Extensive turbidity plumes at Long Beach area,
Standish, due to soil erosion caused by high lake levels at Sebago Lake.
Photo taken summer, 1998.
13. Analysis of lake-level management to invasive species threats
on Sebago Lake.
FOSL requests the EIS analyze the relationship between present lake level
management and the increased potential for the spread of invasive species.
Current literature suggests that water level regulation alters the variability
and habitat disturbances of a natural lake level regime. This alteration
can encourage the growth of invasive species. Much government funding has
been directed toward preventing the introduction of Eurasian milfoil and
halting the spread of variable leaf milfoil in Sebago Lake. Any increased
proliferation of milfoil and other nuisance weeds will harm recreation,
degrade water quality and devalue properties. This would be a great adverse
impact for the Sebago Lake environment and economy. Erosion of shorelines
and reduction of the the range of water level has allowed sandy substratum
to be covered by silt substrate coated with organic matter. This condition
is more conducive for the growth of invasive and nuisance plant species
than a natural sandy substrate. Scientific literature suggests that lower
winter or summer water levels can be useful in controlling Eurasian milfoil.
(Washington State Department of Ecology at www.ecy.wa.gov/programs/wq/plants/weeds/aqua004.html
)
Although Eurasian milfoil prefers mesotrophic lakes it does grow in very
oligotrophic lakes like Lake Chelan, Washington. Invasive plants like milfoil
prefer lake bottoms covered with silty, organic material. The FERC EIS should
analyze the changes of the lake bottom from a sand to silt and organic matter
caused by an increase in the mean water level and a reduction in the lake's
historic fluctuations.
From USA EPA: http://www.epa.gov/solec/96/coastal/stressors_of_glcw.html
" 4.2.8 Non-native Species
Species not native to the area, and aggressive species of uncertain origin
that compete with native biota, are serious biological stressors affecting
wetlands of the Great Lakes. Mills et al. (1993) documented the establishment
of 139 non-indigenous aquatic organisms in
the Great Lakes; many of which do not naturally occur in wetlands and do
not cause identifiable problems. However, several of these organisms do
cause or have the potential to cause considerable problems. The species
are found in coastal wetlands as a result of intentional release, deposition
from ship ballast, escape from cultivated or cultured populations, and migration
along travel routes such as railroads, highways, and canals. In healthy
ecosystems, introductions of non-native species may not be successful. However,
given the extent of wetland alteration in the Great Lakes, habitats and
food webs have been sufficiently disturbed to allow many introduced species
to thrive (Wilcox, 1995)."
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