A government agency cannot be held liable for inverse condemnation by reason of erosion caused by inadequate storm drainage facilities unless the agency owns those facilities. Here, as a condition of approving subdivision maps, defendant county required the developers of two subdivisions along a creek to build storm drainage facilities in the creek adjoining the subdivisions. The county also required the developers to dedicate drainage easements to the county. However, the county did not accept dedication of the drainage facilities themselves, and merely charging fees for eventual improvement of those facilities when and if the federal government granted enough funds to build them, was not enough to make the county the owner of the existing drainage facilities. So the county was not liable for the damage caused when the creek overflowed those drainage facilities which were owned by the subdivision homeowners.