Sensors keep tabs on health of Grand County rivers
July 31, 2009
Each week, Bob Weiby puts on waders and heads down to the river.
Instead of casting a fly rod, however, this angler fishes for a tubular device anchored by a slate of cement.
From inside the protective plastic tubes, Weiby extracts small temperature sensors containing a week’s-worth of stored data on a chip recorded every 15 minutes.
As the field technician for the Grand County Water Information Network (GCWIN), Weiby then downloads this data, which becomes organized and part of a greater database of river information shared among those with water interests.
By 9:10 a.m. Wednesday morning, the Colorado River past Windy Gap had a temperature reading of 59 degrees, according to the monitoring device.
Weiby and GCWIN Executive Director Jane Tollett, a chemical/environmental engineer, explained how water temperature is a key component of river health.
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“The acute limit is 70 for much of the river,” Tollett said.
Last year, sections of the river near Parshall had frequent readings of 70 degrees in late summer, Weiby said, with 72 being the highest.
Temperatures in this range are detrimental to cold-water fisheries.
In water at such temperatures, fish can’t recover from the stress associated with catch and release, so anglers should not fish at water temperatures 65 degrees and warmer, Weiber said.
“For us, it would be like running a marathon and trying to recoup in a sauna,” he said. “At 65, it can take 15 to 20 minutes to revive a fish, and you may not be the only person who caught that fish.”
For five years, GCWIN has been building its monitoring arsenal, now made up of 28 temperature sensors in the river and this year’s addition of three air monitors on shore.
Since the sensors – called Tidbits – only last about five years, a recent campaign served to replace seven of them by donors in the community. The Network added 12 more, which cost about $130 apiece to replace.
“Every once in awhile, we find one pulled up on the river bank, and I’m sure it was by a well-meaning person who thought it was trash,” Tollett said.
GCWIN’s water temperature sensors are as far upriver as Mary Jane on the Fraser and downstream as far as Kremmling on the Colorado.
Data is collected from July to October, with about 25 percent of sensors remaining in rivers year-round. The data is most in demand during July, August and September when the river experiences its most critical temperatures.
Meanwhile, the Bureau of Land Management maintains five sensors near Kremmling and the Northern Colorado Water Conservancy District has its share of river monitoring.
The data GCWIN gleans from the sensors – with information about stream flows, air temperatures and water temperatures – has been used in the scope of Grand County’s Stream Management Plan, which has served well for negotiations with water users as both Denver Water and Northern Water work to firm up water rights for storing and delivering more water to populated cities.
“We’re here for the numbers. We want good data available to all those in the positions who make the decisions,” Tollett said. “There are some warm spots along the river, and we want to do whatever we can do to prevent further degradation. That’s why some of the mitigation work proposed by the (Windy Gap) firming project is so critical, such as deeper channels that will provide colder areas. It’s given the people in the county who are negotiating firming projects information they can use.”
GCWIN’s data is also being used by the Colorado Department of Public Health and Environment as it monitors upper Colorado River standards, she said.
GCWIN also collects lake water-quality data on the Three Lakes in Grand County and monitors temperatures at flows into lakes.
“All I can do is say, it doesn’t look like the high temperatures are going to go away,” Tollett said.
“All water is important. We want to protect it.”
– Tonya Bina can be reached at 970-887-3334 ext. 19603 or e-mail firstname.lastname@example.org.