Quick Facts
DNR Lake Number: 70002600
Surface Area: 940 acres
Average Depth: 13 feet
Maximum Depth: 56 feet
Ordinary High Water Level: 903.9 feet above sea level
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).
Watershed Area: 18,904 acres
Public Boat Access: Located on the northern side of the lake from Sand Point (off of Crest Avenue).
Impairment Status:
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.
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.
In order to reduce flood potential, the Low-Flow Gate was opened on March 26, 2018 to create storage capacity in the lake for snow-melt and spring rains. The Low-Flow Gate will be closed when the lake reaches 902.0′ or on April 30, 2018; whichever comes first. If you are interested in the approximate amount of flow discharging through the outlet structure when the Low-Flow Gate is open, click here. Otherwise, scroll down to the Flow section to see approximate flow when the Low-Flow gate is closed.
For more information about the Outlet Structure, click here.
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.
Water Quality
The following graphs represent the annual averages between May 1 and September 30.
Current Projects
Completed Projects
- Lower Prior Lake Protection Projects
- Fish Point Park Water Quality Improvement Project (2015-17)
- Indian Ridge Bio-Infiltration basin (2016)
- Fairlawn Shores Bio-Infiltration basin (2017)
- Watzl’s Beach Shoreline Restoration (2015)
- Lower Prior Diagnostic Study (2013)
Reports and Studies
- Article: Prior Lake Elevation Analysis
- Prior Lake Historic Elevations Graph 1970-2015
- 1993 Diagnostic & Feasibility Study of Spring and Prior Lakes
Lake Vegetation Reports
- 2017 Upper and Lower Prior Lake Curlyleaf Pondweed Report
- 2008 Curlyleaf and Eurasian Watermilfoil Growth Potential based on Lake Sediment Characteristics for Spring, Fish, Upper Prior, and Lower Prior Lakes
- 2016 Upper and Lower Prior Lake Curlyleaf Pondweed Assessment
- 2016 Upper and Lower Prior Lake Aquatic Plant Evaluation
- 2015 Upper and Lower Prior Lake Curlyleaf Pondweed Assessment and Aquatic Plant Survey
- 2014 Upper and Lower Prior Lake Curlyleaf Pondweed Assessment
- 2013 Upper and Lower Prior Lake Curlyleaf Pondweed Assessment
- 2012 Upper and Lower Prior Lake Curlyleaf Pondweed Assessment
- 2011 Upper and Lower Prior Lake Curlyleaf Pondweed Assessment
- 2010 Upper and Lower Prior Lake Curlyleaf Pondweed Assessment
