Legal Question in Real Estate Law in California

Re: No recorded Easement, but city drainage channel

Storm drains such as you describe sound a lot like natural drainage, i.e. seasonal creeks. For the same reasons L.A. County doesn't need an easement for the Los Angeles River, it doesn't need one for lesser streams. I'm at home now and answering from memory, not library references, but terms such as 'thalweg' 'alodial ownership' and 'public trust' come to mind.

The public trust doctrine says that beaches, streams, lakes etc. are at all times inherently owned by the public, and the government, acting as trustee for the people, can sell, grant, lease or otherwise dispose of only such interest therein as does not compromise the public's interest in such lands. In this case the reserved interest would be for leading off storm waters. I think this is the applicable law.

Also, no one owes you compensation for features of the land that are plainly evident to a purchaser exercising ordinary diligence.

If anything, you may have a claim under your title insurance unless there is an exclusion that covers the drainage system.

So, my first impression is that you have somewhat limited rights as an owner to the drainage channels, which seem to be 'concretized creeks,' but I can't give you the precise law at the moment and some other LawGuru attorney may have a second opinion for you.