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RBC I The Colorado Water Conservation Board encourages property owners, recreationalists, businesses and communities to pay close attention to local waterways in coming days as stream flows in many rivers within the northern portion of Colorado are quickly increasing as warmer weather enters the state.
Forecasted temperatures have been on the order of 10 to 15 degrees above the seasonal average this week.
It is expected that major rivers in northern Colorado will experience their higher flows between now and June 10.
Currently, watersheds of greatest concern west of the Continental Divide are the Yampa River, Elk River, Colorado River and the North Platte River along with their major tributaries. Flood advisories have already been posted for Mesa, Moffat, Routt, Grand and Jackson Counties, with more expected shortly.
Lake County appeared on the watch list as well. Many of these rivers are already running well above the average flows for today’s date and many are at, or close to, bank full.
East of the Continental Divide, areas of largest concern are the Cache La Poudre River, the Big Thompson River and Clear Creek. These rivers are running much lower, but may quickly climb to higher peaks when warmer temperatures melt the abundant snowpack.
A “double peak” is certainly possible this year. This would involve peak flows happening in the near future during a warm spell, then dropping off due to cooler weather and then increasing again later in June. Although it is possible that some peak flows in rivers and streams may be on the order of levels seen in 1984 or 1995, it is important to note that the melting process is driven by the weather. Snowmelt flows are acutely affected by both high and low temperatures as well as precipitation (or the lack thereof) that falls in affected watersheds. While high water in streams that originate in Colorado’s high country is inevitable, severe damage from floods is not guaranteed.
Areas of greatest risk involve low lying lands and infrastructure adjacent to major rivers in Western Colorado and in the mountains and high foothills east of the Continental Divide. It is important to note that below about 7,500 feet east of the Divide, major floods are traditionally caused by heavy rain events, and the elevated snowmelt is unlikely to cause flooding. The primary impact to most Front Range metropolitan areas will be trail closures along streams and rivers, such as Clear Creek and Boulder Creek. The exception to this is the Cache La Poudre River in Larimer and Weld Counties, where snowmelt runoff can cause minor to moderate flooding on the plains depending on peak flows.
Residents and businesses with interests near rivers should continue to monitor water levels and contact their local emergency manager or floodplain administrator for updates.
All recreationists should be aware of the dangers of high water including the potential for floating debris, unfamiliar stream banks as waters rise above known features, cold currents and faster velocities.
The Colorado Water Conservation Board issues a daily flood threat bulletin and twice weekly 15-day flood outlook, which can be found at www.cwcb.state.co.us. A list of local emergency managers is provided by the Colorado Division of Emergency Management at http://www.coemergency.com/p/sources.html. A flood decision support system is also available to the public at http://flooddss.state.co.us/Default. aspx.