By Paige Kieffer
The Minnehaha Creek Watershed District has partnered with the U.S. Geological Survey to monitor water levels on Lake Minnetonka and the Minnehaha Creek.
The Minnehaha Creek Watershed District is celebrating its 50th anniversary this year. Gray’s Bay Dam in Wayzata was built in 1979 to help control flooding along the creek.
Telly Mamayek, the watershed district director of communications and education, said the watershed was founded in 1967 after Twin Cities’ residents along the creek created a petition to form a watershed. This was sparked by massive flooding that occurred during the spring of 1966, causing many neighborhoods to flood.
“Flood Prevention is why the Minnehaha Creek Watershed District was founded,” Mamayek said.
Laura Domyancich, watershed district project and land technician added, “This was actually the first project of the Minnehaha Creek Watershed District and we were asked to figure out a solution for flooding on the creek and how to maintain a lake level that was viable to the lake while also maintaining a level of flow through the creek.”
Domyancich controls the output of water from the dam by using hand-cranked wheels that she adjusts three times a week, sometimes more often if conditions warrant. She takes readings from gauges located on the both sides of the dam and then adjusts the amount of water discharged based on the readings.
“We have these gauges to understand where the lake and creek are at throughout the day and throughout the week,” Domyancich said.
The watershed district partnered with the U.S. Geological Survey this spring to add an automated measuring gauge at the dam. This new gauge and another at Hiawatha Avenue in Minneapolis, take flow level and the elevation measurements.
The recorded data can be viewed in real time at bit.ly/2riWvaG.
Domyancich said that having these measurements has assisted in controlling water levels to help prevent flooding.
The watershed district also partners with Hennepin County Emergency Management and the National Weather Service. All the organizations work together to track weather patterns to better predict what water levels will be on the lake and therefore allowing water flow onto Minnehaha Creek be better controlled.
The county emergency management has weather stations in Minnetrista and St. Bonifacious, where they provide the watershed district with real time data on humidity, temperatures, wind and other basic weather information. The weather information from the upper watershed creeks, including Painter’s Creek and Six Mile Creek, helps predict how Lake Minnetonka water levels will be affected by the water flowing into the lake from these streams.
“While weather can be very different throughout our 180 square miles, that gives us an opportunity to understand exactly understand how much water we’re getting in the upper watershed and how it will effect lake levels down the line,” said Domyancich.
The watershed district also has a partnership with the National Weather Service to receive weather data and precipitation predictions that assist with increasing lake discharge in advance of high precipitation and decreasing discharge shortly before the rain begins to provide capacity in Minnehaha Creek.
“It’s been huge benefit in the last couple of years,” Domyancich said. “This year we’ve had really rainy spring, and last year we had a really rainy fall, so with the National Weather Service’s precipitation predictions, we’ve been able to keep good levels.”
On June 16, after a few major storms, Lake Minnetonka’s water level was at 929.5 feet. According to the operating plan, when the lake is at that level during June, the watershed discharges water at a rate of 20-150 cubic feet per second. The current discharge is 150 cubic feet per second to provide some room in the lake for additional rainfall and runoff without overwhelming the creek during rain events.
“This is really a balancing act between the lake and the creek, so we want to protect both and we want to protect residents from property damage and we want to protect the resources also from damage from high waters,” said Mamayek. “It’s really controlling the water levels before and after rain. It’s one large system and the dam is the control mechanism that helps control and manage water levels on both sides.”
Domyancich said she also adjusts the dam and releases higher levels of discharge before a major storm event to create room in the lake for the additional rainfall. The precipitation that collects in Lake Minnetonka is slowly released during the days after a storm.
She said the lake has a spillway in Wayzata in case of unusual high water.
“We have essentially kept up with what has been coming into the lake, from precipitation through discharge, and without putting too much water out onto the creek and flooding it,” Domyancich said. “It’s been a balancing act the past few weeks that we’ve had a lot of rain but it has come in a metered way and we’ve been able to manage where the lake is at with discharge.”