Minnehaha Creek to see TLC

Flood prevention work starts this fall

FEMA will repair or remove aging streambank walls along the creek. Photo courtesy of the Minnehaha Creek Watershed District
FEMA will repair or remove aging streambank walls along the creek. Photo courtesy of the Minnehaha Creek Watershed District

Minnehaha Creek is running high.

The year 2016 was the wettest on record. This spring set a record for all-time snowiest start to the calendar year. In both 2013 and 2014, water submerged the dam at Gray’s Bay in Lake Minnetonka that controls the flow of water down the creek.

Weather patterns that were once predictable, with a wet spring and a dry fall, are not the case in recent years — now it’s raining into December, said Tiffany Schaufler, senior project manager at the Minnehaha Creek Watershed District (MCWD).

“We just don’t get much relief,” she said. “We’re just having to deal with a lot more water than we used to.”

Mike McKinney fishes Minnehaha Creek in Tangletown.
Mike McKinney fishes Minnehaha Creek in Tangletown.

Minnehaha Creek will see an infusion this year of about $500,000 in funding from the Federal Emergency Management Agency to repair streambanks damaged by flooding, including four sites in Tangletown. Retaining walls built as part of the Depression-era Works Progress Administration (WPA) have been degrading over time, and flooding has further eroded slopes. Workers will repair bank erosion with riprap, reconstruct a channel to accommodate higher flows, stabilize banks, and repair or remove WPA walls.

 

During the June 2014 flood, the Gray’s Bay dam couldn’t control the water flow for 83 days. Residents reported water in their basements, and the city sent sandbags to Burroughs School.

A key change following that flood is a new partnership with the National Weather Service. The Weather Service now issues seven-day forecasts in six-hour increments, so the MCWD can use the dam to manage flooding. Ahead of major rainfall, they can release more water from the lake so the dam has capacity to properly store water.

“Especially in 2016, when it was the wettest year on record, we were actually able to manage the lake and the creek and not flood anybody,” Schaufler said. “That’s been a very huge step forward for dam management and trying to prevent flooding. … With climate change, we’re getting these big rain events more often.”

The big picture

The upcoming FEMA work dovetails with a long-term master planning process for the creek, which is just getting started. A master plan would be created essentially from scratch. There are Theodore Wirth’s original plans, which date back to the 20s and 30s, and there are updated plans that date back to the 60s and 70s, responsible for the separate pedestrian and bike trails and most of the pedestrian bridges across the creek.

Minnehaha 5

“This is the opportunity for a new vision,” said Adam Arvidson, director of strategic planning for the Minneapolis Park and Recreation Board.

The Metropolitan Council requires the Park Board to have a master plan in order to spend state and regional money on the creek.

One big question is what to do with all of the tennis courts along the creek. Arvidson said many are in disrepair. If stakeholders decide there are too many courts, discussions will begin on which ones should go and how the land should be used.

“I don’t propose at this point to know the answers to any of those questions,” Arvidson said.

He said community members will spend the next nine months providing feedback. He’s watching survey responses submitted at minneapolisparks.org. Many of the current responses are focused on pedestrian safety at busy intersections, he said.

The master plan will revive another question about whether to extend the paved trail from Lynnhurst Park to the Edina border.

“We will resolve that question as part of this,” Arvidson said.

A neighborhood survey in 2014 found that most of the 600 respondents wanted to leave the stretch of creek path natural, as it is. At the time, respondents said they wanted to shore up the creek and improve it environmentally.

Whenever it rains, stormwater enters the creek that’s polluted with road salt, dirt, leaves and grass clippings that add salt and phosphorous to the creek. The further downstream, the more polluted the creek is, according to the MCWD. The water quality at any given time varies based on recent rainfall, water volume and the speed of the flow from Lake Minnetonka.

“Anytime you’re draining a 27-square-mile urban watershed through a creek in South Minneapolis, you’re bound to not be pristine,” Arvidson said.

Managing street stormwater

The MCWD is working with the Park Board and the City of Minneapolis on a project to analyze the creek’s outfalls, or culverts.

“There’s over 100 culverts along the stretch of Minneapolis that drain all the streets into the creek,” Schaufler said. “That’s just a lot of water coming into the creek really quickly. You get a really big pulse of water, and the creek just jumping.”

Minnehaha 4

The MCWD has identified about a dozen concrete culverts to potentially pull out entirely. The project would shift creek banks there to raingardens or underground storage so that water could be cleaned and slowly released into the creek. The final locations will be chosen as part of the master planning process with public feedback.

For more information on the master plan, visit minneapolisparks.org.

For more information on the upcoming FEMA work, visit minnehahacreek.org.

Browse

More in Focus Neighborhood Spotlight