Gilroy, CA Environmental Rules: Flood Zones (2026)

Chapter 27E's development permit requirement, Section 27E.15, reaches essentially every form of ground disturbance in a mapped special flood hazard area: new construction, manufactured homes, grading, filling, and drainage work all need a permit before work starts. The application must include scaled plans showing the location, dimensions and elevation of existing or proposed structures and material storage; proposed water, sewer, and utility locations; existing and proposed grading contours and drainage facilities; the location of the regulatory floodway where one applies; base flood elevation data; and the proposed elevation of the lowest floor of every structure, plus the floodproofing elevation for any nonresidential or mixed-use building under Section 27E.17(c)(2).

A registered civil engineer or architect must certify that a dry-floodproofed nonresidential or mixed-use building meets the chapter's floodproofing criteria, and crawlspace foundations must document the location and net area of flood openings required under Section 27E.17(c)(3). The floodplain administrator, the director of public works or a designee under Section 27E.13, reviews every permit to confirm the site is reasonably safe from flooding and that the project won't raise the base flood water surface elevation more than one foot anywhere in the city, per the duties listed in Section 27E.14.

Special flood hazard areas themselves are defined by the FEMA Flood Insurance Study and Flood Insurance Rate Maps for Santa Clara County dated May 18, 2009, plus the Uvas Creek Overflows Floodplain Management Study, adopted by reference under Section 27E.7. Appeals of the administrator's permit decisions go to the Gilroy City Council under Section 27E.16.