Floodplain cuts across Sisters

Over 40 residential lots in the Sisters city limits lie in the Squaw Creek floodplain. At least five homes lie inside the boundary of the "100-year flood."

According to the Sisters/Why-chus Watershed Analysis released by the Sisters Ranger District in October 1998, "Squaw Creek is subject to large floods and is a serious threat to homes and structures within its floodplain."

The U.S. Army Corps of Engineers released a study on the Squaw Creek floodplain in August 1978, which acknowledged that, "some residential and commercial buildings in the town of Sisters are located in the floodplain."

According to city officials, the houses that currently lie in the Squaw Creek floodplain were constructed prior to the mid '70s when the actual floodplain zone was established.

"This zone is intended to identify those sections of the urban area subject to the hazards of 100-year periodic stream flooding," says Sisters zoning ordinance 15.02.160. The city uses the 100-year flood line established by the Federal Emergency Management Agency.

The only current uses allowed in the floodplain zone include open space and parks, camping facilities, and geothermal exploration and development, each with certain exclusions and qualifications.

The Corps of Engineers estimated in their report that the 100-year flood would move 2,210 cubic feet of water per second (cfs) past the USGS gauge, about six miles above Sisters, and the 500-year flood would carry 3,390 cfs.

In comparison, the "Christmas Week" flood in Sisters in December 1964 moved approximately 1,980 cfs past the same location.