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Prior Lake Spring Lake Watershed District

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DNR Lake Number: 70007200

Quick Facts

Surface Area

386 acres

Ordinary High Water Level*

903.9 feet above sea level

Average Depth

10 feet

Watershed Area

16,038 acres

Maximum Depth

43 feet

Connectivity to other waterbodies

Water flows into Upper Prior from Spring Lake through the Spring-Prior connecting channel. Water flows from Upper Prior into Lower Prior Lake.

Bridge Clearance

The elevation at the bottom of Wagon Bridge (bridge under Highway 21) is approximately 911.5′. Subtract the current lake elevation from 911.5′ to get the approximate clearance.

Aquatic Invasive Species

Zebra mussel, Eurasian watermilfoil, Curlyleaf pondweed, common carp, Chinese mystery snail

High Water No-Wake Restrictions

When lake level exceeds 903.9 feet (see notes below)

Impairment Status

Impaired for Mercury, Biota, and Excess Nutrients (see notes below)

View Lake Level

Maps

Prior Lake, Upper map image

Historical Lake Levels

The graph below displays the average of annual lake level readings, when available.  Some years only had one lake level measurement so those would not reflect the “average” and could have been taken at any time of year.  Also, some years are missing from this graph because there is no known data available.  The red line indicates when the weir was installed.  Prior to the red line, there was no natural outlet for Prior Lake.

historic lake levels graph

Water Quality

Click on each image below to view in a larger size
Water quality report card cover
Water quality report card back

This graph represents the annual averages of water quality parameters between June 1 and September 30.

Historic average

This graph show water quality parameters on specific dates in 2024.

Related Resources

Ongoing Projects

Completed Projects

Upper Prior Lake Alum Treatment

Status: Completed

Studies by the Prior Lake-Spring Lake Watershed District determined Upper Prior Lake was impaired/threatened by an excess of phosphorus and…
View project
Boudin Neighborhood Improvement Project

Status: Completed

Prior Lake-Spring Lake Watershed District completed retrofit projects on the Boudin neighborhood reconstruction that previously drained untreated to…
View project
  • No-Wake restrictions are set by the City of Prior Lake and enforced by the Scott County Sheriff. Once high water levels have subsided and remained below the no-wake level (903.9 ft) for 72 hours, no-wake restrictions will be lifted. For more details, view the full city ordinance
  • Mercury impairments are not handled at the local government level.  The State of MN has a TMDL they are following here.
  • Biota impairments are not handled at the local government level.  The State of MN addresses impaired biota by examining the interactions of numerous physical, chemical, and biological processes that define community composition. Biological impairments can be driven by natural or unnatural changes to one or many components of these systems. Biological impairments differ from some traditional water quality  impairments in that the impaired biotic communities are indicators of disturbance rather than causes of disturbance.  Biological impairments are commonly caused by stressors that are not considered conventional pollutants. These include stressors such as degraded habitat or altered hydrology. Minnesota utilizes the process of stressor identification developed by the EPA to identify the dominant stressors.
  • See the TMDL study for more information.