City Council OKs new Issaquah Creek flood gauge
November 23, 2009
By Warren Kagarise
NEW — 6 a.m. Nov. 23, 2009
City emergency planners will soon have a new tool to monitor rising flood waters: a new Issaquah Creek flood gauge.
Though workers will install the gauge early next year, the device will not be calibrated and ready until the next flood season. City Public Works Operations Director Bret Heath said the city would be able to collect data from the gauging station in the meantime.
Heath, who also serves as the city’s emergency management director, said the existing flood gauge arrangement has “a bit of a blind spot.” Heath said the new gauge should fill the gap.
City Council members approved $33,000 for the gauge Nov. 16, about a month before the expenditure was scheduled for a vote as part of the 2010 city budget. Heath had requested money for the new gauge in the proposed spending plan, but during a presentation last month about the January flood, council members urged Heath to present the proposal for a vote as soon as possible.
The full city budget is scheduled for a Dec. 21 vote.
When Issaquah Creek flooded in January, the flood warning system did not reflect the magnitude of flood waters flowing downstream toward Issaquah, because large amounts of runoff from the 15 Mile Creek drainage off Tiger Mountain entered Issaquah Creek downstream of the upstream flood gauge.
Planners said the new gauge will provide more accurate Issaquah Creek flood data, with about 45 to 60 minutes’ warning of impending flood waters, the City Council legislation states.
Readings from another flood gauge also did not correlate with the damage caused by flood waters, city Emergency Management Coordinator Steve Campbell told the City Council last month.
A U.S. Geological Survey gauge downstream on Issaquah Creek appeared inaccurate, because the device indicated about 2,500 cubic feet per second during the flood. But subsequent damage was similar to the 3,500 cubic feet per second estimate from the last major flood to hit Issaquah, in 1996.
Heath said city staffers would also work with the USGS team to recalibrate the gauge.
Floodwaters left behind about $1 million worth of damage when Issaquah and Tibbetts creeks overflowed in January.