Minnehaha Creek Watershed District

Water Level Update - July 14, 2022

 

In this update:

5th Driest June on Record Exacerbates Low Water Levels & Classifies MCWD with Moderate Drought
Dry conditions across Minnesota began in 2020 and expanded rapidly across the state during the summer of 2021. The Minnehaha Creek Watershed District (MCWD) was classified with moderate drought and severe drought in the summer of 2021. In 2021, the Twin Cities ended the year with 25.96 inches of total precipitation, which is 5.62 inches below normal.

The first half of 2022 has continued this dry trend for the Twin Cities. June 2022 was the Twin Cities’ fifth driest June on record (out of 152 years of precipitation records), with 1.13 inches of rain, which is 3.45 inches below normal.

The U.S. Drought Monitor map for Minnesota is updated every Thursday. Today’s drought map update, shown above, identifies that approximately 3% of the state has been classified with moderate drought, including the Minnehaha Creek Watershed District. The National Oceanic and Atmospheric Administration (NOAA) has identified that as of July 12, 2022, MCWD would need to receive 5.4 inches of rain over a 1-month time frame to end drought conditions.

Precipitation across Minnesota has varied greatly in 2022. As of July 14, 2022, the Twin Cities has received 13.63 inches of precipitation, which is 3.04 inches below normal. The Minnesota Department of Natural Resources (DNR) precipitation map, shown below, shows that MCWD only received 60-70% of its normal precipitation from April 1 – July 12, 2022. Whereas during that same time period, areas just north of the Twin Cities and most of northern Minnesota, received 110-150% of their normal precipitation.

Dry Weather Will Likely Cause Closure of the Gray's Bay Dam

Due to ongoing dry conditions and below normal rain totals, water levels across MCWD are low and many of the streams that drain into Lake Minnetonka are no longer flowing with water. The Gray’s Bay Dam was opened on June 1, 2022 and due to low rain totals and water levels, has been discharging the minimum allowed rate of 12 cubic feet per second (cfs), which is considered the base flow discharge (the portion of stream flow that that is not associated with rainfall events).

Looking ahead to the next couple of weeks, drought conditions are likely to intensify across MCWD, as the National Weather Services’ 6-10 day, 8-14 day (shown below), 1-month, and 3-month outlooks generally forecast below normal precipitation and above average temperatures. Given these weather outlooks, MCWD anticipates that water levels will continue to fall and will likely require the closure of Gray’s Bay Dam over the next week.
The Gray’s Bay Dam operating plan, developed with the DNR and communities across MCWD, lays out six management goals and attempts to replicate historical discharges that would have occurred from Lake Minnetonka. In evaluating historical data, the DNR found that 928.60 feet is the estimated natural runout elevation of Lake Minnetonka. This means historically Lake Minnetonka did not discharge water into Minnehaha Creek when the lake fell below 928.60 feet. Therefore, the dam’s operating plan requires that the dam be closed when the lake falls below 928.60 feet (“Zone 6” in the graphic below).

Lake Minnetonka Water Level

The current level of Lake Minnetonka is 928.72 feet, which is 8.16 inches below the ordinary high water level of 929.40 feet, and 1.44 inches above the runout elevation of 928.60 feet. Due to June 2022 being the fifth driest on record, the graph below shows how Lake Minnetonka’s water level dropped during the month of June.

Current and historical Lake Minnetonka readings and dam discharge rates can be viewed on MCWD’s website. Real-time readings for Lake Minnetonka can be viewed on this U.S. Geological Survey’s (USGS) website.


Minnehaha Creek Flow 

Minnehaha Creek is currently flowing at approximately 14 cubic feet per second at Hiawatha Avenue in Minneapolis. Real-time readings for Minnehaha Creek at Hiawatha Avenue can be viewed on this USGS website. Historical flow and other water data for this station can be viewed on this USGS website

NEW Minnehaha Creek Headwaters Water Level Sensor & Camera

MCWD, in partnership with the USGS, has installed a new real-time water level sensor at the Minnehaha Creek Headwaters wetland (where the dam discharges water from Lake Minnetonka into Minnehaha Creek). Real-time water level readings for the Minnehaha Creek Headwaters can be viewed on this USGS website.

In addition to the real-time sensor, a camera was also installed by the USGS to capture a picture every 60 minutes of the area just below the Gray’s Bay Dam as it enters the Minnehaha Creek Headwaters. An interactive graph with water level readings and camera images can be viewed on this USGS website.

Wild Rice Growing in Minnehaha Creek Headwaters

For the third year in a row, the wild rice population at the headwaters of Minnehaha Creek is flourishing in the low water level conditions. The picture below shows paddlers entering  wild rice growth at the Minnehaha Creek headwaters.   

NEW Tools & Technology Inform Dam Operations

To better track the variability of precipitation and the response it creates across the watershed, MCWD is in the midst of a partnership with Hennepin County Emergency Management (HCEM) to install a real-time sensor network (RESNET) that includes over 20 new real-time water level and flow sensors across the watershed (locations shown below). Coupled with HCEM's Hennepin West Mesonet weather stations, USGS’ real-time sensors, and tailored weather forecasts from the National Weather Service, this network of sensors and forecast data provides an unprecedented level of detail about how much precipitation has fallen across the watershed and how the watershed responds to the precipitation.

In 2021, MCWD developed a machine learning model which uses the remote sensing data from key RESNET locations to optimize the operation of the Gray’s Bay Dam. In 2022, MCWD is using this machine learning model to continue to fine-tune dam operations and balance the needs of Lake Minnetonka and Minnehaha Creek.

MCWD's real-time sensor network and partnership with HCEM and USGS is featured as a "Community Highlight" on page 39 of the recently adopted 2020 State Water Plan: Water and Climate prepared by the Environmental Quality Board. 

Water Level Resources
Copyright © 2022 Minnehaha Creek Watershed District, All rights reserved.


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