For the past several years, residents in the Nokomis area of
Minneapolis have expressed concerns over rising groundwater levels and higher water
levels in Lake Nokomis. Their concerns
include impacts to sewer infrastructure and standing water in previously dry
areas near Solomon and Nokomis Parks.
To respond to these concerns, the city of Minneapolis launched
a partnership with the Minneapolis Park and Recreation Board, the Minnehaha Creek
Watershed District, Hennepin County and the Minnesota Department of Natural
Resources. The group has committed significant resources, including the time
and expertise of more than 30 staff, toward better understanding what’s going
on with groundwater and surface water levels in the area, how they may be
interacting, what might be done to address problems, and how to keep
stakeholders informed. Actions taken to date include:
- Four observation wells have been installed at
Solomon Park and Nokomis Park to provide better information about groundwater
levels and movement in the area.
- Two deeper bedrock aquifer wells will be
installed in the near future. The six
wells together will provide additional information about groundwater levels and
movement in the area, including vertical movement of groundwater.
- An inter-agency technical team consisting of hydrologists,
geologists, planners, ecologists and engineers has met four times to analyze
existing data and identify needs for further information.
- Lake Nokomis water level data have been analyzed
in relation to what is known about the soils and geology in the area, as well
as in relation to the location of residential reports of groundwater issues
with sewer laterals or foundations.
- A project website has been set up, and an
inter-agency team has been established to coordinate communications and outreach
to the public.
- A preliminary overview of some of the drivers of
higher water levels has been gathered into a fact
sheet that is available on the project
website.
The biggest factor affecting water levels in and around Lake
Nokomis is something everyone loves to talk about, but no one knows how to fix:
the weather.
During most of this past August, for instance, the Twin
Cities metro area was listed as “Abnormally Dry” on the U.S. Drought Monitor.
That dry weather resulted in lower water levels in Minnehaha Creek and on Lake
Nokomis for several weeks. The lack of rain left Minnehaha Creek running on the
low side from July 26 through September 19. The water level on Lake Nokomis
also dropped below the weir’s outlet elevation of 815.10 feet sometime around
August 11, meaning water could no longer flow from Lake Nokomis to Minnehaha
Creek. It remained below the outlet through mid-September. Prior to 2018, the
last time the water level on Lake Nokomis dropped below the outlet elevation
was on November 28, 2017.
In 2018, due to dry weather, water flowed out of the lake via
the weir for only 53 days. In comparison, from mid-March to the end of December
2017, the weir was open for 121 days and water flowed out of the lake until it
dropped below the outlet elevation at the end of November.
Recent rainfall has prompted the reopening of the Lake
Nokomis weir. On September 25 the lake level measured 815.98 and water is once
again flowing out of the lake.
The weir is a dam-like structure that prevents polluted
stormwater and zebra mussels from entering Lake Nokomis from Minnehaha Creek. The
Minneapolis Park and Recreation Board operates the weir in coordination with
the Minnehaha Creek Watershed District consistent with an approved operating
plan. For more information, view the Lake Nokomis Outlet Operating Plan.
After video images showed significant deterioration in the
60-year-old concrete sanitary sewer pipe running along 14th Avenue
in Solomon Park, the city of Minneapolis hired a contractor this summer to
replace it. To minimize damage to trees in the park, the contractor used a
minimally invasive technique called “pipe bursting,” which uses a tool to break
up the old pipe underground while pulling new plastic pipe through behind it.
During construction, which ran from mid-August to mid-September, crews observed
a minimal amount of groundwater seeping into the three pipe-bursting pits. That
groundwater was pumped directly into the sanitary sewer. The new high-density plastic pipe running
from 58th Street to 59th Street is now in place and fully
functional.
As part of efforts to keep area residents informed and
engaged, the Nokomis Area Groundwater and Surface Water Evaluation team is
planning an open house on Wednesday, Oct. 24, from 6 to 8 p.m. at the Lynnhurst
Recreation Center, 1345 W. Minnehaha Pkwy, Minneapolis.
No formal presentations
are planned, but staff from the City of Minneapolis, the Minneapolis Parks and
Recreation Board, the Minnehaha Creek Watershed District, the Department of Natural
Resources and Hennepin County will be on hand to provide information and answer
questions on a variety of topics related to groundwater and surface water
issues in the area.
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To continue to receive updates on this issue, please sign up to receive email updates on the Nokomis Area Groundwater & Surface Water Evaluation Project. You can also visit the project website to learn more.
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