Elevation Certificates in Modesto, CA

Modesto grew up at the confluence of the Tuolumne River and Dry Creek, with the Stanislaus River to the north. The city's 2019 general plan environmental report notes that the mapped 100-year floodplain follows the river channels, from several hundred yards to about a mile and a half wide, and that there are no federal flood control facilities in the Modesto urban area. It also records the January 1997 flood, when the Tuolumne set a record height in Modesto and flooding reached urban neighborhoods next to the main channel. Dry Creek has no upstream reservoir, so its flows added to that event. The report also notes that the Tuolumne, Stanislaus and Dry Creek are state Designated Floodways, which brings state encroachment rules into play near the channels.

The flood maps here have been in motion. The 2019 report says the planning area's FIRM panels were generally last revised on September 26, 2008. In 2019 the city also asked residents to review FEMA's draft database for the San Joaquin, Tuolumne and Dry Creek flood risk project, and the City of Patterson's floodplain page describes the resulting Stanislaus County remap, prepared with Ceres, Modesto, Newman and Patterson, with a 90-day appeal period in 2020. Modesto's general plan policy is to approve new urban development only on findings of 200-year protection and compliance with the city's floodplain management ordinance in Title 9, Chapter 4 of the municipal code. For an individual owner, the practical questions are which panel now applies to the parcel and where the building sits relative to the base flood elevation. An elevation certificate answers the second.

In the field we tie to a published benchmark with GNSS on the FIRM's vertical datum, then use a Trimble S3 total station to measure the lowest adjacent grade, highest adjacent grade, lowest floor, garage slab, crawlspace and vents, and the machinery and utilities serving the building. Photos of each side of the structure go with the signed FEMA EC. If the grade at the building is at or above the BFE, we can prepare the elevation data for a letter of map amendment and file through eLOMA where eligible. Modesto work is scheduled as a mobilization from our base in Lotus. More: the elevation certificate service, Patterson and Turlock.