Urban storm water runoff contains heavy metals including lead, organics such as pesticides, and nutrients like nitrogen and phosphorus in threatening concentrations which cause water quality problems in the receiving water bodies.
We are participating with adjoining cities and communities across the country to clean up storm water and reduce flooding. This will improve our public waters for recreational and environmental uses.
As part of the national storm water program, urbanized areas are in the midst of a second 5-year permit. The goal of the permit requirements is to reduce the harmful effects of storm water runoff and its potential to affect the quality of our public waters.
When it Rains, It Drains
Compared to natural areas, urban settings have a significantly higher percentage of impervious surfaces. Rooftops, sidewalks, parking lots, and streets create an impervious network that prevents storm water from infiltrating into the soil.
Water flows rapidly through this network and into storm sewers, which discharge directly into our lakes and streams. Unlike sanitary sewers, storm water is usually not treated (unless environmentally sensitive elements like detention ponds or bio-filters are utilized in the design).
The storm water enters our waterways carrying pollutants like oil drippings, pet waste, lawn fertilizers, and excess organic matter and sediment. But leaves and grass clippings are natural, right? Yes. But impervious roofs and pavements are not and they deliver the organics to our waters in unnatural volumes. The decaying vegetation releases carbon dioxide and uses up valuable oxygen needed by fish and other aquatic life.
Nitrogen and phosphorus from fertilizers and pet waste cause excessive algae growth, which further consumes oxygen and produces carbon dioxide. Other seemingly innocuous elements like silt and fine clay particles are flushed into our waters by rapid flowing runoff.
Sediment-loaded streams are said to have high turbidity. The result is habitat destruction for aquatic organisms. Gravel spawning beds are covered and interstitial spaces are filled. Micro habitats for nymphs and other fish food disappear.
Add to the equation things like road salt and warm runoff from sun-baked asphalt and we begin to see the perils facing our beloved waterways.
But there is hope. Through small personal efforts you can help improve our watershed health.
Rain gardens prevent water from flooding city streets, eroding landscaping and filling sewers, as seen in this July 6, 2015 photo:
Six Things Minneapolis College is Doing to Prevent Stormwater Pollution
Distribution of educational materials
Public participation (e.g. hold annual meeting with local community to discuss pollution prevention)
Storm Sewer Mapping
Strict erosion and sediment controls during construction projects
Installation and maintenance of stormwater treatment and management systems
Pollution prevention and good housekeeping (e.g., use of environmentally friendly lawn care products)
Minneapolis College Facilities Director
LHB, Inc. Consulting Engineer