Visitors to the High Line Canal corridor will see volunteers, botanists and tree trimmers making their way up and down the popular metro Denver greenway this summer.

The groups are implementing projects that are guided by the High Line Canal Conservancy’s comprehensive Community Vision Plan to preserve the natural qualities of the canal’s unique ecosystem and trail for future generations.

“For the first time in the canal’s history, we are documenting all the wildlife and plants along the greenway,” said Harriet Crittenden LaMair, executive director of the High Line Canal Conservancy. “We are also taking action by initiating a multi-year tree maintenance program that prioritizes safety for recreational users and the long-term health of the tree canopy.”

The 71-mile canal was built in the late 1800s to deliver water to farmers and ranchers and is in operation today. Denver Water owns the canal and still uses it to deliver irrigation water to about 60 customers stretching from Waterton Canyon to east Denver.

“The High Line Canal is going through a transition,” said Tom Roode, chief operations and maintenance officer at Denver Water. “It started as an irrigation canal, but now it’s used more as a recreational and ecological asset for our community that we want to preserve.”

The canal is an inefficient and outdated means of delivering water to customers losing more than 70 percent of the water to seepage and evaporation before it reaches customers.

That is why Denver Water is looking for alternative solutions to get water to customers who use canal water, freeing up the entire canal corridor for greater public benefit.

The change in operations will have an impact on the amount of irrigation water in the canal that supports the ecosystem, which is why Denver Water is working with the High Line Canal Conservancy and the local jurisdictions on the transition.

“The Conservancy, Denver Water and all the local jurisdictions recognize that part of being responsible stewards of the canal means planning for the future when things change,” Crittenden LaMair said. “As the water supply in the canal changes, we’re planning for the long-term preservation of the canal as a regional greenway that can still be an asset under a variety of water conditions.”

Tree care and trail safety

About 24,000 trees along the corridor were evaluated for safety and tree health in 2016. That information is now being used as part of the Tree Canopy Care Project, a multi-year, collaborative effort to accelerate tree care along the canal.

Arborists and contractors began working on the tree canopy in Aurora in June and will head down the entire 71-mile long stretch of the canal over the next 2-3 years.

“Many of the big cottonwood trees that line the canal are over 100 years old and as they get older, branches break off or the trees fall down,” said Brandon Ransom, recreation manager at Denver Water. “We’re removing trees that pose safety hazards to protect people on the trail.”

Arborists will trim dead limbs and branches to extend the life of trees that don’t need to be cut down, and will look for opportunities to promote wildlife habitat.

“While the trees may look healthy on the outside, we’re finding many trees with dead spots on the inside,” said Brian Aldrich, arborist foreman at Root Tree Services. “If we can save a tree we will, but if it’s dangerous, we’ll remove it.”

Plant inspection

The High Line Canal Conservancy partnered with Denver Botanic Gardens to document plant communities that line the canal for a project that began in April.

“There are hundreds of species of plants that have grown along the canal over the past 130 years,” said Christina Alba, research associate at Denver Botanic Gardens. “There’s a lot of diversity of native and non-native plants.”

Alba’s team carefully collects and logs information about the shrubs, grasses, herbs and vines from the foothills to the plains. The specimens will be kept at the Gardens’ Kathryn Kalmbach Herbarium and made available online.

The Conservancy and other canal partners will use the data to get a scientific evaluation of what types of plants thrive along the canal in dry and wet conditions. The findings will be applied to landscape design guidelines that are currently being developed in Framework Planning. These guidelines will provide recommendations for appropriate landscape standards along the canal.  

Watching for wildlife

Throughout the summer, the High Line Canal Conservancy is also hosting wildlife inventory events called BioBlitzes at various locations along the canal.

“We have volunteers and naturalists who are looking for birds, insects and mammals that call the canal home,” said Alana Weber, BioBlitz project manager for the High Line Canal Conservancy. “It’s fun catching butterflies, spotting furry animals and trying to identify all the birds we see and hear in the trees.”

Volunteers record their findings on an app called iNaturalist to create an online directory of the animals and bugs.

“The canal partners will use information gathered from the wildlife and plant studies to get a better understanding of what’s out here,” Crittenden LaMair said. “Findings will help in the overall landscape planning to guide decision-making for future management of the canal as a premiere recreational area.”

What’s next?

The High Line Canal Conservancy, Denver Water and jurisdictions along the corridor are looking at ways to use the canal for a variety of stormwater management projects.

The planning team continues to progress their work. With existing and canal-wide framework complete, the team is now working to identify areas of opportunity for enhancement and investment. This fall, the Conservancy will host public open houses inviting community feedback prior to the final release of the Framework Plan in October 2018. To stay informed about Framework Planning, visit highlinecanal.org/framework.

Denver Botanic Gardens’ team will continue documenting plant species through September and the High Line Conservancy will host three more BioBlitzes in July and August. Accelerated tree trimming and removal will continue through 2020.

Volunteers are needed for upcoming BioBlitz events in July and August. Contact Alana Weber: intern@highlinecanal.org