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Water Levels Update

(Updated Wednesday, July 17)

Flash Flood Watch map

July 15 - July 16 Rainfall Summary & Potential for Localized Flooding July 17 - 18


Flash Flood Warning
The National Weather Service (NWS) has issued a flash flood watch from 7pm tonight, Wednesday, July 17 until 7am tomorrow, Thursday, July 18. They're predicting approximately 0.9 inches of rain tonight into Thursday with the chance for areas of heavy rain and flash flooding. The Twin Cities have a slight risk of excessive rainfall later this afternoon into this evening. Minnehaha Creek Watershed District (MCWD) is advising that there is a chance for localized flooding across the watershed.

Following this rainfall, the NWS is predicting dry weather in the watershed for the next week. Assuming we receive around one inch of rain tonight and the seven day forecast stays relatively dry, MCWD anticipates that it will take approximately two weeks before water levels across the watershed will start to see some relief.

Watershed rainfall totalsJuly 15 - 16 Rainfall Summary
Rainfall totals on July 15 were higher than anticipated in some areas and according to the Hennepin County Mesonet weather stations, totaled between approximately 0.63 - 2.37 inches across the watershed (see map to right).

Yesterday, July 16, a very local storm quickly dropped 1.5 - 2.5 inches near Hopkins and St. Louis Park. The areas shown in red in the linked map received over two inches of rain in one hour.

June 2019 Hydrologic Conditions Report
The MN Department of Natural Resources (DNR) released the June 2019 Hydrologic Conditions Report today. It identified that:

  • Water levels were above average on 73% of gauged lakes across the state
    • On 63% of these “above average” lakes, water levels were six inches above average
  • Groundwater levels for submitted sites were above average to high throughout a large part of southern Minnesota
    • 7 groundwater sites recorded their highest water levels for the period, including one site with a 45-year record high

4th Wettest Start to a Year
The 1.75-inch rainfall at the MSP Airport on Monday, July 15 pushed the Twin Cities to the 4th wettest year to date since record keeping began in 1871. As of July 16, 23.32 inches of precipitation has fallen in 2019, which is 7.43 inches above normal.

Year to Date precipitation graph

Total precipitation top ten table

Metric 2013 2019 Difference
May 3 Lake Minnetonka Elevation 928.75 ft 929.85 ft Lake Minnetonka 13.2 inches higher in 2019
Jan. 1 – July 15 Total Precipitation 24.02 inches 23.31 inches 0.71 inches more in 2013
July 15 Lake Minnetonka Elevation 930.15 ft 929.57 ft

Lake Minnetonka 6.72 inches lower in 2019

 

The table shows that in spite of starting 2019 higher than in 2013, and with nearly equal precipitation Jan. 1 – July 15 during both years, Lake Minnetonka’s water level is nearly 7 inches lower than it was in 2013 at this time.
 
This means the MCWD was better able to manage Gray’s Bay Dam in 2019 and reduce Lake Minnetonka’s water level overall despite the record rainy weather.

This is a great example on how MCWD’s partnership with NWS, U.S. Geological Survey (USGS), and Hennepin County Emergency Management (HCEM) has resulted in less flooding and better management of the water budget across all 178 square miles of our watershed.

Lake Minnetonka Water Levels GraphLake Minnetonka and Gray's Bay Dam

  • The July 15 - 16 rain event caused Lake Minnetonka’s lake level to increase 0.72 inches to an elevation of 929.63 feet above sea level (see graph below). While this is 2.76 inches above the ordinary high water level of 929.40 feet, it is 4.44 inches below the emergency spillway
  • We anticipate the rain predicted for tonight and tomorrow will increase the lake level to approximately 929.70 feet above sea level
  • It is likely that Lake Minnetonka’s water level will remain at approximately 929.70 feet for the next few days as upper watershed streams continue to drain into the lake
  • Due to the relatively dry and hot weather over the past week, Lake Minnetonka dropped below 929.60 feet on July 15 which is in "Zone 4" of the Gray’ Bay Dam operating plan (see graph below). That allowed us to reduce the discharge to a maximum of 150 cubic feet per second (cfs), providing some relief to downstream communities
  • The rain on July 15 - 16 caused a small increase in the lake level, however the Gray’s Bay Dam continues to discharge 150 cfs to create storage in Minnehaha Creek, which is currently flowing bank full

Gray's Bay Dam discharge zones graphMinnehaha Creek

  • Since its peak on July 2, Minnehaha Creek flow had fallen almost 200 cfs over the past couple of weeks due to the dry weather
  • During the July 15 - 16 rain events, Minnehaha Creek peaked at 443 cfs at 7:40pm on July 15 and 443 cfs at 12:20am on July 16
  • Minnehaha Creek is currently flowing bank full around 290 cfs near Hiawatha Avenue in Minneapolis
  • High flows are expected to continue on the creek due to this week's rain and as water from across the watershed continues to drain into Minnehaha Creek
  • MCWD is advising people that it is unsafe to paddle the creek at this time. Ideal creek flow for paddling is between 75 - 150 cfs. Flows above 150 cfs can make it difficult to react to obstacles (downed trees, branches, etc) in the creek and to pass under some bridges. There are a lot of obstacles in the creek, as city crews have not yet been able to remove them due to high water. Learn more about paddling conditions

Lake Nokomis (Minneapolis)

  • Today's Lake Nokomis’ water level reading is 816.03 feet above sea level, which is 7.56 inches above the ordinary high level of 815.40 feet
  • The stretch of dry weather allowed the weir at Lake Nokomis to be opened on July 9 to relieve high water conditions and helped drop the lake level almost one foot before the weir was closed on July 15 ahead of this week's rain
  • The Nokomis weir was closed by the Minneapolis Park and Recreation Board (MPRB) on July 15 to prevent peak Minnehaha Creek flows from entering the lake. MPRB plans to reopen the weir after the predicted rain this week, once Minnehaha Creek flow stabilizes and falls below the lake outlet
  • MPRB and MCWD staff will continue to look for opportunities to open the weir to allow the lake to drain into Minnehaha Creek while still protecting the lake from inflows from the creek

Lake Hiawatha (Minneapolis)

  • Today's Lake Hiawatha level reading was 814.66 feet above sea level, which is approximately 1.86 feet above the ordinary high water level of 812.8 feet
  • The current lake level is approximately 1.04 feet below the berm that separates Lake Hiawatha from the Hiawatha Golf Course

Mooney Lake (Plymouth)

  • Yesterday's (July 16) Mooney Lake reading was 990.45 feet above sea level, which is approximately 2.45 feet above the ordinary high water level of 988 feet
  • The Mooney Lake emergency pump is turned on whenever the lake level reaches the elevation of 990 feet between March – September and will remain on until the lake falls below 989 feet
  • MCWD in coordination with the City of Plymouth and the City of Wayzata collectively determined that all the necessary parameters had been met and the emergency pumps were turned on April 19 and continue to operate
  • During the pumping, MCWD will monitor downstream water bodies to see if any high water conditions exist  

Record Setting Precipitation

The spring of 2019 was exceptionally wet which continued a record setting wet trend that started in 2013. The MN Department of Natural Resources (DNR) State Climatology office has observed that 2013 - 2018 finished as the wettest six-year period on record since record keeping began in the 1870s. During those six years an extra year’s worth of precipitation fell (~30 inches), meaning we have received seven years’ worth of rain in a six-year period.

The start of 2019 continued this wet trend not only across Minnesota but across the entire contiguous United States. The Twin Cities experienced the fourth wettest start to a year on record (Jan. 1 – July 15) with 23.32 inches of precipitation. As of July 17, this has resulted in the Twin Cities being 7.43 inches above average in precipitation for the year:

The 2019 spring flooding resulted in over $32 million in estimated damages to public property and infrastructure across 50 counties and four tribal nations across the State of Minnesota.

MCWD's Effort to Reduce Flooding

This winter was unique. We experienced a wet fall and the ground froze to a deep depth while soils were still saturated. Additionally, the amount of snow we received held 2.5 - 4.5 inches of water content, much of which melted quickly due to early March rains. MCWD is trying to balance the water budget across our entire 178 square miles and is working hard to reduce and prevent flooding. The balancing act this spring has been one of diligent timing:

  • With assistance from creek communities and MPRB, MCWD tracked and responded to ice jams along Minnehaha Creek to prevent flooding
  • MCWD got the Gray’s Bay dam operational while over 4-feet of ice surrounded the dam structure
  • On March 21, 2019 (one month before ice-out) MCWD began discharging water at the Gray’s Bay dam as soon as the risk of ice jams along Minnehaha Creek had diminished
  • MCWD has gradually increased the discharge at the Gray’s Bay dam as soon as Minnehaha Creek started to gain additional capacity  
  • MCWD is now trying to balance forecasted precipitation and its impacts on water levels and making adjustments when we can
  • Significant winter snowpack (11th snowiest season on record), deep frost, increased soil moisture, quick spring thaw, and the above average precipitation this spring have caused high water levels across the state of Minnesota

Looking Ahead and Coordination with Agency Experts

The seven day forecast from the National Weather Service shows dry weather, and the two-week outlook calls for below average precipitation.

Since March, MCWD has been actively coordinating with staff from the National Weather Service, U.S. Geological Survey, and Hennepin County Emergency Management to understand spring flooding predictions, water content of snow, current stream flows, and emergency coordination efforts. Prior to snowmelt, MCWD ran several hydrologic snowmelt modeling scenarios to identify the locations that could face potential spring flood risk. We coordinated the results of this modeling, as well as modeling for the upcoming rain event, with all 29 communities in the MCWD.
 
MCWD will continue to coordinate daily with agency partners, National Weather Service, U.S. Geological Survey, and Hennepin County Emergency Management to consult and review data to help inform Gray's Bay Dam operations.

The National Weather Service provides MCWD with seven-day precipitation forecasts and a prediction for how that precipitation will affect water levels. With this information, we can proactively create storage for the forecasted precipitation. Dam discharge can then be reduced before rainstorms and that storage is used to prevent flooding on Minnehaha Creek. MCWD also uses real-time weather data provided by Hennepin West Mesonet weather stations installed on MCWD properties and real-time water level data from the U.S. Geological Survey gauges on Lake Minnetonka and Minnehaha Creek.

Tips for Property Owners

Get the latest information by visiting our website and signing up for email updates.

Review your insurance coverage. There is a 30-day waiting period before a flood insurance policy takes effect. Learn more about flood insurance. Check to see if your policy covers sanitary sewer back-ups. More information is available from the Insurance Information Institute. Other resources include:

For specific questions about local flood response, including where to find sand bags and other resources, contact your city.

Minnehaha Creek

  • Edina – Dave Goergen, Public Works Coordinator, 952-826-0312
  • Hopkins - Hopkins Public Works, 952-939-1382
  • Minneapolis - 311 or 612-673-3000
  • Minnetonka – Minnetonka Public Works, 952-988-8400 between 7am-3:30pm
  • St. Louis Park – Steve Koering, Fire Chief, 612-790-4019

Lake Minnetonka

  • Deephaven – Dana Young, City Administrator, 952-358-9939
  • Excelsior - Tim Amundsen, Public Works Superintendent, 952-653-3676
  • Greenwood - Dana Young, City Clerk, 952-358-9939
  • Orono – 952-249-4600, after hours call Dispatch at 952-258-5321
  • Wayzata – Mike Kelly, City Engineer/Director of Public Works, 952-404-5316

Water Level Resources