08/26/2026
In a natural landscape, rain soaks into the ground, filtering through soil and replenishing local groundwater, streams, and lakes. But as communities grow and develop, open spaces like forests, parks, and grassy areas are replaced with rooftops, driveways, and parking lots. Water has nowhere to go. Instead of soaking in, it rushes across these hard surfaces, picking up oil, sediment, fertilizer, pet waste, and other pollutants before flowing into storm drains and directly into local waterways, untreated. This is what impervious surfaces do, and it is one of the leading drivers of nonpoint source (NPS) pollution. Studies have shown that up to 70 percent of the pollution in our streams, rivers, and lakes is carried there by runoff from practices carried out in our own yards and gardens.
The more impervious surface a community has, the worse the problem gets. More pavement means more runoff, more flooding risk, and more pollutants reaching Oakland County's five major river watersheds. In August 2014, Southeast Michigan experienced firsthand what that can look like when massive storms dropped four to six inches of rain in four hours, resulting in major flooding on roads, freeways, and parks across the region.
The good news is that practical solutions exist. Green infrastructure helps manage stormwater closer to where it falls:
- Plant trees: certain species of mature trees can absorb over 2,800 gallons of water annually, significantly reducing runoff volume
- Install a rain garden to capture runoff from rooftops and driveways and filter it naturally through the soil
- Choose permeable pavement for driveways and walkways so water can filter through rather than run off
- Disconnect downspouts and direct them onto grass or garden beds instead of pavement
- Add mulch and native plantings to bare soil areas to slow and absorb rainfall
Green infrastructure doesn't just protect water quality. It reduces flooding, cools neighborhoods, creates wildlife habitat, and can even lower water management costs for the whole community.
Sources: canr.msu.edu/news/soak_up_the_rain_part_1 | canr.msu.edu/news/why_do_we_need_rain_gardens