September 9-12 Rainfall Summary & Water Levels Update

Rainfall totals between September 9-12 totaled on average between approximately 2.5 - 3.3 inches according to the Hennepin County Mesonet weather stations (see map below). This brings the Twin Cities’ total precipitation this year to 34.22, which is 10.75 inches above normal.

2019 Remains Second Wettest Year to Date on Record

2019 continues to rank as the second wettest year to date (since record keeping began in 1871) with 34.22 inches of rain falling between Jan. 1 – Sept. 12. For comparison, in a normal year the Twin Cities receives approximately 30.61 inches of precipitation total (from Jan. 1 - Dec. 31). With 34.22 inches of rain thus far in 2019, we have received more rain than the entire calendar year (Jan. 1 - Dec. 31) in 2017 (32.36 inches) and 2018 (33.57 inches).  
 

Lake Minnetonka & Gray's Bay Dam

• The Sept. 9-12  rain event caused Lake Minnetonka’s water level to increase 3.72 inches to an elevation of 929.47 feet above sea level (see graph below), which is 0.84 inches above the ordinary high water level of 929.40

• After the rain stopped on Thursday, the dam discharge was increased to 150 cubic feet per second (cfs) to mitigate the inflows coming into Lake Minnetonka from the upper watershed streams
• This rain has caused the dam operations to move to "Zone 3" which is noted as the orange color in the dam operating plan graphic below
  • Zone 3 of the dam operating plan requires a minimum discharge of 150 cfs

Minnehaha Creek

• On Monday, Sept. 9, the dam discharge was reduced to 50 cfs to create storage capacity in Minnehaha Creek for the upcoming rain
• This reduction in dam discharge helped to reduce the peak Minnehaha Creel flow despite over 2.5 inches of rain falling
• Minnehaha Creek flow peaked at 354 cfs at 12:15pm on September 12
• Since the rain stopped, Minnehaha Creek’s flow has been steadily dropping and is currently flowing around 225 cfs
• 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 some obstacles in the creek, as city crews are working to remove them as they are able. Learn more about paddling conditions

Minneapolis Lakes

• Powderhorn Lake is currently at 820.3 feet above sea level which is approximately 1-foot of above the banks of the shoreline
• The dock and pathway are not accessible
• Due to Powderhorn Lake being a landlocked basin, water is pumped out of the lake and directed to the Mississippi River to reduce high water levels
  • MPRB has applied to amend the DNR Water Appropriation Permit due to the current pumping allotment already being used in 2019

• Yesterday's Lake Hiawatha level reading was 814.54 feet above sea level, which is approximately 1.74 feet above the ordinary high water level of 812.8 feet
• The current lake level is approximately 1.16 feet below the berm that separates Lake Hiawatha from the Hiawatha Golf Course

• The Sept. 9-12 rain caused Lake Nokomis’ lake level to increase 5.76 inches to an elevation of 815.96 feet above sea level, which is 6.72 inches above the ordinary high water (OHW) level of 815.40
• The Minneapolis Park and Recreation Board (MPRB) closed the weir on Sept. 10 to prevent Minnehaha Creek from flowing into the lake
• MPRB staff will assess creek levels on Sunday, Sept. 15 and will either open the weir then or on Monday, Sept. 16

• Yesterday's Lake Harriet lake level reading was 848.86 feet above sea level, which is 10.32 inches above the ordinary high level of 848 feet

• Yesterday's Bde Make Ska lake level reading was approximately 854.78 feet above sea level, which is 1.78 feet above the ordinary high level of 853 feet

Hannan Lake (St. Louis Park)

• Hannan Lake is a landlocked basin in St. Louis Park and its high water levels are threatening to flood homes
• The City of St. Louis Park has applied for a DNR Water Appropriations Permit to temporary pump 3.5 million gallons to Cobble Crest Lake which then discharges into Minnehaha Creek 

Mooney Lake (Plymouth)

• Yesterday’s Mooney Lake reading was approximately 989.40 feet above sea level, which is approximately 1.4 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  

Mary Lake (Shorewood)

• Mary Lake's current elevation is approximately 955.5 feet above sea level, which is approximately 3.5 feet above its estimated ordinary high water level of 952 feet
• The City of Shorewood was issued a DNR Water Appropriations permit to temporary pump up to 4.5 million gallons of surface water from Mary Lake to lower the lake level to prevent flooding of homes
• The pumping of Mary Lake will stop when the water level of Lake Mary reaches 952 feet 
• The discharged water from Mary Lake is being pumped to Lake Linden which is being monitored for high water as well

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. 2019 continued this wet trend not only across Minnesota, but across the entire contiguous United States.

• The Twin Cities had the 2^nd wettest January 1 – August 18 on record
• The Twin Cities had the 8^th wettest spring on record (March 1 – May 28)
• The Twin Cities had the 11^th wettest May on record
  • Total May 2019 precipitation was 6.68 inches, which is 3.76 inches above average for the month
• The State of Minnesota had the 4^th wettest 12-month period on record (May 2018 - April 2019)
• The United States experienced the wettest 12-month period on record (May 2018 - April 2019)
• For the third consecutive time in 2019 (April, May, June) the United States experienced the wettest 12-month period on record (July 2018 – June 2018)

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.

Looking Ahead & Coordination with Agency Experts

The seven day forecast from the National Weather Service shows rain mid-next week 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.

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, 952-292-6225
• 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

• 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

• Track updates on Twitter by following @graysbaydam
• Current and historical lake levels and discharge rates can be viewed on our website
  • We recently added an "Explanation" column to provide insight into why the dam adjustment was made
• USGS automated lake level reading of Lake Minnetonka
• USGS automated flow and height reading of Minnehaha Creek at Hiawatha Ave