Depending on where you live in Marin, there may be local requirements governing drainage from new construction. Local codes usually follow basic California and case law regarding water rights. Typically downstream owners must accept the runoff flowing in natural channels, including peak storms. However, if an upstream owner has diverted stormwater from another water course, you may have some recourse for downstream damage. The first thing is to assess the nature of any upstream changes (if any). As a civil engineer and real estate broker, I've evaluated a lot of stormwater issues in the Bay Area, so email me with any specific questions.

Patrick Ritter, P.E.

patrick@PriRealtor.com

The best thing to do is to go down to City Hall to the planning department and ask. There are guide lines, though I don't know the exact verbage of it. But the bottom line is you need someone to help enforce it, if your neighbor is not adhering to it. If let's say there is a culvert on your neighbors property and the culvert is clogged, your neighbor is responsible for keeping clear. But the flooding could be also due to the home above him who knows. The best thing to do is to go down to The City explain the situation, they will let you know what you need to do and who to call to have an inspector come out.