Lexington County redefines flood-prone areas near creeks, ponds

Lexington County public works officials are revising maps of areas around creeks and ponds long thought likely to flood, setting the stage for smaller insurance bills for some homeowners.

Updates so far have reduced the size of flood plains set 30 years ago in 15 neighborhoods scattered across the 758-square-mile county, according to a report to County Council.

The review underway uses “much more accurate” techniques to determine areas prone to flooding instead of continuing to rely on estimates based on terrain, county flood plain manager Chris Stone said.

Information on where water is expected to rise helps set homeowners’ insurance rates for those areas.

So far, reviews of areas along 25 miles of streams and ponds discovered 798 homes were classified improperly as in jeopardy of flooding, the report said.

That opens the way for those homeowners to reduce or cancel extra insurance required for dwelling at high risk of flooding, savings that can be several hundred dollars a year.

“It’s striking how much money can be saved simply by going and looking a little closer at this,” Councilman Todd Cullum of Cayce said.

The neighborhoods reviewed were built before county officials adopted a requirement nearly a decade ago that developers must determine flood-prone areas before building and stay out of them.

Most sites checked so far are in rural areas, but a few are in Cayce, Irmo and West Columbia.

Those neighborhoods were checked due to density of development and complaints from residents that flood plains previously set appeared too large.

County officials are focusing on neighborhoods along small streams and ponds.

Setting flood plain boundaries around Lake Murray, the lower Saluda River and the Congaree River is a job left to federal officials. Construction in those flood plains must meet certain criteria. Floodways close to those water bodies are where the water is most likely to rush in a flood. Federal laws prohibit almost all construction in those areas.

So far, county officials have reviewed 1,700 of 20,000 acres recognized as flood plains along streams and ponds.

The job takes several months to finish in each neighborhood, Stone said.