Elevation Certificates in Discovery Bay, CA

Discovery Bay is a planned community built on the Byron Tract starting in 1964, with man-made waterways and residential islands that open onto the Delta. It is unincorporated, so it is mapped and regulated as part of unincorporated Contra Costa County, and its levees are the job of Reclamation District 800, which provides flood protection, drainage, water circulation, and bay access for about 3,600 properties on the tract. Flood mapping here has a specific history. RD 800 asked FEMA to revise the flood maps for Byron Tract, and on October 2, 2009 FEMA issued a Letter of Map Revision that removed properties from the Special Flood Hazard Area. RD 800's letter to owners at the time said those properties were rated in a low- to moderate-risk zone and were no longer subject to the federal mandatory flood insurance requirement.

That doesn't make floor height irrelevant. Levee-protected mapping depends on the levees keeping their FEMA accreditation, and FEMA's countywide study lists the 1-percent-annual-chance San Joaquin River level at Byron Tract as 9.9 feet NAVD88, with much of the Delta's land lying below the water on the far side of the levees. RD 800's current assessment proposal even uses each structure's finished first floor depth as a factor in the flood protection benefit, alongside a flood depth map. An elevation certificate gives you a certified number for that floor, which is useful for flood insurance rating if you choose to carry a policy, for buyers who want the data before closing, and as a baseline if a map or levee status ever changes. The certificate does not expire unless the building is altered in a way that changes the certified data.

On a Discovery Bay home we tie to NAVD88 with GNSS and use a Trimble S3 total station to measure the lowest adjacent grade, the top of the lowest floor, the garage slab, and the elevation of HVAC and utility equipment, including the bay side where the yard drops toward the water. We take the FEMA-required photos and sign Form FF-206-FY-22-152. If a lender has flagged a property that sits at or above the Base Flood Elevation, we can also prepare LOMA data and file through eLOMA when it qualifies. Start with our elevation certificate overview, or see Brentwood and Oakley.