Purpose of the report: This rapid assessment, produced by the Western Water Assessment (WWA), serves as a scientific resource for understanding drivers and impacts of the flooding events that occurred from October 10th -14th, 2025 in southwest Colorado. The report is designed to support local resilience building efforts and hazard planning for communities in the region. It provides the longterm and recent historical context for the flooding, hydrologic characteristics of the flood event, and an assessment of the local probability of an event of this magnitude.
Key Findings:
• The October 10th-14th, 2025 floods were the 3rd largest on record for Pagosa Springs, CO, with river levels reaching a maximum gauge height of 12.82 feet and peak flow rates of 8,570 cubic feet per second
• A total of 12.5 inches of precipitation fell at a high-elevation observation site in the watershed over 5 days, saturating the watershed and driving the river to reach Major Flood stage twice in that period
• Flood frequency analysis based on historical observations of runoff in Pagosa Springs suggests this flood has a return period of 25 to 40 years, meaning that there is a 2.5-4% likelihood of a flood of similar magnitude occurring in any given year.
• Early reports following the flooding suggest that hundreds of residents and households were evacuated in Pagosa Springs and surrounding rural communities and many structures were damaged or destroyed by the floods including homes, bridges, and roadways.
• Nearly two decades of exposure to drought conditions, increasing wildfire activity, and now the recent flooding collectively highlight the geographically unique and increasingly frequent natural hazard risks that rural mountain communities face in southwest Colorado.
Supporting future resilience: Understanding the drivers, characteristics, and likelihood of extreme events like the floods of October 2025 is crucial for effective resilience planning. Scientific analysis that is tailored to local communities, like this assessment for Pagosa Springs and Vallecito, provides specific, actionable information that planners and residents can use to understand their unique exposure to hazards. The Western Water Assessment (WWA) is committed to providing usable science to support hazard planning and response in communities across Colorado, Utah, and Wyoming.
For further information on how WWA can support your community, please reach out to our team at wwa@colorado.edu.
Denver Water and Save the Colorado must enter mediation at the end of the month to see if a deal is possible on the mid-project challenge to the water utility’s $531 million dam raising underway at Gross Reservoir in Boulder County, according to an order from the U.S. Court of Appeals.
A federal trial judge initially halted construction on the nearly finished dam, saying the U.S. Army Corps of Engineers permits for Denver Water violated U.S. environmental laws and that the water level at Gross could not be raised. Judge Christine Arguello later lifted the injunction on construction, for safety reasons, while Denver Water appealed the permit issues to the 10th Circuit Court of Appeals.
The 10th Circuit will take briefs from both sides of the dam dispute in November, and is now ordering a mediation session for Oct. 30. The conference is to “explore any possibilities for settlement” and lawyers for both sides are “expected to have consulted with their clients prior to the conference and have as much authority as feasible” on settlement questions, the court order says.
Construction has continued since the injunction was lifted, with Denver Water pouring thousands of tons of concrete to raise the existing dam structure on South Boulder Creek. Denver Water has argued it needs additional storage on the north end of its sprawling water delivery system for 1 million metro customers, to balance extensive southern storage employing water from the South Platte River basin.
Denver Water’s collection system via the USACE EIS
Save the Colorado and coplaintiffs the Sierra Club, WildEarth Guardians and others argue too much water has already been taken from the Colorado River basin on the west side of the Continental Divide, and that the forest-clearing and construction at Gross is further destructive to the environment. Gross Reservoir stores Fraser River rights that Denver Water owns and brings through a tunnel under the divide into South Boulder Creek.
“We look forward to having a constructive conversation with Denver Water to find a mutually agreeable path forward that addresses the significant environmental impacts of the project,” Save the Colorado founder Gary Wockner said.
When securing required project permits from Boulder County, Denver Water had previously agreed to environmental mitigation and enhancements for damages from Gross construction. But Save the Colorado and co-plaintiffs sued to stop the project at the federal level, and Arguello agreed that the Army Corps had failed to account for climate change, drought and other factors in writing the U.S. permits.
Denver Water declined comment Tuesday on the mediation order.
The halt and restart of the Gross Dam raising came in what has turned out to be a tumultuous year for major Colorado water diversion and storage projects.
While the Gross Dam decisions were underway, Wockner was finishing negotiations with Northern Water over $100 million in environmental mitigation funding to allow the $2.7 billion, two-dam Northern Integrated Supply Project to move forward. Once the 15 communities and water agencies subscribed to NISP water shares saw the increasing price tag, some began pulling out.
Northern Water reviewed the scale of NISP with engineers, then said it planned to move forward at the previously announced scale. The consortium’s board has asked all 15 initial members to indicate by Dec. 31 where they stand with the project and its price tag.
Roller-compacted concrete will be placed on top of the existing dam to raise it to a new height of 471 feet. A total of 118 new steps will make up the new dam. Image credit: Denver Water.
Fun beaver/fish interaction: When I approached this pond, I startled brown trout preparing to spawn below it (beavs filter sediment & keep downstream substrate clean). The fish dashed to the dam & hid in its base. Beavers created perfect spawning grounds: pristine gravel adjacent to dense cover! 🤯🦫🐟
The October rains that changed this water year in the San Luis Valley came at a particularly critical time.
In September the closely-watched unconfined aquifer hit its lowest level ever recorded since monitoring of the troubled aquifer began in January 2002, according to the Davis Engineering report given at Tuesday’s quarterly meeting of the Rio Grande Water Conservation District.
Knowing that, now imagine the conversations that would be happening in the Valley’s farming and ranching community had there been diminished or no October rains. The year was shaping up to be among the worst for flows on the Upper Rio Grande and readings on the unconfined aquifer reinforced it.
Then October delivered heavy rains across the southwest, which resulted in historic fall seasonal flows on the San Juan and into the Rio Grande and Conejos River systems. The Rio Grande grew by 80,000 acre-feet and the Conejos River by 20,000 acre-feet as a result of the rains, said Craig Cotten, division engineer for the Colorado Division of Water Resources.
Colorado is now estimating a total annual flow of 470,000 acre-feet on the Upper Rio Grande, up from its earlier estimates for the year at 390,000 acre-feet. Still, the irrigation year on the Rio Grande will likely end on Nov. 1 as scheduled, said Cotten.
“That’s a big amount of water in just a short amount of time,” he said in noting the latest accounting for Rio Grande Compact purposes.
2026 budget hearing set
The Rio Grande Water Conservation District set a 2026 budget work session for Nov. 24; then a public hearing to adopt next year’s budget on Dec. 11. The water conservation agency is proposing a year-over-year increase to its mill levy. It is proposing a 1.75 mill levy property tax, up from 1.6 mills in 2025.
Rio Grande and Pecos River basins. Map credit: By Kmusser – Own work, Elevation data from SRTM, drainage basin from GTOPO [1], U.S. stream from the National Atlas [2], all other features from Vector Map., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11218868
This shows how buffaloes were pushed west by white immigrants—just like Native Americans. No coincidence the last years on it coincide with the end of the US Wars on the Indigenous. Also no coincidence both were nearly driven to extinction—they killed them to starve Native people pic.twitter.com/bclCTwbsUR
A core element of Denver Water’s mission is ensuring the large, complex system that collects, cleans and delivers drinking water for 1.5 million people is prepared to meet future challenges.
And with more than 100 years of operations under its belt, Colorado’s largest water provider, which serves about 25% of Colorado’s population, is in the biggest period of capital investment in its history. Denver Water expects to invest about $1.7 billion into the system during the next 10 years.
“The work we do provides the critical water supply that the community we serve needs to thrive and grow,” said Denver Water CEO/Manager Alan Salazar.
“Continuing to maintain and invest in the system that supports our water supply will ensure that we — Denver Water as well as our customers — are ready for what lies ahead, from a warming climate to the potential for new regulations, while keeping rates as low as good service will allow,” Salazar said.
Since 2022, Denver Water has replaced an average of 97,000 feet of water mains per year. Photo credit: Denver Water.
Responsibility to maintain and protect the state’s largest water system, along with a desire to encourage water conservation, keep essential indoor water use affordable and ensure the utility is financially stable, were incorporated into the Oct. 22 decision by Denver’s Board of Water Commissioners to approve new water rates for 2026.
Denver Water is protecting and preparing the complex system and its customers for the future in many ways, including:
The Lead Reduction Program, which started in 2020, is protecting customers from the risk of lead in their drinking water and to date has replaced more than 35,000 old, customer-owned lead service lines at no direct cost to customers.
The new Northwater Treatment Plant, which began operations in 2024, can clean up to 75 million gallons of water per day and can be expanded when needed to 150 million gallons per day.
The Gross Reservoir Expansion Project, which began construction in 2022, is designed to nearly triple the reservoir’s storage capacity.
The Landscape Transformation Program, which helps customers remodel landscapes dominated by water-intensive Kentucky bluegrass into water-wise, climate-resilient ColoradoScapes.
And ongoing work to replace aging water mains, upgrade infrastructure on the utility’s southern collection and treatment system, and reach a net-zero carbon emissions goal by 2030.
Overall, Denver Water expects to invest $1.7 billion over the next 10 years in projects that will maintain, repair, protect and upgrade the system, and make it more resilient and flexible in the future.
In addition to rates paid by customers, funding for Denver Water’s infrastructure projects, day-to-day operations and emergency expenses like water main breaks comes from bond sales, cash reserves, hydropower sales, grants, federal funding and fees paid when new homes and buildings are connected to the system.
The utility does not receive tax dollars or make a profit. It reinvests money from customer water bills and fees to maintain and upgrade the water system.
And the utility is committed to delivering a safe, clean and affordable water supply to its customers while managing the impacts of the larger economy, from inflation to supply chain issues.
How the 2026 water rates will affect individual customer bills will vary depending on where the customer lives (either in Denver or in one of the utility’s suburban distributor districts) and how much water they use.
And major credit rating agencies recently confirmed Denver Water’s triple-A credit rating, the highest possible, citing the utility’s track record of strong financial management.
Monthly bills for single-family residential customers are comprised of two factors: a fixed charge, which helps ensure Denver Water has a more stable revenue stream to continue the necessary water system upgrades to ensure reliable water service, and a volume rate for the amount of water used.
Combining both of those factors, a typical single-family residential customer who uses 104,000 gallons of water annually will see their monthly bill increase by an average of $2.45 to $3.30 over the course of the year, depending on where the customer lives (in Denver or in one of the utility’s suburban distributor districts) and the type of service the customer’s suburban distributor district receives from Denver Water.
(See the infographic below for information about Denver Water’s suburban distributor districts, types of service and rates.)
The monthly bill example above includes an increase to the fixed monthly charge, which is tied to the size of the meter. For most single-family residential customers with a 3/4-inch meter, the fixed charge will increase by $1.85 in 2026, to $20.91 per month.
The more you use, the more you pay
After the fixed monthly charge, Denver Water’s rate structure for residential single-family customers has three tiers based on the amount of water used. The tiers are designed to keep essential indoor water use affordable while encouraging water conservation outdoors. (See additional details about the 2026 rates for the three tiers in the infographic below.)
The first tier is charged at the lowest rate and covers essential indoor water use for bathing, cooking and flushing toilets. Each customer has their individual first tier determined by the average of their monthly water use as listed on bills that arrive in January, February and March — when there is very little or no outdoor watering.
The second tier is for water consumption, typically used for outdoor watering, that is above the customer’s first tier and up to 15,000 gallons of water per month. Water use in this tier is considered to be an efficient use of water outdoors.
The third tier is for water use of more than 15,000 gallons per month. It is priced at the highest level to signal potentially excessive water use and encourage conservation efforts by larger-lot customers.
Bills in the summer months can be higher if customers use water to irrigate their outdoor landscapes.
Need help?
Denver Water offers one-time payment assistance to customers who may qualify. The utility’s Customer Care representatives also can help customers navigate payment options and unique circumstances. Customers can reach them via denverwater.org/ContactForm or by calling 303-893-2444.
What customers can do to save water, money
Denver Water encourages all customers to conserve water where they can indoors and out.
Finding and plugging leaks inside the home can be done year-round, and the utility offers rebates for qualified water-saving toilets and sprinkler equipment.
To help customers remodel their lawns to create a more vibrant, diverse ColoradoScape, Denver Water in 2026 will again offer a limited number of customer discounts on Resource Central’s popular turf removal service and its water-wise Garden In A Box plant-by-number kits. Photo credit: Denver Water.
Outside, Denver Water encourages customers to conserve water by remodeling unused areas of water-intensive Kentucky bluegrass into more diverse, water-wise ColoradoScapes that fit naturally into our dry climate and are interesting to look at through all seasons. These drought-resistant and climate-resilient ColoradoScapes include tree canopies and plants that help maintain vibrant urban landscapes and benefit our communities, wildlife and the environment.
Using less water also means more water can be kept in the mountain reservoirs, rivers and streams that fish live in and Coloradans enjoy. It also can lower monthly water bills, saving money.
Note 1: An individual customer’s monthly water bill will vary depending on where they live in Denver Water’s service area (in Denver or in one of the utility’s suburban distributor districts), the types of service the suburban distributor district receives from Denver Water, and how much water the customer uses.
Note 2: The difference in volume rates (in the infographic above) for Denver Water customers who live inside Denver compared to those who live in the suburbs is due to the Denver City Charter (see Operating Rules), which allows permanent leases of water to suburban water districts based on two conditions: 1) there always would be an adequate supply for the citizens of Denver, and 2) suburban customers pay the full cost of service, plus an additional amount.
