About the Floodzilla Gauge Network

The Snoqualmie Valley Preservation Alliance’s (SVPA) Floodzilla Gauge Network monitors water levels throughout the Snoqualmie Valley, in real-time. This flood monitoring network is the innovation of a group of local technology professionals who have volunteered their time and expertise to develop this tool for the benefit of the community. Paid staff and consultants have also contributed to the project with funding through SVPA’s generous donors and with a grant from King County Flood Control District.

The Floodzilla Gauge Network relies on a series of SVPA gauges placed in strategic locations to monitor water levels in drainage ditches, farm fields, on public roads, and on the Mainstem Snoqualmie River. The SVPA gauges are ultrasonic sensors that have been programmed to read and transmit water level data every 15 minutes during flood season, from October through May.

While the USGS gauges have provided reliable Snoqualmie River water level data to valley residents for decades, there is only one gauge on a 30-mile stretch of river between the USGS Snoqualmie Falls gauge at river mile (RM) 40, and the USGS Duvall gauge at RM 10. During flood events, there can be a significant, and unpredictable lag between the timing of upstream flooding in the Fall City/Carnation area and flooding further downstream near Duvall. The SVPA Floodzilla Gauge Network fills in this data gap with gauges on the river and in nearby farm fields and ditches, giving the farmers, residents, and commuters vastly more information to prepare.

Historical data screenshot of Floodzilla Website on Feb. 1st 2020 at SVPA-15 gauge, along NE 124th St. near Duvall Washington (left). And the full picture of the flooding happening in the surrounding area with an icon for the gauge location (right).

Sign Up for Floodzilla Alerts

Users can sign up for specific alerts on our Floodzilla phone app. Our alert system provides two different types of alerts. One alert is from the Northwest River Forecast Center (NWRFC) flood predictions, which measures water in cubic-feet-per-second (cfs). This alert provides NWRFC’s date and time predictions at three different locations: Below the Falls, Carnation, and Forks. The “Forks” refers to the sum of three upper Snoqualmie River branches of the river. Many people often look at the cfs sum of the three forks (North, Middle, and South) above Snoqualmie Falls to determine how much water will end up in the lower valley below. And scientific prediction tools use this cfs measurement to predict if there is enough water to leave the banks of the river.

Once water begins rising in the lower valley, SVPA Floodzilla gauges are capturing water level height (in NAVD88 Vertical Datum) and transmitting that data every 15 minutes. We provide alerts for when water levels at specific Gauge Sites change their status to “Flooding”, “Near Flooding”, and “Normal” or “Dry”. These alerts are based on adjacent road elevation levels, so you can see how close the water is to the nearby road in the alert.

Flood impacts to local roads is of significant importance to farmers, residents, and commuters. Most roads that go under during flooding do not flood as a result of overbank flooding from the river, but instead, from inundation of adjacent ditches or fields.

Due to the complex landscape of the Snoqualmie Valley, The SVPA Floodzilla Gauge Network monitors water levels not only in the river, but also provides information to the public whether or not there is water on a particular road, as well as how deep it is.

This is helpful when roads are not flooding yet, as they show height of the water relative to the spot where the road first goes under. Some farmers and land managers live offsite of their farm, and knowing when it is safe to return after a flood is incredibly important.

We hope you find this information useful! If you have any questions about the SVPA’s Floodzilla Gauge Network, please contact us at info@svpa.us or call the office at 425-549-0316. Regina Fletcher regina@svpa.us is the Field Scientist for this project.

Slide the following images back and forth to see our contribution to flood monitoring sites:

Over the course of the 2022-2023 academic year, a Seattle University Senior Design team, composed of Jamie Elrod, Ruby Hooper, Sean Tachibana, Owen Trampe, and supervised by Dr. Lee, worked with SVPA and the Floodzilla Gauge Network Team to developed an automated and efficient screening algorithm to improve data accuracy displayed to users as well as developed an approach to display inundation maps on the Floodzilla website. These inundation, or flood, maps expand the accessibility of flood-related information to the public and the screening algorithm greatly reduces the need for manually removing erroneous data from SVPA-operated gauges.

The Senior Design teams accomplishments with this project led them to achieving first place in both the Environmental and Water-Related Issues’s annual WSP student Design Competition held in Nevada and the Annual American Society of Civil Engineers competition held in Seattle.

 To view their final report, click HERE. 

Geary Eppley

Floodzilla Creator and Project Manager

Regina Fletcher

Floodzilla Field Scientist

Dave Sanderman

Software Engineer

Pavlo Babenko

Software Engineer

Dean Vergillo

Structure Design and Installation Specialist

The Floodzilla Gauge Network is the product of community collaboration and innovation. Program Creator and Manager, Geary Eppley, has volunteered countless hours over many years to developing this tool for the Snoqualmie Valley Community. He works side by side with SVPA staff, contractors, and other volunteers to continue managing and enhancing this important resource. Our Floodzilla Software Engineers as well as our Gauge Structure Design and Installation Specialist provide their services to us significantly below market rate and often donate many hours of work entirely in-kind as they are dedicated to ensuring Floodzilla remains an accessible and useful tool for Snoqualmie Valley residents, businesses, visitors, and land managers.

The community support doesn’t stop here though… we also partner with private landowners and local government to host our gauges on site as well as our network connectivity equipment. Our data stewards and gauge stewards play a very important volunteer role in helping our staff maintain gauge sites and ensure the most accurate data is displayed on the Floodzilla website.

We can never thank all these incredible individuals enough for everything they do to keep Floodzilla up and running and accessible to all of us in the valley.

THANK YOU!