Remembering the Northfield flood of September 2010, the U.S. Geological Survey is installing new river gauges on the Cannon River near Northfield to improve flood forecasting and high water management.
The instruments will take hourly readings of the river's height and volume and send the information to the National Weather Service via satellite. The Weather Service will use it to forecast floods.
Two gauges are being installed on the Cannon -- one in Northfield and another near Faribault -- and two gauges will be positioned on Chubb Creek near Randolph and Prairie Creek near Cannon Falls, upstream of Lake Byllesby. Total cost for the four is about $70,000.
Currently there is just one gauge on the Cannon River in Northfield, and someone from the Weather Service had to drive out to read it. It also did not work reliably in high water.
The new instruments are the response to the severe 2010 floods which caused extensive property damage and threatened the safety of the Byllesby Dam, said James Fallon of the U.S. Geological Survey.
As rain falls, getting information from the first gauge will give Northfield a couple of hours of warning before high waters arrive in town, Fallon said.
Dakota County -- which owns and operates Byllesby Dam to back up the Cannon River to create a recreational lake -- will monitor the river gauges to see how much water is coming into Lake Byllesby from the Cannon and its tributaries. It will use the information to decide how much water to hold in the reservoir and how much to release at the dam, said Tom Berry, zoning administrator for the county.
The U.S. Geological Survey will operate and maintain the gauges and add their data to a national record it keeps on water availability and resources.
Staff from the survey will regularly take measurements in person to supplement the gauge readings.
Diane Cooper, service hydrologist for the National Weather Service in Chanhassen, said the agency has river gauges around the region, including Stillwater, Jordan and St. Paul.
"If a community has a concern and they need to know for preparedness, this [a gauge] is one of the elements that has to be established," Cooper said.
The early information from Northfield is already being posted online, she said.
Before the recent snowstorm, the Weather Service was monitoring dry conditions and noting the level of the river and creeks at low flow.
When spring arrives and the winter snowpack melts, the information will then be used to establish what water levels create flooding, Cooper said. It will be able to say, for example, at what level certain roads will be underwater and at what level evacuations may be necessary.
Laurie Blake • 952-746-3287