Traditionally, Michigan communities have managed stormwater through “grey infrastructure” such as storm drains, sewer pipes, basins, and in the case of combined sewer areas, wastewater treatment plants. These carry large capital costs for installation, and the centralized nature of gray infrastructure means failures can discharge hundreds or thousands of gallons of untreated stormwater into nearby water bodies (a combined sewer overflow, or CSO).
Runoff from rain or melting snow can substantially affect water quality in nearby streams, rivers, and lakes. Impervious surfaces like roads, parking lots, and buildings prevent runoff from penetrating into soil, leading to flooding and erosion. Runoff also picks up and carries pollutants, pathogens, litter, and sediment. The resulting water contamination can lead to algae blooms, declining ecosystem health, beach closings, and no-swim advisories. Lake Erie’s recurring problems with toxic algal blooms can be traced partially back to excess nitrogen and phosphorus in runoff from agricultural fields and urban areas.
Green infrastructure is an approach to stormwater management that protects natural drainage patterns and mimics the natural hydrologic cycle. The most common forms of green infrastructure rely on plants and other natural materials to capture and slow rainwater or snowmelt as it moves across a landscape. That way, water can percolate through the soil and plant roots can filter out contaminants. Green infrastructure can also be used to absorb rising water levels and prevent flooding.
Green infrastructure solutions can be implemented on differing scales. On the local scale, green infrastructure practices include rain gardens, permeable pavement, green roofs, infiltration planters, trees and tree boxes, and rainwater harvesting systems. At the watershed scale, green infrastructure includes preserving and restoring natural landscapes such as forests, wetlands, and riparian buffers. Green infrastructure projects can also help communities improve safety and quality of life, conserve vital ecosystem functions, and mitigate the effects of heavy rainfall and flooding.
Historically, many river shorelines were stabilized and hardened with concrete and steel to protect developments from flooding and erosion, or to accommodate commercial navigation or industry. Typically, shorelines were developed for a single purpose. Today, there is growing interest in developing shorelines for multiple uses and benefits. Soft engineering is the use of ecological principles and practices to reduce erosion and achieve the stabilization and safety of shorelines while enhancing habitat, improving aesthetics, and saving money.
Green infrastructure at home
Green infrastructure can be a great way to encourage eco-friendly practices at home, at work, or in the classroom. Here are a few steps you can take:
- Plants are experts at trapping and slowing rainwater and snowmelt. Choose native plants and trees that are adapted to the amount of sun and water your region receives. Put mulch around plants to keep water from evaporating out of the soil.
- Opt for less lawn. Mowed grass forms a dense surface that makes it harder for water to penetrate into the soil, requiring more water than other types of planting arrangements.
- Plant rain gardens near downspouts, storm drains, or other low spots where water tends to accumulate.
- Buy or build a rain barrel. Read how household rain barrels help reduce runoff and lower water bills, and learn how to make and decorate your own rain barrel!
- Consider installing permeable or porous pavement on your driveway instead of concrete or asphalt.
- If you live near a pond or lake, leave a strip of plants (called a “riparian buffer”) along the water’s edge.
- Support local efforts to conserve green spaces, protect wetlands, and add public rain gardens and bioswales.
Michigan Sea Grant and partners have studied runoff and green infrastructure in west Michigan’s Spring Lake and in southeast Michigan. Find final results from those projects below.
Donald D. Carpenter, PhD, PE, LEED AP
Professor of Civil Engineering
Lawrence Technological University
Sanjiv Sinha, Ph.D., P.E.
Vice President & Corporate Leader – Water Resources
Environmental Consulting & Technology, Inc.
Avik Basu, Ph.D.
Lecturer and Research Area Specialist
University of Michigan