Stormwater and Stormwater Runoff
Stormwater is rainfall or snow and ice that flows over the ground surface. Runoff is created by precipitation on roads, driveways, parking lots, rooftops and other paved surfaces that do not allow water to soak into the ground. Stormwater pollution occurs when debris, chemicals, sediment or other pollutants are washed into storm drains and flows into water bodies. The Clean Water Act (CWA) and its implementing regulations, requires that certain industrial facilities, construction sites and municipal separate storm sewer systems (MS4s) obtain coverage for their stormwater discharges under an NPDES permit, develop a Stormwater Management Plan (SWMP) and put measures in place to prevent discharges of pollutants in stormwater runoff.
Stormwater runoff is the number one cause of river impairment/pollution in urban areas. Where rain falls on paved surfaces, a much greater amount of runoff is generated compared to runoff from the same storm falling over a forested or grassy area. These large volumes of water are swiftly carried to our local streams and rivers by way of curbs and storm sewers. (Storm sewers, below, are the drains you see at street corners or at low points on the sides of your streets.) This volume of water entering the sewer system can cause flooding and erosion, thereby also washing away important habitat for wildlife.
Stormwater runoff similarly picks up and carries with it, many different pollutants that are found on paved surfaces such as sediment, bacteria, oil and grease, trash, pesticides and metals. These pollutants come from a variety of sources, including pet waste, lawn fertilization, cars, construction sites, illegal dumping, spills, and pesticide application. Researchers have found that as the amount of paved surfaces in the area increases, river health declines accordingly.
Downstream impacts of excess runoff include severe stream bank erosion (as shown here), loss of river habitat, and water quality problems, among others.
Since stormwater is naturally channeled to and flows through our underground storm sewer pipes to our river, there is no opportunity for treatment to remove pollution. Each of us must be careful to minimize or eliminate substances which may inadvertently pollute our river when it rains.
To counteract other impacts of stormwater runoff, municipalities have adopted regulations that require management of stormwater, for example, for all new development. Stormwater management is the use of specific practices, constructed or natural, to reduce, temporarily detain, slow down and/or remove pollutants from stormwater runoff. Stormwater management practices are essentially designed to restore or mimic some of the natural processes provided by the vegetative cover that existed prior to land disturbance. In many regions of the country, this native vegetative cover includes trees and shrubs.
Preserving undisturbed vegetative cover during land development is a much more cost effective approach than destroying these features and having to construct new stormwater management practices to replace the functions they originally provided. Trees, forests and other vegetation and their associated soils are often referred to as “green infrastructure” when they are used to manage stormwater runoff instead of, or in addition to pipes, pumps, storage chambers or other “hard infrastructure.” Municipalities are beginning to realize the many stormwater benefits of green infrastructure, and are encouraging the use of stormwater management practices that conserve forests and incorporate vegetative features.
How Do Trees Reduce and Remove Pollutants from Stormwater Runoff?
Trees and forests improve stream quality and watershed health primarily by decreasing the amount of stormwater runoff and pollutants that reaches our local waters. Trees and forests reduce stormwater runoff by capturing and storing rainfall in the canopy and releasing water into the atmosphere through evapotranspiration. In addition, tree roots and leaf litter create soil conditions that promote the infiltration of rainwater into the soil.
The presence of trees also helps to slow down and temporarily store runoff, which further promotes infiltration, and decreases flooding and erosion downstream. Trees and forests reduce pollutants by taking up nutrients and other pollutants from soils and water through their roots, and by transforming pollutants into less harmful substances. In general, trees are most effective at reducing runoff from smaller, more frequent storms.
In addition to these stormwater benefits, trees provide a host of other benefits such as improved air quality, reduced air temperatures in summer, reduced heating and cooling costs, increased property values, habitat for wildlife, recreation and aesthetic value.
Our Village recognizes the important connection between forests and stormwater runoff and thru our Forestry Department, opportunities are provided for residents to participate in The 50/50 Tree Planting Program. This aspect of the Village’s stormwater management plan supports a comprehensive watershed approach to improving water quality.
Combined Sewer Overflow (CSO)
What is a combined sewer overflow (CSO)? A CSO is a discharge from a combined sewer system directly into a waterway. A combined sewer system is designed to collect a mixture of rainfall runoff, domestic and industrial wastewater in the same pipe for conveyance to a wastewater treatment plant. The wastewater treatment plant for this area is the Metropolitan Water Reclamation District of Greater Chicago (MWRDCG).
The Chicago River has 37 CSO locations throughout the north suburbs running down to the city of Chicago. The MWRDCG has implemented a Combined Sewer Overflow Public Notification Plan to inform the affected public to include governmental organizations, civic groups, recreational groups or any public citizen of the occurrences of CSO on the Chicago area waterway system. Subscribe to CSO Notifications. The MWRDCG web site for CSO occurrences and further information can be reached at https://mwrd.org/stormwater-management-1 . Human Health Impacts of CSOs and SSOs.
For questions regarding the Village of Morton Grove storm water program, or to report a storm water problem, contact the Public Works Department at (847) 470-5235 or by e-mail at firstname.lastname@example.org.
Please report any illegal dumping or suspicious discharges to:
Morton Grove Public Works Department
Monday through Friday 7:00 am to 3:15 pm
Telephone Number (847) 470-5235
e-mail address email@example.com
After 3:15 pm Morton Grove Police, Non Emergency (847) 470-5208
For additional information regarding stormwater management please visit these Web sites:
The Water Cycle, Cloud Formation, and Rainbows Explained
(Many thanks to Megan with the Citizen Science Club for her suggestion)
(Thank you to Chrissy for her suggestion!)
How Humans Impact the Water Cycle
(Thank you, Amelia!)