Steep, wooded and almost all single-family
About 95% of Orinda's homes are detached houses, 91% are owner-occupied, and the median home was built in 1960 (U.S. Census). Lots cut into wooded hillsides mean long driveways, retaining walls and cuts at the back of the house, all places where water collects after a long storm.
What usually goes wrong
| What you see | Likely fix |
|---|---|
| Water across the driveway or into the garage | Channel drain at the bottom of the slope, piped to an outlet |
| Grates and gutters clogged with leaves | Larger grates, debris baskets, cleanouts and pre-storm cleaning |
| Wet strip or seep behind the house | Interceptor drain uphill of the house |
| Erosion below a pipe outlet | Rock apron or other energy dissipater at the outlet |
| Water at a retaining wall | Wall back-drainage; engineer if the wall is moving |
Downspouts and grates on wooded lots: downspout drainage and catch basins.
Watch the slope after long storms
The USGS tied most damaging Contra Costa County landslides from 1950 to 1971 to long storms on ancient landslide deposits (USGS Bulletin 1388). If you see new cracks, tilting walls or fences, or doors that suddenly stick, read the hillside warning signs and call a geotechnical engineer before drainage work.
Permits, fire district and Moraga
- Ask the City of Orinda Planning Department which permits your drainage or grading work needs before digging.
- Moraga uses Contra Costa County for plan check and inspection (Town of Moraga), and protects native, orchard and historic trees.
- Both towns are served by the Moraga-Orinda Fire District, which runs annual exterior hazard inspections. Coordinate drainage plantings and dry creek beds with any vegetation clearance requirements on your lot.
Costs on steep lots
Deep hillside drains in the Bay Area run about $75–$100+ per linear foot (Cardona Construction), and hand digging on steep, narrow lots adds time. See the cost guide and the contractor checklist.
Orinda and Moraga questions
Why do drains on Orinda lots clog so often?
Wooded lots drop leaves, needles and twigs onto grates and into gutters, and steep driveways carry debris downhill to the lowest grate. Larger grates, debris baskets, cleanouts and a pre-storm cleaning routine help.
Who issues permits for drainage or grading work in Orinda?
Start with the City of Orinda Planning Department, which will tell you what applies to your project. In Moraga, plan check and inspection go through Contra Costa County.