EPA/600/F19/043
oEPA
w w w. epa. gov/resea rc h
technical BRIEF
INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE
Ecosystem Services
Analysis for Habitat
Restoration Alternatives
at Mud Lake on the St.
Louis River, Minnesota
The purpose of this analysis was to
compare the ecosystem services
associated with each of the six
different alternatives selected by
the City of Duluth, Minnesota, for
the restoration of habitat at Mud
Lake on the St. Louis River.
Specifically, the alternatives were
analyzed to map indicators related
to ecosystem services at Mud Lake
(i.e., the service providing areas) and
to estimate the area or extent
associated with each service. The
ecosystem service metrics were
either suggested by local
stakeholders or were based on
metrics described by Angradi et al.
(2016; Table 1). The area or extent
of each service was then tabulated
for each alternative (Table2).
Ecosystem services analyzed for
Mud Lake included both supporting
and final ecosystem services.
Supporting services provide an
indirect human benefit such as fish
habitat or wetlands; final services
are outputs of nature that provide a
direct benefit such as fish or wild
rice (Boyd and Banzhaf 2007). The
final services provided by Mud Lake
benefit a variety of people, including
recreational, subsistence, and
commercial beneficiaries.
Supporting ecosystem services
The analysis shows that there are
service trade-offs among (Table 2).
Alternative 3 (remove causeway)
provides the greatest opportunity
for increasing deep water habitat
and restoring connectivity between
the east and west sides of Mud Lake.
Deep water habitat that does not
freeze to the bottom or become
hypoxic during winter is important
for fish overwintering in the river.
Hydrologic connectivity is important
to maintain coastal wetland
vegetation communities, and their
associated fauna (Albert et al. 2005).
Because they increase connectivity,
Alternatives 2Av2 and 2Bv2 provide
the greatest opportunity for
providing coastal wetland sheltered
habitat, which is important for a
wide diversity of wildlife and fish
species (Niemi et al. 2007).
Alternatives 2A and 2B provide
slightly more area of dense
submerged aquatic vegetation
(SAV), though the absolute
difference in area among
alternatives is small (ca. 11 acres).
Areas with dense SAV are favored
as nursery habitat for many fish
species and provide food and cover
for a variety offish and wildlife
(Cvetkovic and Chow-Fraser 2011).
The current condition (i.e., keeping
Mud Lake as is) has the least
supporting service providing area
among the alternative analyzed.
Final ecosystem services
As with supporting ecosystem
services, trade-off among
alternatives was apparent for final
ecosystem services (Table2). For
both power and human-powered
boating, Alternative 3 provided the
greatest area because removal of
the causeway and the creation of
the northern channel allowed for
the greatest boatable area. It also
provided, along with Alternative 2B
and 2Bv2, the most area for shore
fishing due to the number of
designated shore-based fishing
areas included in this alternative.
Alternatives 2A and 2B provided
the greatest amount of Northern
Pike and Muskellunge (Esocid
fishes) spawning habitat owing to
the extensive shallow, moderately-
vegetated habitat preferred by
these fish for spawning, created by
these alternatives. However, it
should be noted that the absolute
difference among alternatives (ca.
10 acres) for this service is small
relative to the project area.
Alternative 3 (current conditions)
provides the least habitat area for
semi-aquatic mammals because
removing the causeway decreases
the length of riparian shoreline
available. Again, it should be noted
that the absolute difference in
shoreline area (ca. 15 acres) is
small relative to the project area.

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Limitations
A hydrodynamic model of current
velocities and wetland water
residence time was not available to
include in the analysis of the
various alternatives. All aquatic
vegetation models assumed that
current velocity will be like
conditions in other sheltered bays
in the river, such that
establishment of vegetation is
likely. Low current velocity could
promote aggradation of wetlands,
whereas high water velocity could
scour existing wetland habitat.
Also, upland vegetation plans were
not included with the alternatives.
Whether the adjacent riparian
corridor includes shrubs or mature
upland trees will influence
availability of habitat for wildlife,
waterfowl, and migratory birds. All
models were based on a water
elevation of 601.1 ft, and therefore
habitat values do not reflect high
water conditions (ca. 603 ft) or low
water conditions (ca. 599 ft).
Summary
The largest differences among the
Mud Lake restoration alternatives
are for overwinter fish habitat
(highest for Alternative 3 because it
includes the most open water
dredging) and boating and fishing
(also highest for Alternative 3
because the amount of aquatic
habit is increased by causeway
removal). On the other hand, the
amount of sheltered bay habitat,
shoreline, and floating leaved
vegetation is lower for Alternative
3 than for the other alternatives.
This analysis is based on area or
extent of services and all the
services are assumed here to have
equal per area benefit quality or
"value." The true relative value of
the different services (e.g., fishing
vs. wetland habitat vs. wildlife) will
likely vary among human
beneficiaries.
Without reliable estimates of
relative valuation for each service,
it may be useful to consider the
scarcity of the relevant Mud Lake
habitats in the context of the entire
St. Louis River Estuary ecosystem.
References
Albert, D.A., D.A. Wilcox, J. Ingram,
T.A. Thomson (2005)
Hydrogeomorphic classification for
Great Lakes coastal wetlands. J.
Great Lakes Res. 31 (SI): 129-146.
Angradi, T.R., Pearson, M.S.,
Bolgrien, D.W., Bellinger, B.J.,
Starry, M.A. and Reschke, C., 2013.
Predicting submerged aquatic
vegetation cover and occurrence in
a Lake Superior estuary. J. Great
Lakes Res., 39, 536-546.
Angradi, T.R. (2014) A predictive
model for floating leaf vegetation
in the St. Louis River Estuary. EPA
report for Minnesota Pollution
Control Agency. 16p.
Angradi, T.R., D.W. Bolgrien, J.L
Launspach, B.J. Bellinger, M.A.
Starry, J.C. Hoffman, M.E. Sierszen,
A.S. Trebitz, T.P. Hollenhorst.
(2016) Mapping ecosystem services
of a Great Lakes estuary can
support local decision-making. J.
Great Lakes Res 42:717-727.
Boyd, J., S. Banzhaf (2007) What
are ecosystem services? The need
for standardized environmental
accounting units. Ecol. Econ.
63:616-626.
Cvetkovik, M., P. Chow-Fraser
(2011) Use of ecological indicators
to assess the quality of Great Lakes
coastal wetlands. Ecol. Indie.
11:1609-1622.
Niemi, G.J., J.R. Kelly, N.P. Danz
(2007) Environmental Indicators for
the coastal region of the North
American Great Lakes: introduction
and prospectus. J. Great Lakes Res.
33(S 13): 1—12.
Contacts
Joel Hoffman, US EPA Mid-
Continent Ecology Division, 6201
Congdon Blvd, Duluth, MN 55803
hoffman.ioel(a>epa.gov
Ted Angradi, US EPA Mid-Continent
Ecology Division, 6201 Congdon
Blvd, Duluth, MN 55803
angradi.theodorePepa.gov
2
U.S. Environmental Protection Agency
Office of Research and Development

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Table 1. Ecosystem services analyzed for Mud Lake, including beneficiaries, associated subcategories, and ecosystem service source
Ecosystem Service (units)
Beneficiary
Subcategories
Description
Source
River greater than 6 feet
deep (acres)
Indirect
(Habitat)
Off-channel deep habitat
Potential for overwintering fish habitat
Suggested by
stakeholders
Highly-sheltered bay
(acres)
Indirect
(Habitat)
Back bay habitat
Relative amount of highly-sheltered aquatic
habitat relative to reference bays*
Angradi et al. 2016
Moderately-sheltered bay
(acres)
Indirect
(Habitat)
Back bay habitat
Relative amount of moderately-sheltered aquatic
habitat relative to reference bays*
Angradi et al. 2016
Fill in public waters (lineal
feet)
Indirect
(Habitat)
Loss of connectivity
Distance of artificial structures within project
area
Suggested by
stakeholders
Protected shoreline (feet)
Indirect
(Habitat)
Loss of connectivity
Distance of protected (rip rap) within project
area
Suggested by
stakeholders
75-100 percent
probability of vegetation
occurrence (acres)
Indirect
(Habitat)
Submerged aquatic vegetation
(SAV)
Area with dense SAV (e.g., eelgrass, coontail)
cover based on predictive models
Angradi et al. 2013
25-75 percent probability
of vegetation occurrence
(acres)
Indirect
(Habitat)
Submerged aquatic vegetation
(SAV)
Area with moderate SAV cover based on
predictive models
Angradi et al. 2013
50-100 percent
probability of vegetation
occurrence (acres)
Indirect
(Habitat)
Floating leaf vegetation (FLV)
Area with moderate to dense FLV vegetation
cover based on predictive models
Angradi 2014
Power boating (acres)
Recreational
Boaters, Anglers, Experiencers
and Viewers
Area of a suitable depth for power boating
(motorized)
Angradi et al. 2016
Human-power boating
(acres)
Recreational
Boaters, Anglers, Experiencers
and Viewers
Area of a suitable depth for canoes and kayaks
Angradi et al. 2016
Esocid spawning (acres)
Recreational,
Subsistence
Anglers
Area of habitat suitable for Northern Pike and
Muskellunge spawning
Angradi et al. 2016
Designated shore fishing
(acres)
Recreational,
Subsistence
Anglers, Food extractors, Food
subsisters
Area designated and suitable for shore-fishing
Angradi et al. 2016
Boat/ice fishing (acres)
Recreational,
Subsistence
Anglers, Food extractors, Food
subsisters
Area of a depth suitable for ice- or boat-based
fishing+
Angradi et al. 2016
Trapping (acres)
Recreational,
Commercial
Hunters, Pelt Extractors
Area of habitat suitable for semi-aquatic
mammals (e.g., river otters, beavers)
Angradi et al. 2016
* Sheltered bay morphology is based on the relative exposure index (REI) and is measured as the number of acres below the mean relative exposure index (Angradi et al. 2016)
for reference bays including Duck Hunter Bay, Radio Tower Bay, Stryker Bay, and Rask Bay.
+ Dependent on accessibility of western Mud Lake
3
U.S. Environmental Protection Agency
Office of Research and Development

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Table 2. Ecosystem services providing areas and extent for Mud Lake. The cells are color coded to help indicate relative change from current
condition among alternatives: yellow = less than a 30% change from current conditions; blue = at least a 30% increase in area or extent from
current conditions; pink = at least a 30% decrease from current conditions. For fill, a decrease in length is a positive change because it increases
aquatic habitat connectivity. A decrease in protected shoreline increases connectivity but decreases shoreline habitat.
Ecosystem Service (units)
Cu rrent
Condition
(Alt 1)
Retain Rail,
North Opening
(Alt 2A)
Rail to Trail,
North Opening
(Alt 2B)
Retain Rail,
North Opening,
Bay Mouth Bar
(Alt 2Av2)
Rail to Trail,
North Opening,
Bay Mouth Bar
(Alt 2Bv2)
Remove
Causeway,
North Opening,
Bay Mouth Bar
(Alt 3)
River greater than 6 feet deep (acres)
33.2
37.1
37.1
36.5
36.5
51.1
Highly-sheltered bay (acres)
23.4
26.5
26.5
30.9
30.9
9.8
Moderately-sheltered bay (acres)
29.8
28.2
28.2
42.6
42.6
21.0
Fill in public waters (lineal feet)
4894
4782
4782
4782
4782
3067
Protected shoreline (lineal feet)
4379
4107
4107
4107
4107
1302
75-100 percent probability of SAV
occurrence (acres)
75.9
84.3
84.3
79.3
79.3
73.3
25-75 percent probability of SAV
occurrence (acres)
42.7
40.5
40.5
40.4
40.4
46.2
50-100 percent probability (acres) of
FLV occurrence (acres)
42.2
51.2
51.2
57.9
57.9
2.9
Power boating (acres)
75.9
75.9
75.9
75.9
75.9
110.9
Human-power boating (acres)
129.7
129.7
173.4
129.7
173.4
184.0
Esocid spawning (acres)
75.7
84.0
84.0
78.9
78.9
72.9
Designated shore fishing (acres)
0.0
0.0
1.0
0.0
1.0
1.2
Boat/ice fishing (acres)
144.6
153.5
153.5
149.2
149.2
160.6
Trapping (acres)
133.6
124.7
124.7
128.2
128.2
118.7
U.S. Environmental Protection Agency
Office of Research and Development

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