It depends on how the lawn is cared for:
Good: Healthy lawns can reduce runoff
A dense, healthy lawn helps rainwater soak into the soil instead of flowing across hard surfaces. This can reduce erosion and slow flooding. [thelawninstitute.org]
Bad: Poor lawn care can create polluted runoff
Runoff becomes a problem when rain or overwatering washes lawn products into storm drains, streams, rivers, and lakes. Common issues include:
- Fertilizer runoff can add excess nutrients to waterways, contributing to algae blooms and water-quality problems. [iere.org], [iere.org]
- Pesticide and herbicide runoff can harm fish, aquatic insects, pollinators, and other wildlife. [blog.nwf.org], [theecoshift.com]
- Overwatering increases the amount of runoff and can carry pollutants away from the lawn. [iere.org]
Best practices
To get the benefits while minimizing harm:
- Apply fertilizer only when needed and follow label directions.
- Avoid applying chemicals before heavy rain.
- Water deeply but infrequently.
- Keep grass healthy and not cut too short.
- Use native plants, mulch, or rain gardens near drainage areas.
Bottom line: Lawn care itself is not inherently bad, but runoff containing fertilizers, pesticides, or excess water is generally harmful to nearby waterways. A well-managed lawn can actually help reduce runoff, while excessive chemical use and overwatering can make runoff a significant environmental problem. [thelawninstitute.org], [blog.nwf.org], [iere.org]
