Silver lining: Lining canals to cut for salinity also boosts efficiency — The #GrandJunction Daily Sentinel #ActOnClimate #ColoradoRiver #COriver #aridification

From The Grand Junction Daily Sentinel (Dennis Webb):

Winter may be the offseason when it comes to a lot of construction work, but for ongoing efforts to line local irrigation canals, it’s the only practical time for further pursuing multi-year efforts to line them.

Doing so locally helps address salinity problems throughout the Colorado River Basin, meaning that irrigation entities can tap federal funds to pay for much of the work. But it also provides the side benefit of making canals able to deliver water more efficiently, in higher volumes, multiplying the payback for the millions of dollars that get invested in such work.

In September, the federal Bureau of Reclamation announced that it will distribute $33.7 million for salinity control projects in western Colorado over the next three to five years. This includes nearly $4.7 million for the Grand Valley Water Users Association for continued lining of the Government Highline Canal, and about $1.23 million to the Grand Valley Irrigation Company for a fifth phase of lining it has been doing over the past decade or so thanks to Bureau of Reclamation salinity control funding.

Lining canals limits seepage of water into the ground, where that water can pick up salt before eventually reaching the Colorado River, which is relied upon by downstream states and Mexico. High salinity in the river reduces crop yields downstream for farmers reliant on the river water, and can increase water treatment costs and corrode things such as household appliances, reducing their useful life.

In Colorado, salinity control efforts by the Bureau of Reclamation also include the operation of a deep injection well for salty groundwater in Montrose County’s Paradox Valley. While that project has been highly effective in salt removal, it is increasingly causing earthquakes and the future of the Bureau of Reclamation’s Paradox desalination program is uncertain as the well nears the end of its serviceable life.

23,426 TONS OF SALT A YEAR

In the Grand Junction area, groundwater reaching the river percolates through Mancos shale associated with an inland sea that left salt deposits behind tens of millions of years ago. The Bureau of Reclamation estimates that a total of $37.2 million it will distribute to 11 projects in western Colorado and Wyoming over the next few years will keep about 23,426 tons a year from entering the Colorado River.

The last lining work the Grand Valley Water Users Association did on the Government Highline Canal was finished last year and ended at 36-3/10 Road in the Palisade area. The work being undertaken now will pick up from there and run to 35 3/10 Road, covering some 6,100 feet of canal length, said Mark Harris, the association’s general manager.

The canal is operated by the association and owned by the Bureau of Reclamation. The project the new funding will cover most of will take place over three winters, and Grand Valley Water Users Association is covering about 10% of the cost through cash and in-kind contributions.

The funding the Grand Valley Irrigation Company is getting will be used for work on close to a mile of the Grand Valley Canal over multiple years, on stretches running by Bookcliff Gardens and the Crown Point Cemetery area. Phil Bertrand with the Grand Valley Irrigation Company said the hope is to get about 300 or 400 feet lined in the first phase of that work this year.

Grand Valley Irrigation’s project involves a little more than $149,000 in matching funding, according to the Bureau of Reclamation.

Harris said the work on the Government Highline Canal will include restoring its shape where needed. A fuzzy geotextile layer will be laid down to help protect the water-sealing PVC liner that’s put on top of it from the underlying earth and rocks. The PVC liner is covered with another fabric liner, and then three inches of concrete are added on top to help protect the canal from abrasion from sand and silt flowing through the canal.

A drainage system also is being installed below the canal to help control the accumulation of underlying groundwater that can damage the canal lining when it is drained due to pressure exerted on it. The water in the canal when full otherwise counters that pressure…

Canal lining also reduces seepage that can impact adjacent private property. In addition, it can reduce the amount of selenium that also leaches along with salt into the river. High selenium levels in soil are particularly a concern in the Gunnison River Valley, and high levels in the Gunnison and Colorado rivers can threaten wildlife including endangered fish…

Harris said some sections along the Government Highline Canal cause more salt loading in the river than others. Localized levels of salt underground, the underground geological structure in an area and how much water that seeps from the canal actually makes it to the river all can play roles in salt loading, and areas of the canal with a lot of seeping aren’t necessarily where lining results in the most reduction of salt…

GUNNISON PROJECTS

The Uncompahgre Valley Water Users Association got more than $5 million in funding, and Grandview Canal & Irrigation Co. in the Crawford area received more than $6.3 million. Needle/Rock Ditch Company, also in the Crawford area, is receiving about $4.24 million, and Pilot Rock Ditch Company in eastern Delta County is getting more than $940,000. The Turner Ditch Company near Paonia will receive about $6.15 million.

All of those projects entail installing pressurized pipe. Some involve matching funds and others are being completely paid for by the Bureau of Reclamation.

A local initiative called the Lower Gunnison Project tries to take advantage of salinity-control funds and leverage them with other funding sources to make projects go further, Kanzer said. That project’s goals are wide-ranging, from reducing salt and selenium loading in the Gunnison River, to pursuing more efficient delivery and on-farm application of irrigation water, to improving soil health and boosting agricultural productivity…

WETLANDS MITIGATION

Canal-lining projects also can have wetlands projects associated with them. Where wetland habitat is destroyed as a result of the work, it has to be replaced elsewhere, Harris said. In the case of the Grand Valley Water Users Association project, crews will be creating new wetlands at the Colorado River Island State Wildlife Area south of D Road. Harris said the project will involve some 1,500 plantings and will result in creation of habitat far superior to what is being replaced…

The Grand Valley Water Users Association’s canal project is occurring as the association also is in the middle of work to replace electrical and operating equipment at the Grand Valley Diversion Dam, the roller dam in De Beque Canyon. Harris said such projects “all kind of fit together” in improving water delivery in the Grand Valley, but are expensive. It’s hard for the association to pay for something like the current lining project internally through assessments, he said.

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