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King County Flood Control District presents findings from Snoqualmie River hydrology study

Summary

Learn about changes in Snoqualmie River basin flooding by attending an April 18 meeting in Carnation with King County floodplain managers, King County Flood Control District Supervisor Kathy Lambert and independent consultant Ed McCarthy.

Story

The King County Flood Control District will hold a communityFlood Control Zone District Logo meeting in Carnation on April 18 to discuss results of a study about historical flooding patterns in the Snoqualmie River basin. The meeting is set for 6:30 p.m. in the Sno-Valley Senior Center, 4610 Stephens Ave.

Flood Control District Supervisor Kathy Lambert plans to attend. The consultant who conducted the study and Ed McCarthy, PhD, who provided an independent review, will also be at the public meeting.

“We heard from concerned residents along the lower Snoqualmie River that flooding seemed to be getting worse,” said Supervisor Lambert. “I took these concerns seriously and wanted them investigated.”
 
In response to community feedback, an independent consultant was hired to investigate how flooding has changed in the Snoqualmie River and what might be causing changes.

A first phase was completed in the spring of 2016 and looked at flooding impacts from two large river projects near Snoqualmie Falls. The April 18 meeting is to share findings from the second phase of the investigation, which looks more broadly at flooding changes throughout the river basin.

The draft study, “Snoqualmie River Hydrologic Study: Evaluation of Trends and Current Conditions,” looks at historic trends in river flow, precipitation, forestry, sedimentation, and other factors that affect flooding impacts. A peer review of the study’s findings was completed by hydrologist Ed McCarthy, PE, PhD and Certified Floodplain Manager.

The study’s findings show that the history of flooding in the Snoqualmie Valley has been very dynamic but that some trends can be found. There are clear signs of seasonal changes in flow and some evidence that flooding is happening more often.

Conclusive evidence that floods are getting bigger or arriving faster could not be found, though the study does highlight that particularly dramatic flooding has occurred in recent years.

The report also includes recommendations to improve river gaging for flood warning in the valley. 

The study provides a solid basis for understanding the past and current conditions in the Snoqualmie River. This information will be used to inform future efforts, such as the actions recommended by the Fish-Farm-Flood Advisory Committee.

To learn more about this study or submit comments, go to kingcounty.gov/rivers and follow the link for the Snoqualmie River Hydraulic and Hydrologic Study. The public comment period for the flood impact study ends May 3.

 

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The King County Flood Control District is a special purpose government created to provide funding and policy oversight for flood protection projects and programs in King County. The Flood Control District’s Board is composed of the members of the King County Council. The Water and Land Resources Division of the King County Department of Natural Resources and Parks develops and implements the approved flood protection projects and programs. Information is available at kingcountyfloodcontrol.org.