Thurston County Connection Newsletter
Thurston County Connection
Thurston County Connection
September, 2014
Subscribe to Newsletter
Search Past Articles
Browse Available Editions
County Connection
The Website
This Month's Articles

Back-to-School Safety 101:

Hope for the Best…..Prepare for the Worst!

Telephone Alerts Available for Flooding Hazards

The War on Food Waste

Little Red School House Drive a Big Success!

A Herd of Folks at the Thurston County Fair

Making it in the Dry Years

Thurston County Home
Send Editorial Feedback
to John Tennis
Problems using this site?
Contact the Webmaster
Website Disclaimer
 La Nina Increases Risk of Groundwater Flooding.

Are you prepared?

The La Nina winter and spring promises to continue to be a wet one. With increased rainfall comes the threat of groundwater flooding. In response to this threat, Thurston County Emergency Management sent information to county residents in areas prone to groundwater flooding. Frequently asked questions and answers about groundwater flooding are also posted on the county’s Emergency Management Website.

Here are some excerpts from the publication-

What causes groundwater flooding?

Groundwater flooding happens when soil becomes too saturated from rainfall to absorb more water and the water table rises to the surface. Much of the soil in Thurston County is glacial outwash—loamy sand or gravelly-sandy soils that drain well. The loose soils, however, allow water to travel in both directions. Soils that allow water to easily soak into the ground also allow water to rise to the surface when it hits an underlying layer of compacted soil or rock.

How high are local water table levels?

As of January, groundwater levels in several locations in Thurston County were less than 10 feet from the surface. Put into perspective, these levels were as high as last year’s peak at the end of the rainy season in April. Groundwater levels rose as much as three feet over 10 days in mid-December following 7.5 inches of precipitation that fell in this time span.

The county’s Resource Stewardship Department operates monitoring stations across the county. Water level measurements are collected hourly through electronic devices inserted in a well network. This data is used to create a monthly hydrograph of water level elevations. Details are available at the Monitoring website.

What can I do to protect my property?

The best long-term solution to groundwater flooding is to elevate your home on a new foundation. Tips and details on home elevation are available by contacting the county’s Resource Stewardship Department at 754-3355, ext. 6647. In the short term, we recommend the following measures:

1. BUY FLOOD INSURANCE (details below).

2. Elevate furnaces, water heaters, appliances and electrical panels.

3. Store paint, pesticides, fertilizers and other hazardous materials in plastic buckets or off the floor. Take unwanted hazardous items to the HazoHouse. Details at 754-3354.

4. Store important documents and irreplaceable personal objects where they won’t get damaged.

What about sandbags?

Unfortunately, sandbags are ineffectual in stopping groundwater from coming to the surface. When water is pumped, more groundwater is likely to rush in to fill the void. Unlike river flooding, groundwater flooding takes a while to subside because water has to find its way out of the groundwater basin toward the river.

Will Flood Insurance cover groundwater flooding? Yes! The National Flood Insurance Program offers insurance that covers damages due to groundwater flooding. National Flood Insurance, a federal program, is sold through many private insurance companies. It is the only dependable form of financial protection against flood damage.

The Standard Flood Insurance Policy defines a flood as-

A general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or two or more properties (at least one of which is your property) ... from unusual and rapid accumulation of runoff of surface waters from any source.

Through mitigation and preparedness actions, Thurston County has earned a 25% discount for flood insurance rates available to residents in the unincorporated areas. This translates into an an average annual savings of $238 per property. Complete details are available at Floodsmart. or by calling 1-888-379-9531.

Important: Act today! There’s a 30-day waiting period after the first premium is paid before the policy is effective.

How do I find out if my home is in a groundwater flooding area?

Major groundwater flooding areas are drainage basins of the following creeks: Salmon, Chambers, Yelm, Thompson and Scatter. High groundwater hazard areas are identified on the county’s GeoData Website. While the maps are not 100% accurate for every parcel, they do provide a wealth of information about high groundwater areas. Here’s how to find information on your property. Click on the website above and select parcel search. Enter your street number such as “2709” (street name is not required), and click “go.” Scroll until you find your address; then click on the parcel number to see details.

Read down the page to see information about your property, or click on “zoom map to parcel” at the top of the same page for a map. Click the square and the circle next to the feature you want to see on the map. (Hint: to identify the color coding of the maps, click on “legend” at the top of the page.)

By Keith Eisner

An example of ground water flooding in the county. An example of ground water flooding in the county.