Effects of Urbanization on the Mississippi
Caroline Karanja and Beverly Skulratana
Macalester College – St. Paul, MN
Urbanization along the Mississippi has been
detrimental to the areas freshwater system. Some of its
negative effects include an increase in storm water
runoff, water and air pollution and changing chemical
composition.
Stormwater Runoff
Possible Solutions
An important strategy deals with improving the quality and
quantity of stormwater runoff because all of the sediments end
up in the freshwater ecosystems altering everything from
biodiversity to temperature. Another important strategy is to
tackle air quality. This is often done through management and
initiatives taken by individuals, non-profits, and government
interference.
On an individual level, one manages runoff, by mowing less,
planting native vegetation, by not littering, and collecting
rainwater to be used for alternate uses. In terms of air quality,
one should find environmentally means of transportation. On
an institutional level, initiatives that stress management,
regulation, redevelopment of industry, housing, and transit,
sewage management, and conservation should be
incorporated. This is done through partnerships with energy
and conservation groups. This is done through the issue of
ordinances and planning that invest in alternate forms that are
beneficial to both the environment and its inhabitants.
Stormwater runoff often contains oils, chemicals,
phosphorous, nitrogen and toxic metals that are harmful
to freshwater organisms. The first sewer system in
Minneapolis, which drained sewage and stormwater
runoff into the Mississippi River, was built in 1870. In
1938, the Twin Cities built a separate sewage plant to
treat the water. However, as development continued, the
existing stromwater and sewage system could not
sustain the cities and would often over flood after heavy
rains. Better management of the cities sewage and
stormwater system began soon after. Still, as the Twin
Cities continue to expand today, the building of bigger
houses, building, parking spaces etc, one must consider
the effects this has on the Mississippi since there is a
direct correlation between stormwater runoff and
impervious surfaces. The debris and sediments found
the Twin Cities streets eventually heads into the river.
Water Pollution
Most of these pollutants in the Upper Mississippi River system result from urbanization and
agriculture. They impact the ecosystem, changing the plankton composition and production,
enhancing algal blooms, affecting the suitability of habitat for fisheries, and that of waters for human
use and consumption.
In Minnesota a lot of effort has been put to decrease point sources pollution. However, "non-point
sources" continue to harm the state's freshwater systems. Some come as a result of the
modification of the Upper Mississippi which have altered the distribution of sediments. The
modification of the Upper Mississippi has altered the distribution of the sediments. Sedimentation
has a dramatic effect on the ecosystem. Suspended sediments decrease light penetration, alter
habitat for organisms that require freshwater and in some cases, clog respiratory systems. Bedded
sediments bury some organisms or in large amounts, can bury eggs. The Twin Cities urban area
contains one of the nation's highest concentration of Chloride, about 1000-1850 milligrams per liter.
Most of this is a result of de-icing chemicals (Sodium Chloride) applied during winter that then runoff
the the cities' freshwater systems. These chemicals can then be easily disposed into wetlands or
near by streams. Studies show there is a direct correlation between the concentration of Chloride
and urban impervious spaces.