Elevation Certificates in American Canyon, CA

Elevation certificates and flood zone surveys for American Canyon in southern Napa County, between the Napa River marshes and the hills along Highway 29.

Elevation certificates from $1,000 · (510) 543-2220

Elevation Certificates in American Canyon: Local Conditions

American Canyon is a young city for flood mapping purposes. FEMA's Napa County Flood Insurance Study notes that the city had no flood study of its own before the first countywide study took effect on September 26, 2008, because until then it had been mapped as part of unincorporated Napa County. The countywide study was revised in 2010 and again on August 3, 2016, and the 2016 revision is the one that matters most on the west side of town. It replaced older tidal flood levels on the Napa River, which came from a 1984 Army Corps tide study, with FEMA's San Francisco Bay coastal analysis: regional storm surge and wave modeling, then shoreline transects using 2010 LiDAR.

Two details from that coastal revision are worth knowing if you own near the marsh. First, FEMA did not treat salt marsh berms or non-certified agricultural berms as barriers to flooding, whatever their height, so mapped flooding runs inland until it meets continuous high ground. Second, Base Flood Elevations along the bay are rounded to the nearest foot, while the zone boundary is drawn to a tenth of a foot from the LiDAR. A house close to the line can end up inside the zone on the map even though the ground at the foundation is at or above the BFE, and that is exactly where an elevation certificate and a Letter of Map Amendment (LOMA) can help. On the east side, the study notes that Napa County requires developers to upgrade channels enough to carry the 1-percent-annual-chance flood, and that short sections of American Canyon Creek were improved that way. American Canyon is FEMA community 060755.

The field survey ties to NAVD88 benchmarks using GNSS, then a Trimble S3 total station measures the lowest adjacent grade, highest adjacent grade, the top of the lowest floor, the garage slab, flood openings, and HVAC and utility equipment. We take the required photos and sign FEMA Form FF-206-FY-22-152. If the measured ground is at or above the BFE, we can prepare the LOMA and file it through eLOMA when eligible. Our elevation certificate page covers the process; nearby pages include Napa and Vallejo.

Full service details, process, and deliverables: FEMA Elevation Certificates & LOMA

What's Included

Signed and sealed by a California Professional Land Surveyor
Completed on FEMA Form FF-206-FY-22-152, with the required photographs
Elevations tied to a published benchmark on the flood map’s vertical datum
eLOMA submission as a licensed professional when the building qualifies
Construction-stage ECs for permits: construction drawings, building under construction, and finished construction
Sacramento region, Central Valley, Delta, and Bay Area

Our Process

Address & Flood Map Check

Send the address and the reason you need the certificate: lender letter, insurance quote, building permit, or a LOMA. We pull the effective FIRM panel, flood zone, and Base Flood Elevation before quoting, and tell you up front if a LOMA looks possible.

Benchmark Tie

We tie the site to a published benchmark on the vertical datum the flood map uses, with GNSS and a total station. Every elevation on the certificate is measured from that tie, not estimated from a contour map.

Building Measurement

We measure the top of the bottom floor, the next higher floor, the garage slab, the lowest and highest adjacent grade, the lowest machinery and equipment, and the flood openings, and take the photographs the form requires.

Signed EC, and the LOMA if It Qualifies

You receive the completed, signed Elevation Certificate as a PDF. If the lowest adjacent grade is at or above the Base Flood Elevation, we prepare the LOMA request and submit it to FEMA, through eLOMA when the building meets its criteria.

Elevation Certificates in American Canyon: FAQ

The Napa County countywide FIS took effect September 26, 2008 and was revised September 29, 2010 and August 3, 2016. The 2016 revision added FEMA's San Francisco Bay coastal flood analysis. Individual Letters of Map Revision can change panels between full revisions, so check msc.fema.gov.

Order an elevation certificate. If the lowest ground touching the house is at or above the Base Flood Elevation, FEMA can issue a LOMA removing the structure from the Special Flood Hazard Area, with no FEMA review fee. If it is below, the certificate is used to rate your flood insurance.

Not in FEMA's 2016 coastal mapping for Napa County. The study states that salt marsh berms and non-certified agricultural berms were not considered barriers to flood inundation, regardless of height or continuity.

Need Elevation Certificates in American Canyon?

Elevation certificates start at $1,000. Call (510) 543-2220 with the American Canyon address and we'll check the flood map and give you a fixed price.

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Private licensed surveyor, not affiliated with FEMA • Homeowners welcome • Response within 24 hours

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