It was fun to go behind the scenes for this story to see what the county is doing about salt entering the Colorado River. So many people depend on this water, from here to the Gulf of Mexico. Read the original version here:
Hold the Salt, Please
By Cecily Whiteside
Over 100 miles of canals trace their course through the Grand Valley servicing 34,000 acres of farm and residential land. They began being built in 1882, and Grand Valley Irrigation was founded in 1894 for management and upkeep of those canals. The climate, soil, and availability of water from the Colorado River made this an agricultural paradise. But water percolating through the dirt-sided canals, farmland and orchard soil, then back into the Colorado River, has a downside – salt.
When rainwater falls on desert little of it soaks into the ground which means that run-off tends to find its way back to the river above ground. However, when irrigation water soaks into the ground, watering crops and trees along the way, that water finds its way back to the river through the salt-rich rock and soil of the Grand Valley.
“With the 1972 Clean Water Act, the federal government made a strong commitment to reduce salt levels in the Colorado River system,” says Charles Guenther, Assistant Superintendent at Grand Valley Irrigation. “The Colorado River Basin Salinity Control Program has had several names over time, but has been around for years.”
The goal of the federally funded program is to reduce salt loading from the Grand Valley to the Colorado River for the benefit of the lower basin states and Mexico. That white residue that we see in fields after a rain is a naturally occurring but problematic side effect of crop production in our area. Water flowing through unlined canals seeps into the ground as well, adding to the salt-loading problem.
This is the third year in which Grand Valley Irrigation, with the help of a number of other local firms, has been lining the canals with a barrier to keep water flowing through them on the surface, and therefore reducing salinity.
Each fall, after the water has been drained from the canals for the winter, Grand Valley Irrigation goes to work. They have lined over 7 miles of canal so far, reducing the salt load to the Colorado by an estimated 10,300 tons.
“It’s a three-layer barrier under the shotcrete,” Charlie says. “A 30 mil PVC liner is sandwiched between two layers of geotextile fabric.” The geotextile fabric is there to protect what is basically a pool liner from rocks and other possible sources of damage. The shotcrete layer on top gives integrity to the barrier.
“The liner keeps the water in, and never sees the sun, so it’ll last a long time,” says Don Fowler, of Grand Valley Irrigation, as he checks the shotcrete levels with a gauge. “We bring the elevations up to within a 100th of an inch,” he adds, “so the water will flow downhill. It goes up toward Palisade.”
Each phase of the project completed to date is slightly different in length. All the work needs to be done before the canals fill for the summer.
“A lot depends on the weather,” Don says. “The mild winter really helped us move along more quickly this year. When there is a foot of snow on the bottom of the canal, we can’t do anything until it melts.” Last winter’s snow, which stayed on the ground for weeks, hindered the project but this year they were able to work most days. “We can’t pour in the rain or snow,” Don says.
Each day’s pour is covered by blankets for three days to keep it from freezing and to keep in moisture. “It makes the shotcrete dry slower to keep from cracking,” Don says. “We check the temperature every morning.“
Since the amount of salt loading have not yet reached desired levels, Charlie anticipates that the program will continue in upcoming winters. A lot of progress has been made already, though so as you see water running through the canals this summer think about all the “behind the scenes” work that has gone into reducing saline in the Colorado. Thanks Grand Valley Irrigation for holding the salt!
Published with permission of Grand Valley Magazine