Rivers rising in Weld with more rain and farmers using less irrigation water
May 28, 2014
The combination of rain, warm weather, a big snowpack and farmers recently cutting back on irrigating is pushing river levels higher in northeast Colorado.
The South Platte River and its tributaries were all above average on Friday, but particularly high was the Poudre River near Greeley, where flows were nearly four times higher than normal.
"You don't typically ask for it … but we need things to dry out right now," said Dave Nettles, the Colorado Division of Water Resources Division 1 engineer, based in Greeley, who noted he was "a bit alarmed" this week when he saw how much it was raining at Red Feather Lakes, northwest of Fort Collins.
Despite the increase, the Poudre River at Greeley didn't hit flood stage Friday. At 5:30 p.m., the river's height was about 6.7 feet, still below the flood stage of 8 feet, according to the National Weather Service.
The Weather Service's forecast called for the Poudre River to reach about 7.5 feet on Sunday, before leveling off and then falling some.
The South Platte River, too, was high, but not overflowing Friday. At Kersey — where all tributary rivers (the Poudre, Big Thompson and St. Vrain, among others) have dumped into the South Platte River — readings showed the river was at 7.2 feet at 5:30 p.m., well below the flood stage of 10 feet.
How high the rivers will get as the spring rolls on remains a bit of a mystery.
"You can expect the rivers to get at least a little higher," said Nettles, noting that the peak in flows on the Poudre River, for example, is typically around June 10 — still more than two weeks out.
All spring, river flows up in the mountains have been above average, thanks to a historically large snowpack.
But until recently, those river flows were weakening by the time they'd make it out to Greeley, because farmers in the area, battling dry and windy weather in March and April, were quickly diverting water out of the river to get their crops growing.
Now, with the recent rains, farmers aren't pulling as much water out.
"We're certainly not irrigating full on like we were recently," said Randy Knutson, who farms all around Greeley, and who also sits on various ditch and irrigation boards. "That's probably having an impact."
The abundant rain recently is a double whammy for those concerned about flooding.
The moisture not only stops farmers from irrigating, which lowers river levels, the rain also adds directly to the flows.
The agriculture industry uses about 85 percent of the state's water, according to the Colorado Division of Water Resources, and how it uses runoff has a significant impact on river flows.
Nettles noted that, while this year's snowpack is large, it's nothing like the historic snowpack of 2011, which caused some flooding, but nowhere near as destructive as what was seen this past September.
While the snowpack isn't as large now, there are other factors at play, Nettles noted.
Because of the 2012 and 2013 wildfires, there's less vegetation in the Poudre River basin capturing moisture, meaning more rain and snow is running off directly into the river.
As for other tributaries of the South Platte, like the Big Thompson and St. Vrain river basins, those are still littered with debris and compromised banks from September's flooding, which has long caused concerns for potential flooding in northeast Colorado during the spring run-off period.
"We're going to have high rivers this spring … that's for certain," Nettles said. "How high? That really depends on the weather. If things can dry out some, and we can get farmers pulling a little more water out of the river, the better off we'll be in that regard."