetics, fish and wildlife habitat, water quality, and needs by downstream higher priority users located in reasonable proximity to the site of appropriation."


Protection flow for "instream needs" has been identified as a significant social and environmental issue. Instream flow protection is addressed in Minnesota Statutes, and permits issued for appropriation of water from streams or lakes may be limited in order to maintain and protect instream uses. Consumptive appropriations are not allowed when flows are below specified low flows.

Minnesota is widely perceived as a water-rich state. The apparent abundance of water can create an illusion that water will be available for all demands. Even more difficult to imagine is that there could be a statewide shortage. In 1988, this complacency was rudely shattered as flow levels in streams, lakes, and aquifers decreased dramatically. Minnesota and much of the Upper Midwest was in the throes of a severe to extreme drought, rivaling the drought conditions of 1933-1934. Wells went dry, streams had low or no flow, and the lack of adequate water supplies affected all users, out-of-stream and instream. (For more information on evaluating drought severity, see Monitoring Drought Conditions.)

Surface-water appropriators who had never before experienced water availability shortages had their surface water appropriation permits suspended as early in the season as June, 1988. Their livelihoods were threatened as water levels in watershed after watershed reached historic lows. The permits were suspended because stream flows had reached or fallen below their protected levels.

Is Minnesota, "the land of 10,000 lakes," truly water rich? Perhaps. But the flowing water resources of the state remain subject to the vagaries of nature and demands of its citizens. We cannot control nature. We can only strive to manage demand and the stresses natural variations in water supply place on our use of water resources.

Instream Flows/Protected Flows

Instream Flow is a segment of the River Ecology Unit and is a Department of Natural Resources cooperative program that is being developed by the DNR Divisions of Ecological Resources and Waters for the protection of fish and wildlife, recreation, and other instream uses. This is an emerging program that is in the research and rule formulation stage.

The instream flow element, through ongoing research and data collection, identifies and quantifies stream flow levels that are optimal for fish and wildlife, recreation, and other instream uses. The protected flow portion is the regulatory program element that monitors stream flows and manages current conditions through the appropriations permit program to meet instream needs.

Until specific protected flows have been established, the DNR Divisions of Ecological Resources and Waters have agreed to use the annual 90 percent exceedance flow for all new permits for water appropriations from streams.

Past Accomplishments

  • Field data collection and research continues.
  • The gaging and monitoring network is growing, and data quality and availability enhancements continue (floodwarning system gages installed and collecting data).
  • A program development process plan is being renewed.
  • Technical assistance continues to be provided for an increasing number of projects and studies related to water quality, locally as well as at the state agency level.
  • Stream flow monitoring reports are produced weekly during the open water season and daily during periods of extreme conditions.
  • Research continues as to how to apply gaged data to managed sites.
  • Modeling is advancing from using a one-dimensional computer habitat model to a two-dimensional model.
  • More effort is being given to evaluating flows needed for shaping and maintaining channel morphology.

Future Directions.

The DNR Divisions of Ecological Services and Waters will be working together to develop an educational program to inform and promote public involvement in instream flow issues. Greater recognition that water quantity greatly affects water quality has created a need to expand our flow monitoring program.

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