RIDGWAY – The Town of Ridgway’s water storage capacity will soon increase exponentially, as the town launches a project this fall to improve its municipal reservoir, fondly known as “Lake O” – short for Lake Otonowanda.
The $2.4 million Lake Otonowanda Rehabilitation Project will allow the town to exercise its full decreed storage right by improving the lake’s capacity from 100 to 600 acre feet, while restoring the tunnel outlet near the reservoir to make the delivery system more efficient.
The town’s municipal water right on Lake O predates the Colorado River Compact, a 1922 deal made by seven U.S. states in the basin of the Colorado River in the American Southwest, which to this day governs the allocation of the water rights to the river’s water.
Currently, due to Lake O’s modest size and declining condition, the Ridgway stores only a fraction of the water to which it is legally entitled; the renovation will allow the town to maximize Lake O's historic adjudicated capacity. Stored water will supply the town when its flow rights are out of priority, ensuring enough water for most anticipated situations, even during drought years, and accommodating growth well into the future.
When the renovation is complete, the town will be able to supply water to the community for a minimum four-month period in a drought event, compared to its current storage capacity of only 10‐14 days’ worth of water.
The rehabilitation project got the big green light earlier this month, when the Town of Ridgway finalized a $1.2 million grant/loan package with the Colorado Water Conservation Board that will contribute significantly toward financing the project.
(The CWCB’s Water Supply Reserve Account provides money for grants and loans to complete water activities, including water supply and environmental projects and/or studies.)
A WELL-FUNDED WATER STORAGE SOLUTION
Arguably among the most scenic municipal reservoirs in the nation, Lake O is located about three miles south of Ridgway off of County Road 5, in an alpine meadow encircled by ponderosa forests and pristine views of the Cimarrons and Sneffels mountain ranges. It is the town’s primary municipal water source; the town also holds junior flow rights on Beaver Creek and Cottonwood Creek/Happy Hollow that are more vulnerable to calls. Generally, the lake provides enough water for the town’s needs (with an average of 280 acre feet diverted each year), but in the drought of 2002, all of Ridgway’s water rights were called by downstream senior water rights holders. The state water engineer subsequently put the town on notice to shore up water rights and storage strategies to prevent this situation from happening again.
In the ensuing decade, the town examined several water augmentation scenarios, ranging from purchasing augmentation water from Tri‐County Water Conservancy District’s Ridgway Reservoir to securing more senior water rights from local agricultural users in a so-called “buy and dry” solution.
TCWCD was not receptive to providing treated water for the town in response to a call, nor was the town pleased about the buy and dry concept, which in effect diverts irrigation water to municipal purposes. A feasibility study by the Applegate Group, completed in 2011, found the Lake O renovation project to be the town’s best option for water augmentation, and the wheels were set in motion for the project that is about to break ground.
The Lake Otonowanda Rehabilitation Project, in its entirety, will cost $2.4 million; over half of that will be covered through grant funds from the Department of Local Affairs, the Colorado River District, the Colorado Water Conservation Board and the Gunnison Basin Roundtable; the remainder will come from a $600,000 loan from the CWCB and in-kind contributions from the Town of Ridgway.
The town has raised its base rate for water users by $5 per month per user every year since 2010 to cover the debt service from the CWCB loan.
TRAVELING BACK IN TIME
Lake O has been used as a municipal reservoir for nearly 100 years. In the beginning, it was a privately held water supply for the Ridgway Townsite, established as a railroad community in the late 1800s. Town fathers acquired the reservoir as a municipal water storage site in the early 1900s, when Ridgway was a flourishing supply center for the Denver Rio Grande Southern Railroad.
The town has done its best to maintain the historic reservoir over the years, but conditions have nevertheless deteriorated significantly.
The first phase of the rehabilitation project seeks to repair the historic outlet works, which collapsed decades ago. Parts of the original outlet tunnel were relocated through geotechnical work completed in 2012.
“Locating and viewing the tunnel has been like traveling back in time, as we have been curious for many years how the tunnel was designed and constructed almost a full century ago to bring water to the town,” said Town Manager Jen Coates.
Currently, due to the collapsed tunnel, water must be pumped out of the reservoir with a diesel powered generator to the town’s ditch and pipeline. “Restoring the outlet works will allow the water to flow to town without having to be pumped,” Coates said.
The second phase of the project – the bulk of which takes place next year – will increase the lake’s storage capacity. This phase will entail some excavation of the property, and portions of the expanded lake bed may need to be lined. The Town of Ridgway is currently working with a private property owner who owns a portion of the Lake O basin, to allow the basin to be inundated. Coates said the property owner is open to working with the town.
Some wetlands restoration is also planned, and the town has explored opportunities to incorporate a micro‐hydro system to capture energy from the gravity flow in the future.
“We hope to break ground on the project this fall, but the bulk of the lake renovation work will occur next year,” said Coates. “Most of the cost is excavation.”
Town officials estimate that the project represents a 30-50 year solution for the town’s water needs, based on projected population growth.
“It’s a great project,” Coates said. “It’s not a ‘buy and dry,’ and it keeps Colorado water in Colorado. The basin is there. The tunnel outlet is there. And it is being primarily paid for through grant funds. A supply plan is better than an augmentation plan. We are investing in our own storage.”
The project has gone out to bid, and the award for the tunnel outlet portion of the project should be announced later this week.
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