How Low Impact Development Can Reduce Stormwater Runoff And Protect Water Quality

The Problem Of Polluted Storm Water:
After heavy rainfall, water flows down rooftops, sidewalks, parking lots and streets, carrying everything from sediment to pesticides. In some areas, polluted runoff flows directly into waterways. In others, runoff combines with sewage to overwhelm treatment systems, spilling raw or partially-treated sewage into waterways and the Great Lakes.

The Connection To Sprawling Development:
Development is one of the biggest threats facing the Great Lakes and inland waterways. Current land development involves grading a site, removing native vegetation, and covering the natural landscape with concrete, asphalt and buildings. As a result, the ground becomes less able to absorb water and filter pollution like a natural ecosystem, instead creating polluted runoff. One quarter of Michigan watersheds are vulnerable to impact (or already impacted) by contaminated runoff from developed land. Current forecasts predict that Michigan will add over 4 million acres of new development by 2040, nearly tripling the amount of built land.

Low Impact Development (LID):
LID aims to reduce stormwater runoff and protect water quality by making the built environment function like the natural environment. It is a strategy applied at the parcel and subdivision scale that utilizes on-site, natural features (e.g. native vegetation) and low-cost, engineered controls (e.g. rain barrels) to maintain predevelopment stormwater flows.

LID benefits the environment by preserving native vegetation and preventing stormwater flows that cause flooding and erosion, destroy habitat, and carry pollutants into waterways. LID also benefits communities and developers by improving the value of developed properties and reducing the need for costly stormwater infrastructure improvements.

Local Solutions:
With many communities implementing the National Pollution Discharge Elimination System (NPDES) Phase II requirement, now is an ideal time to engage local decision-makers and promote LID. In Michigan, local governments make zoning, land use and stormwater management decisions. Master plans, zoning ordinances, and stormwater ordinances should explicitly endorse and encourage LID techniques that residents and local leaders find desirable and are within the goals of smart growth, while revising older parts of ordinances that inhibit effective stormwater management.

How To Get Involved:
The best way to ensure LID is implemented locally is to become an active participant in your community. One of the most important ways to effectively advocate is to clearly and powerfully communicate your message. To assist grassroots groups and citizens, Environment Michigan has created a media packet that includes a model op-ed, press release and letters-to-the-editor describing the problems with stormwater runoff and the way local government can help by encouraging LID. We have also compiled the most important principles for drafting a model ordinance and has links to the best examples of local governments incorporating LID principles into local building codes.

Check out "Waterways at Risk," our recent report investigating the impact of stormwater runoff in Michigan and the benefits of LID.

Specific LID techniques include:

• Vegetated roofs
• Permeable paving
• Bioretention areas (e.g. rain gardens, swales)
• Rain barrels
• Preserving natural vegetation
• Clustering development & preserving open space
• Designing buildings and roads to minimize impervious surface cover

Key Terms:
Integrated management practices (IMPs): the set of most effective and feasible practices for maintaining predevelopment stormwater flow; alternately termed “best management practices” (BMPs).

Impervious surface: a surface that does not allow water to infiltrate
No-net runoff: a site that has successfully utilized LID techniques such that conveyance of stormwater runoff to traditional stormwater drainage systems is not necessary.