Flood Warning System Protection in Vernon County, WI

 


 

Before flood control structures were built in Vernon County in Southwestern Wisconsin, widespread flooding was not uncommon. In 1954 a rainfall of just over 4 inches caused extensive damage across the county. Flood waters from the West Fork of the Kickapoo River covered the entire valley floor and every home in Avalanche had water in the first floor level. That same storm severely impacted railroads in Westby and Viroqua and nearly washed out a bridge on US Highway 14.

      Vernon County, Wisconsin 1954Vernon County, Wisconsin 1954

 

In response to these events, the County built a series of dams for flood protection: twenty ‐ two P.L. 566 Flood Control Structures. Most are located on private property and safeguard a combination of residential and recreation areas. Over time the County also created the Land & Water Conservation Department (LWCD) to manage the dam structures and to provide residents with an emergency action plan. The LWCD provides site specific information on each of the dams via their web site ( www.co.vernon.wi.gov/LWCD/damlist ), as well as evacuation routes, maps, etc. in the event of flooding caused by large runoff or failure of the structures.

In July 1978 the County endured a series of severe storms that resulted in hail and significant flooding. Vernon County was one of sixteen counties declared a disaster area by FEMA. Most the federal money went to repair damage around the community caused by the storm and did not include any provision for developing an early flood warning system. One of the main threats to dam integrity is extreme rainfall and the high flows that follow, and up until then, all monitoring, operations, and maintenance for the dams was done by a single LWCD employee. The LWCD had no means to simultaneously track water levels or to monitor rainfall throughout the watershed.

Then in the summer of 2007 and 2008 back‐to‐back 500 year floods were recorded. As Mark Erickson, Vernon County Resource Conservationist explains, “the floods we had in 2007 and 2008 were a wake ‐ up call to State and Federal officials and opened up the doors for funding”. In 2008 the County applied for and received a FEMA 404 Grant, as well as financial assistance from the Wisconsin Department of Military Affairs – Emergency Management. With assistance from HSE, a study was conducted later that year to help define the system goals, identify site conditions for an early flood warning system, and present ideas for communication, and possible future expansion.

HSE Flood Warning System Installation
HSE Flood Warning System Installation
      West Fork PK - Pilot Klinkner Dam at Town of Clinton, WI
PL566 Dam at Town of Clinton, WI

 

The County opted to stay involved in the flood warning system installation process (and gain hands ‐ on training), so in the Spring of 2009 HSE field technicians and LWCD Conservationist, Phil Hahn installed nine advance warning sites. The flood warning systems included packaged rain gauge stations with water level sensors that automatically transmit real ‐ time data (via VHF radio) to a base station in Viroqua.

The base station uses specialized flood warning system software. As part of the flood warning system initial set‐up, an overview map with nine sub‐screens was created so the County can track each site. Data shows rainfall and water level totals in a graphical display, as well as the rate of water level rise at each of the dams. When flood warning system alarm conditions are met, the software can send notification to LWCD’s Mark Erickson, and any other appropriate personnel, via text message and e‐mail. “The value of having an ALERT system is incalculable. . . It’s working great and we’ve incorporated the system into our first ‐ line ‐ of ‐ defense”, says Mark. “We don’t have to rely just on visual observations. When the water pools rise, the Sheriff's office is automatically notified and they can decide whether it’s time to evacuate residents downstream”.

 


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