From Denver Water (Jay Adams):
Denver Water cuts back on some of its West Slope supplies to help struggling streams.
The Colorado River is hurting.
The struggles of the river’s largest reservoirs, Lake Mead and Lake Powell, have been well documented over the last decade as drought has ravished the West.
The story, however, starts more than 500 miles upstream in Grand County, Colorado.
The county is filled with streams that make up the beginning of the mighty Colorado’s journey in the mountains north of Grand Lake. Around 60% of the water in Grand County is diverted from these streams and used for agricultural and municipal water supply, mostly on the Front Range.
That includes the Denver metro area, which receives about 20% of its water from Grand County, where Denver Water has water rights dating back to the 1920s. Most of the water is captured in rivers and streams around Winter Park when mountain snow melts in the spring.
But, after a lackluster runoff season on the West Slope combined with dry soils from the past year, the hot, dry conditions in early June meant the high-country rivers and streams needed help.
Denver Water responded by voluntarily reducing diversions from several Grand County creeks and coordinating with the Colorado River District, Grand County, Northern Water and other Learning By Doing partners to adjust operations, where possible, to help boost water levels in some of the more troubled areas.
“While our primary responsibility is to make sure we’re supplying water to 1.5 million people in the metro area, we’re always looking for opportunities to help improve conditions on the rivers, to help the aquatic environment, recreation and communities they flow through,” said Nathan Elder, Denver Water’s manager of water supply.
By reducing diversions, Denver Water foregoes collecting a portion of water it is legally entitled to collect for its water supply in exchange for improving streams and tributaries along the Colorado River.
It started with a plea for help
On June 5, the Colorado River District asked Denver Water for help after reporting extremely low water levels and critically high water temperatures on the Colorado River. The river district reported conditions were creating unhealthy habitat for fish and aquatic insects.
“When the email came in Saturday morning, we were in a position to quickly respond and reduce the amount of water we were pulling from several Grand County creeks,” Elder said.
Denver Water has continued making operational adjustments since that email.
The utility estimates that by early July it will have voluntarily foregone collecting around 11,000 acre-feet of water from Grand County to help keep more water in the Colorado and Fraser rivers. That’s roughly enough water to supply over 44,000 residences for one year.
“It has been helpful to hear directly from stakeholders in Grand County, including Trout Unlimited and ranchers along the river, on where we may be able to truly help the river, the community and the environment with our operational adjustments,” Elder said.
“With help from the West Slope, we’ve been able to target specific areas and send some beneficial water downstream.”
This includes adjusting water releases from Williams Fork Dam twice a day in a way that also benefits the Colorado River.
For example, when releasing water from the dam, Elder and his team try to time the flows, so the water reaches the river in Kremmling — an area prone to higher river temperatures — during hotter times of the day.
The higher water level helps to cool down the water, which is better for the aquatic environment.
Position to help
The wet spring conditions along the Front Range boosted water supplies in Denver Water’s South Platte River collection system, which drastically reduced customers’ demand for water across the metro area — where Denver Water serves a quarter of the state’s population.
In fact, from January to May, Denver Water’s customer water use hit a 50-year low across the metro area, despite nearly 600,000 more people in its service area since 1970. That includes years in which the metro area was on mandatory drought restrictions.
“Some of the low use may be due to COVID-19 impacts on business and obviously a wet, cool spring helped,” said Greg Fisher, demand manager for Denver Water.
“It’s a great sign that our customers really understand efficient water use and let Mother Nature do the watering for them when possible.”
This wet spring on the Front Range also helped provide additional flexibility on how Denver Water collected and distributed water across its collection system during the spring snow runoff.
“We were able to turn off the Roberts Tunnel in April, which helped bring water levels up in Dillon Reservoir for boating,” Elder said.
“The conditions also enabled us to send more water down the Blue River below Dillon Dam to help improve fish habitat around Silverthorne instead of sending the water to the Front Range.”
Denver Water uses the Roberts Tunnel to bring water from Dillon — the utility’s largest reservoir — under the Continental Divide to the Front Range.
But flexibility like this is not always possible, especially with the myriad threats Denver’s water system is facing.
“Between the rising temperatures, changes to the timing of spring runoff, extreme fire behavior and half a million more people expected in the metro area by 2040, our ability for flexible operations is decreasing in a time when we need it the most,” said Elder.
“We must take an ‘all-in’ approach that includes conservation, water reuse and development of new water supplies so we can continue to maximize the benefits of a large system.”
According to Elder, hot, dry weather conditions highlight the benefits of having a large water collection system, as it provides the water planning team more flexibility in its operational playbook.
The vision for the Gross Reservoir Expansion Project, which is in its final steps of permitting, is an example of how additional water storage can really help streams in times of drought.
“As part of the Gross Reservoir Expansion, some of the voluntary things we’re doing this year — like leaving more water in the Grand County rivers — will become required annual operations for us,” said Elder.
That’s because Denver Water is one of 18 partners who signed the Colorado River Cooperative Agreement in 2013, ushering in a new era of cooperation between the utility and West Slope stakeholders, all with the vested interest in protecting watersheds in the Colorado River Basin.
As part of that agreement, a process called “Learning by Doing” was created, which has helped the utility stay better connected on river conditions in Grand County. The partnership is a collection of East and West Slope water stakeholders who help identify and find solutions to water issues in Grand County.
“Denver Water has been part of Grand County for over 100 years, and we understand the impact our diversions have on the rivers and streams,” said Rachel Badger, environmental planning manager at Denver Water.
“Our goal is to manage our water resources as efficiently as possible and be good stewards of the water — and Learning By Doing helps us do that.”