Independent resource
Rain that lands on your roof
doesn’t have to leave your property.
A rain garden is a shallow, planted depression that catches roof and driveway runoff and lets it soak into the ground instead of running to the storm drain. Done right, it handles a one-inch storm from an average roof and needs almost no maintenance after the second year.
Rain garden guides
Sizing, soil testing, plant selection, cost, and maintenance — the full build sequence.
Runoff calculator
Enter a catchment area and soil type. Get the runoff volume and the rain garden size that handles it.
French drains
Yard, foundation and basement — the same trench at three depths, and what each one costs.
Seawalls and riprap
Holding a shoreline in place: walls, bulkheads, rock revetment and living shorelines, with costs and the permit path.
Why runoff is the whole problem
An ordinary 1,500 sq ft roof sheds roughly 900 gallons in a single inch of rain. On undeveloped ground that water soaks in slowly and recharges the water table. On a roof and a driveway it arrives at the creek within minutes, carrying oil, brake dust, and lawn chemicals with it, and it arrives with enough force to scour the gravel beds that salmon spawn in.
Slowing that water down at the parcel scale is the cheapest available fix. It is also the only one a homeowner can do alone.
Start with the calculator. Almost every rain garden that fails was built the wrong size for its catchment. Size yours first, then dig.