SEASIDE — Residents in Gearhart, Seaside, Cannon Beach, Clatsop County and Warrenton’s Diking District No. 1 will be unable to buy flood insurance, renew existing flood insurance policies and will face additional consequences unless their jurisdiction adopts new federal flood insurance rate maps.

The urgent message resonated at an open house Monday at the Seaside Civic and Convention Center, where locals looked over draft revisions to the Federal Emergency Management Agency’s maps that identify flood risk along the coast.

Adoption of the maps — which will be used to set flood insurance rates and shape community development decisions — will involve new flood hazard ordinances.

“It’s pretty dire if the cities and county are unable to move forward with the adoption of these ordinances,” said Patrick Wingard, regional representative for the Oregon Department of Land Conservation and Development.

A community that fails to adopt the maps will be suspended from the National Flood Insurance Program and face a host of sanctions.

Not only will residents be ineligible for flood insurance, the community will not qualify for federal grants or loans for development in flood hazard areas, or for federal disaster assistance to repair insurable flood-damaged buildings in those areas.

“If you are suspended from the National Flood Insurance Program, that affects folks’ ability to get mortgages; it affects the business climate, the local economy and the regional economy,” Wingard said.

The communities will mostly benefit from the mapping updates, which are the result of a countywide study that began in 2009 and incorporate the latest topographic technology.

The bottom line: Far more land was removed from the 100-year flood plain than was added to it.

The 100-year flood plain has a 1 percent chance of flooding in any given year and a 26 percent chance of flooding during the life of a 30-year mortgage, according to Heather Hansen, the county’s flood plain manager.

“Each of the cities here that have been involved in this particular study area saw reduction,” said Jed Roberts, a flood mapping coordinator with the Oregon Department of Geology and Mineral Industries.

Warrenton’s Diking District No. 1 — now provisionally accredited by FEMA — boasts a 9.2 percent net reduction in flood hazard area; Gearhart a 7.7 percent reduction; Seaside an 8 percent reduction; and Cannon Beach a 27.4 percent reduction.

Robin Risley, a Realtor who sits on the Cannon Beach and Clatsop County planning commissions, expects many property owners in Seaside and Cannon Beach to be “happily surprised” by the results.

Though some acreage was added to the flood plain, much of it is undevelopable anyway, like property along the ocean that may be subject to high-force winds and wave impact, Hansen said.

The county, she added, has already mailed letters to property owners in unincorporated areas who will see a portion of their land added to the flood plain on the revised maps.

A separate set of preliminary flood plain maps is undergoing a technical review funded by the cities of Warrenton and Astoria, Clatsop County, the Port of Astoria and Diking District No. 9. The stakeholders argue the maps exaggerate the flood risk and would force property owners into paying extra in flood insurance.

The next step is a 90-day appeal period, which David Ratté, flood plain engineer with FEMA Region X, said he anticipates will begin in late September or early October when the agency publishes notifications in two local papers of record.

Assuming FEMA doesn’t receive any significant appeals, the agency may issue a letter of final determination to the communities in spring 2017.

Then follows a six-month adoption period for communities to update their flood plain ordinances. When the six months is up, the flood insurance rate maps become effective.

Wingard urges anyone with concerns about the maps to raise them during the appeal process so the hearings on the ordinances during that crucial six-month window can play out uninterrupted.

“Hopefully, folks will understand that the cities and the county have a lot at stake,” Wingard said.

Maps online:

Click on “Map Layers” tab and select “Draft FEMA Revisions 2016.”