Prior Lake, Lower | Prior Lake Spring Lake Watershed District

Quick Facts

DNR Lake Number: 70002600
Surface Area: 956 acres
Average Depth: 13 feet
Maximum Depth: 56 feet
Ordinary High Water Level: 903.9 feet above sea level
High Water No-Wake Restrictions: When lake level exceeds 903.9 feet*
Watershed Area: 18,904 acres
Impairment Status: Impaired for mercury** and biota***
Connectivity to other waterbodies: Water flows into Lower Prior from Upper Prior. The lake level is controlled by the outlet structure which feeds the Prior Lake Outlet Channel (PLOC).
Public Boat Access: Sand Point (off of Crest Avenue on north side of 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.

*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.

**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.

Lake Levels

All lake level data below are approximate and preliminary – NOT to be used for legal purposes. Sudden drops or spikes are often due to calibration, which are manual adjustments to correct the lake level value. Please contact the PLSLWD office for official readings.

Note: The main gate and the low flow gate of the outlet structure are OPEN. To facilitate bank erosion repair work downstream in the outlet channel, the main gate on the outlet structure was temporarily closed during part of October but was reopened by the end of the month.

For more information about the Outlet Structure, click here.

Occasionally, especially during cloudy weather, the level logger does not get service and the lake level does not get updated automatically on the graph below. This can sometimes go on for a couple days and there is nothing we can do. If you need to know the lake level, you can check the staff gauge on the NW pillar of Wagon Bridge (Hwy 21 bridge crossing Prior Lake, across the road from Knotty Oar Marina). Just add 900 to the number that you see to get the mean sea elevation.

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 no known data is available. The red line indicates when the weir was installed. Prior to the red line, there was no natural outlet for Prior Lake.

Flow

Estimated flow through the Prior Lake outlet structure based on past measurements of lake level and discharge. Note that the data is only valid for lake elevations between 902.5 and 903.75 and when the low-flow gate is closed. Use this table to estimate flow when low-flow gate is open. Stream discharge is calculated in cubic feet per second (cfs).

Water Temperature

Sensor is located in a well at the outlet structure roughly 2 feet into the lake sediment, so temperatures will not reflect surface conditions exactly.