Elevation Certificates in Rio Vista, CA

Rio Vista owes its location to a flood. FEMA's Flood Insurance Study for Solano County says the town started in 1857 near where Cache Slough meets the Sacramento River and was washed away by floodwaters after the prolonged rains of the early 1860s. It was rebuilt about three miles downstream on its present site. The ground there runs from about 5 to 70 feet in elevation, with the Montezuma Hills to the southwest. Marina Creek, Marina Creek Tributary and Industrial Creek drain the town east-southeast to the river. The waterfront has flooded several times since. In March 1907 high river flow and high tides flooded every building in the waterfront district and put Front Street under water except at its high southern end. The river channel below town was enlarged between 1917 and 1927, and minor waterfront flooding followed in 1955, 1958 and 1973. On February 20, 1986 the Rio Vista tide gage peaked at 8.8 feet, which FEMA estimates exceeded the 1-percent annual chance flood.

The Sacramento River Flood Control Project shapes flood protection here, with levees, weirs, bypasses and upstream reservoirs from Shasta County to the American River. Near town, the Army Corps' National Levee Database lists the Mellin Levee, a 1.173-mile earthen levee that is part of that federal project. It reduces flood risk from the Sacramento River for residential, industrial and farm land, and the Central Valley Flood Protection Board is the non-federal sponsor. In town, the FIS notes that Rio Vista's zoning ordinance sets up floodway districts, and a regulatory floodway is designated along the lower 0.75 mile of Industrial Creek. Building in a floodway is tightly restricted, so it helps to know exactly where your lot sits before you plan work there.

Solano County's FIRM uses NAVD88, so we tie a benchmark on that datum before measuring lowest adjacent grade, the lowest floor, the garage, and machinery such as HVAC and water heaters. We photograph the building and certify the EC. If the ground at the structure is at or above the base flood elevation, a letter of map amendment can remove the structure from the Special Flood Hazard Area, and we can file it through eLOMA when the request qualifies. See our elevation certificate service, or nearby Fairfield and Antioch.