Water Monitoring and Surveys

The Water Monitoring and Surveys Unit collects data and provides information about stream flows in Minnesota. This information helps the DNR and others carry out statutory responsibilities and water management programs.

The DNR Commissioner has given the DNR Ecological and Water Resources Division Director authority to administer the majority of the state water law contained in Minnesota Statutes, Chapter 103G. Chapter 103G gives the commissioner authority to regulate work in public waters; control water appropriation and use; ensure the safety of dams; and conduct water resource surveys, investigations and studies.

Specifically, Section 103G.285, Subdivision 2 makes the commissioner responsible for limiting water withdrawals from streams during low flow conditions:

  • If data are available, permits to appropriate water from natural and altered natural watercourses must be limited so that consumptive appropriations are not made from the watercourses during periods of specified low flows. The purpose of the limit is to safeguard water availability for instream uses and for downstream higher priority users located reasonably near the site of appropriation.

Clientele, Products, and Services


Primary clientele are DNR Ecological and Water Resources technical staff, supervisors, and managers who need stream flow information to make permit decisions. Secondary clientele include technical staff in other DNR divisions, other agencies, local governments, consulting engineering firms, and members of the public needing stream flow information for planning and management decisions.

Requests for stream gauging assistance come from DNR field hydrologists, other state agency staff, and local governments and watershed organizations. The Water Monitoring and Surveys Unit receives more requests than they can serve, so project priorities must be determined.


  • Production and distribution of weekly statewide stream flow conditions reports during the open water season (typically April through October)
  • Production of stream discharge and elevation hydrographs
  • Technical reports analyzing hydrology for special projects
  • Technical guidance materials explaining stream flow measurement techniques
  • Production and distribution of daily stream flow conditions reports during severe drought or flood events


  • Accessing and interpreting data from more than 70 stream flow network gauges during the open water season
  • Taking miscellaneous stream flow measurements at key locations during severe drought or flood events
  • Making periodic stream flow measurements and establishing and maintaining stream elevation-discharge curves for special projects and flood forecast/warning gauges
  • Providing information on low-flow conditions to the division director and Water Use Management Unit for decisions about suspension of surface water appropriations
  • Reviewing and making recommendations on hydropower licensing and relicensing applications submitted to the Federal Energy Regulatory Commission
  • Providing historical stream flow and stage information and flow statistics,
  • Monitoring operation of 10 hydropower facilities for compliance with federal licenses and state water permits
  • Applying hydrologic models to problems involving surface/ground water interactions.

Information Management

The Water Monitoring and Surveys Unit uses a unique database and processing software known as HYDSTRA for storage and management of the data from the network of stream gages.

The HYDSTRA system stores DNR stream data, and the Minnesota Pollution Control Agency (MNPCA) stream data. This is the first time the DNR and MNPCA are archiving stream data in the same location. Other DNR divisions and outside cooperators have expressed interest in sharing this data system as well.

HYDSTRA is a collection of database management tools and hydrologic software packages that allows users to store and organize historical data, graphically analyze and edit hydrologic data, store and access digital photos, maps and other documents associated with stream files. HYDSTRA also offers various output formats, both graphical and tabular, to share stream data with others.

Flood forecast/warning system gage data are automatically downloaded into HYDSTRA via a satellite link. Stream flow and stage data collected at DNR special project sites or reported to DNR by hydropower facility operators are also stored in HYDSTRA. DNR floodwarning gage data can be accessed at the DNR/MPCA Cooperative Stream Gaging Web page and a National Weather Service Web site.


  • Gage locations, site characteristics, reader, type, and drainage area
  • Benchmark information
  • Flow measurements
  • Stage gage readings and electronic readings
  • Rating curves, rating tables
  • Computed stream flows
  • Hourly headwater and tailwater readings
  • Flow statistics
  • Electronic documents including: photos, maps, schematics, etc.



St. Paul

Detroit Lakes

Grand Rapids