Work underway to smooth out big drop in river near Basalt
Anderson Falls, associated with a midvalley diversion ditch, will be no more
Work currently underway in the Roaring Fork River between old town Basalt and Willits will make for a smoother ride for boaters beginning this spring.
The project, with an estimated price tag of $935,000, requires a temporary cofferdam during construction across much of the river’s channel, with heavy machinery in the exposed river bed. It will create two new “grade-control” structures to replace a weir that was used to channel water toward a diversion for the Robinson Ditch. That weir created a difficult passage for boaters that was often referred to as Anderson Falls.
Instead of that steep drop with no clear passage around or through, the project has been designed by Carbondale-based River Restoration to create a gradual riffle drop between the grade-control structures. The Robinson Ditch diversion structure, which delivers raw water for outdoor irrigation from April through October to customers in the Mid Valley Metropolitan District, will also be rebuilt as part of the project.
Work on the project, which was approved for funding in March by Pitkin County’s Healthy Rivers and Streams board of directors, began in December and is permitted to take place through March 15, said Quinn Donnelly, an engineer with River Restoration.
The weir, he said, created “probably one of the bigger navigation hazards” on the Roaring Fork, resulting in many boaters avoiding that stretch, which is just above a boat ramp near the FedEx facility off of Willits Lane.
“We are trying to make a natural riffle here” that meets the needs of boaters, Donnelly said. Making that stretch of the middle Roaring Fork more accessible might also have the added benefit of taking pressure off other stretches of river and more crowded boat ramps farther downvalley, he said.
The project should also improve fish habitat as water scours the riverbed around the newly placed boulders.
The cofferdam is blocking the river across most of the channel, funneling the Roaring Fork’s winter flow into a series of culverts on river right. On Thursday morning, an excavator was picking up 3- to 6-foot-diameter boulders and arranging them in a line to form the upper grade-control structure. The site is visible from the bike path connecting Willits Lane to Emma Spur.
Donnelly said that most of the boulders that were being placed this week will be buried by alluvium below “scour depth,” with more rocks placed on top. The project has been designed to keep the ditch headgate clear of sediment and debris carried downstream.
Once the grade-control structures are completed, the current cofferdam will be removed. A second temporary cofferdam will be installed at river right to allow for the new headgate to be built. That, too, will be removed before the project is complete and the river flows unimpeded through the section.
As of last year, project planners had secured $256,200 in grants, including a $171,216 Colorado Water Plan grant and a $45,000 Water Supply Reserve Fund grant from the Colorado Water Conservation Board, as well as a $40,000 Fishing Is Fun grant from Colorado Parks and Wildlife.
Pitkin County’s Healthy Rivers fund, supported by a 0.1% sales tax, will cover the difference when all grants have been applied, said Lisa MacDonald, who works in the Pitkin County Attorney’s Office and provides staff support for the Healthy Rivers program.
MacDonald and Donnelly credited the Roaring Fork Conservancy and the Roaring Fork Fishing Guide Alliance for supporting the project. Donnelly noted that in any river project, there are myriad interests in play involving water users, riparian habitat and recreation. It is a balancing act, he said, but a successful model involves bringing stakeholders together and that has been the goal here.
Robinson Ditch Co. president Bill Reynolds, who is also the director of the Mid Valley Metropolitan District, said he’s happy to see the project making progress and believes it will enhance the experience for river users.
The ditch company paid for the engineering and design of its diversion infrastructure, he said. That infrastructure makes it possible for users in a wide swath of the midvalley to irrigate using raw water, as opposed to more-expensive treated potable water, which the district also provides via a series of wells, he said.
Ditch companies typically rely on government grants to make infrastructure improvements, he said, expressing gratitude for Pitkin County’s model of supporting river projects.
“Pitkin County and the funding mechanisms they’ve been using have been a blessing,” Reynolds said.
Aspen Journalism is a nonprofit, local, investigative news organization covering water and rivers in collaboration with The Aspen Times and other Swift Communications newspapers. For more, go to aspenjournalism.org.