SILT — Water managers are dealing with the after effects of the Grizzly Creek Fire and subsequent mudslides in Glenwood Canyon by continuing a water quality monitoring program.
The Middle Colorado Watershed Council received funding approval this week for the second phase of a program that will continue to collect and distribute data about weather and river conditions downstream of the Grizzly Creek burn scar. The Colorado Basin Roundtable approved $72,200 in state grant money for continued data collection at seven rain gauges in Glenwood Canyon, which will provide information to the National Weather Service, an automatic water quality sampler, soil moisture sensors, a new stream gauge and water quality monitoring station in the Rifle/Silt area and a data dashboard for easy access of the information.
The first phase of the project, which was implemented early last summer before the monsoons, addressed immediate water quality issues, collecting data at the rain gauges every 15 minutes.
The second phase of the project amounts to an early warning system that will let water users downstream of Glenwood Canyon know when dirty water from mudslides is headed their way. The MCWC hopes to have all the pieces in place before spring runoff.
“With the way post-fire events happen, we are going to be looking at impacts for the next two to five years,” said Paula Stepp, executive director of the Middle Colorado Watershed Council. “The part I’m really excited about is the cooperation between stakeholders and downstream users.”
On July 29, a heavy rainstorm triggered mudslides in Glenwood Canyon, which left some motorists stranded overnight, and closed Interstate 70 for weeks. Because soils scorched by the 2020 Grizzly Creek Fire don’t absorb moisture, the rain sent rocks, sediment and debris flowing down drainages, across the highway and into the Colorado River.
But the mudslides didn’t just affect the river at the site of the rainstorm. The cascade of dirty water also had impacts to agricultural and municipal water users downstream in Silt, whose only source of water is the Colorado.
The sediment-laden water caused problems for the town of Silt’s water treatment plant, which had to use more chemicals to get the sand to settle out. The increased manganese and iron suspended in the water gave it a brownish tint at taps. It also fouled a set of filters, which the town spent $48,000 to replace. The filters normally last four to five years, but had to be replaced after just one, said Trey Fonner, public works director for the town.
“If we knew what was coming down the river, we could shut off the intake and we could let the river clean up a little bit before we turned it back on,” Fonner said. “If our tanks are full, we can shut off and let the worst part of it go by.”
Conservancy district impacts
The mudslides also created challenges for the Silt Water Conservancy District, which delivers water from the river to about 45 headgates via a canal and pumphouse. Although the town can temporarily shut down its intake because it has about a three-day supply of water in storage, the conservancy district pumps water continuously and shutting off for a brief period of time is difficult.
“It’s not really a system that can be shut down easily,” said Nathan Bell, a consultant for the district and roundtable member. “It’s extremely cumbersome. It’s a nightmare.”
The main problem for the district is that the earthen canal which takes water from the river to the pump station silts up. The turbid water also acts like sandpaper, causing more wear and tear on the machinery and reducing its lifespan. The district is planning on more frequent canal cleanings and installing drop structures to catch the mud before it makes it to the pump house.
The data generated from the monitoring project will allow the district to better plan and budget for the inevitable increased maintenance and repairs, Bell said.
“It reduces the variables you’re having to manage,” he said. “It lets us get ahead of the game.”
The data dashboard will let downstream users and the general public set up text alerts for when a parameter of interest is too high or outside a specific window. Silt water users, for example, could set an alert for when rain gauges in Glenwood Canyon record a certain amount of rain, which increases the likelihood a plume of dirty water is headed their way.
The total cost of phase two of the project is nearly $1.3 million. The watershed council is asking the Colorado Water Conservation Board for about $650,000 in grant money and they also expect funds from the U.S. Geological Survey. Garfield County has committed to $15,000 over the next three years and the Colorado Department of Public Health and Environment will contribute $50,000.