Section 319
NDNPDINT SOURCE PROGRAM SOGGESS STORY
Nutrient Concentrations in the Minneapolis Chain of Lakes Nearly
Returned to Presettlement Conditions
Waterbody Improved
The Minneapolis Chain of Lakes, located two and a half miles south-
west of downtown Minneapolis, Minnesota, receives urban runoff
delivering high levels of phosphorus and sediment from its fully developed 7,000-acre watershed.
Through implementing a widespread public education campaign, sediment control measures, and other
practices throughout the watershed, the Minneapolis Chain of Lakes Clean Water Partnership achieved
significant in-stream reductions in sediment and phosphorus which has helped most of the lakes stay off
the state's 303(d) list and has also brought a listed stream close to meeting water quality standards.
Problem
The Minneapolis Chain of Lakes is the most
visited natural resource in Minnesota, drawing
more than 5.5 million visitors annually. Decades
of intense recreational use and urban develop-
ment was degrading water quality, contributing
to algae blooms, and impacting recreational acti-
vities on the lakes. An extensive watershed and
lake monitoring program identified total phos-
phorus and sediment as the pollutants of con-
cern. Using innovative techniques to estimate
the historical water quality of the lakes (based
on readings of sediment cores), lake managers
were able to identify presettlement phospho-
rus concentrations at less than 20^/g/L, which
increased by the end of watershed development
in the 1970s to values in excess of
Project Highlights
In 1990 citizens and interested groups formed
the Minneapolis Chain of Lakes Clean Water
Partnership (CWP) and started one of the larg-
est urban lake restoration projects in the United
States. CWP established nutrient reduction goals
for each of the lakes in the chain, then set out to
accomplish these goals through $12.4 million of
rehabilitation actions. On-the-ground practices
were initiated in 1995 in the upper watershed
reaches above Cedar Lake and then progressed
down through the rest of the Chain of Lakes.
Project activities focused on constructing
sedimentation basins, wet detention ponds, and
created wetlands to drain urban stormwater and
intercept sediment and nutrient loads flowing
Brownie Lake
Twin Lakes
Cedar Lake
Minneapolis
Chain of Lakes
Lake of the Isles
Lake Colhoun
IP Grit Chambers
O Wetland and
Stormwater Ponds
Shoreline Restoration
Alum Treatments
Lake Sampling
Goose Removal
Lake Harriet
through the watershed. Projects included a
two-cell wet pond at Cedar Lake and a three-cell
sediment basin adjacent to Lake Calhoun. Other
efforts focused on extensive shoreline erosion
prevention measures from Cedar through Harriet
Lakes, followed by the installation of numerous
grit chambers, pocket wetlands, and improved
street-sweeping practices. Alum treatments
(using a nontoxic material to control internal
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recycling of phosphorus from sediments on the
lake bottom) were also implemented at Cedar
and Lake of the Isles in 1996 and 1997, and com-
pleted in Lake Calhoun and Lake Harriet in 2001
with the support of section 319 funding. Other
important measures included new regulatory
controls and stepped up enforcement efforts to
limit phosphorus in fertilizers.
A major education and awareness effort, begin-
ning in 1993 and continuing to present, was also
critical to the overall rehabilitation of the Chain
of Lakes. The CWP increased public awareness
through a marketing campaign that distributed
bookmarks, table tents and paper placemats for
restaurants, utility bill inserts, pet waste post-
ers, billboards, newspaper articles, and lawn
care mailings throughout the watershed.
Results
The education and awareness efforts target-
ing homeowner pesticide use appear to have
quickly paid off with measurements of over 50
percent reduction in pesticides observed in
stormwater runoff. Present efforts continue to
focus on lawn and pesticide users.
Measurable improvements in water quality have
also been documented throughout the Chain
of Lakes, successfully meeting or exceeding
CWP goals targeting presettlement phosphorus
concentrations of less than 20 ji/g/L. The larg-
est watershed changes occurred in the Lake
Calhoun watershed with average total phospho-
rus values in the 20-25 ^/g/L range (exceeding
the CWP goal for Lake Calhoun of 25 jL/g/L).
Measurable reductions also occurred in less
than 3-4 years for Cedar Lake, with phosphorus
concentration values decreasing from a range
of 40 to 75 jL/g/L to values of less than 30 ji/g/L.
These reductions have been accompanied by
reductions in chlorophyll a concentrations (from
averages in the 15 to 25 fig/L to about 5 ji/g/L),
and increased transparency from pretreatment
averages of 1 to 2 meters to values in excess of
2 to 3 meters. Lake Harriet, the furthest down-
stream lake with the best water quality when
the CWP started, also showed improvement,
meeting the project goal of 20 jjg/L—similar to
the presettlement condition.
Lake of the Isles—a shallow lake extensively
dredged over time—has not experienced as
great an improvement as the other lakes, and
in 2002 was placed on the state's 303(d) list
as impaired by nutrients. Phosphorus values
now appear to have stabilized in the 25-50 ji/g/L
range, slightly exceeding the targeted value of
40 jL/g/L for the Lake. A TMDL is currently under
development for Lake of the Isles that address-
es the unique challenges of this shallow lake.
Through this effort, project partners—includ-
ing the Minnesota Pollution Control Agency
(MPCA), Minnehaha Creek Watershed District
(MCWD), Minneapolis Park and Recreation
Board (MPRB), and the City of Minneapolis—
intend to establish goals that not only will result
in a delisting of Lake of the Isles, but will also
establish a policy for other shallow and urban
lakes facing similar challenges.
As a result of the comprehensive, pro-active
approach throughout the Minneapolis Chain of
Lakes, all of the lakes have achieved significant
reductions in sediment and phosphorus, helping
most of the lakes stay off of the state's 303(d)
list of impaired waters.
Partners and Funding
The Chain of Lakes Water Quality Management
Citizens Advisory Committee is composed of 34
members from neighborhoods, neighborhood
organizations, appointees, business owners, rec-
reational use groups, and environmental organi-
zations. The majority of the initiative was locally
funded by the MPRB ($1.5 million), MCWD
($6.1 million), City of Minneapolis ($2.6 million),
City of St. Louis Park ($663,000), and Hennepin
County. Critical diagnostic and seed money was
provided by the MPCA ($1.2 million). The U.S.
EPA section 319 funds totaled $255,000 and
were used to fund kick-off efforts for the educa-
tion campaign, a demonstration project on Lake
Calhoun showing the effects of alum treatments,
and research on the interaction between alum
and milfoil (an invasive species).
I
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« U.S. Environmental Protection Agency
\ Off ice of Water
o Washington, DC
/
EPA841-F-05-004W
September 2005
For additional information contact:
Sara Aplikowski
Minneapolis Park and Recreation Board
612-313-7782 • saplikowski@minneapolisparks.org
Jim Hafner
Minnehaha Creek Watershed District
952-471-0590, x202 • jhafner@minnehahacreek.org
Bruce Wilson
Minnesota Pollution Control Agency
651-282-2619 • bruce.wilson@pca.state.mn.us
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