Hydrological Bounty Before a Dry Summer
Just when you think you know what to expect, the opposite occurs.
With Water Year 2023 almost complete, the surprises keep coming. Instead of hot, dry and dusty conditions associated with the early days of summer, rain, hail, snow, reservoir spills, and above average river flows continued with late peak flows and localized flooding across the state of Colorado and in the Upper Colorado River Basin. Yet, the apparent delay in the arrival of monsoon season will impact these conditions going forward.
“There is no drought in Colorado today,” said Kanzer on July 18. “It’s really an amazing recovery. A year ago, almost 100% of the state was in drought.”
NOTE – As of Thursday, July 27, the Colorado Drought Monitor published a new map in which areas of southwest Colorado are now in the “Abnormally Dry” or “Moderate Drought” categories.
Local Reservoirs See Recovery
As of July 20, Blue Mesa was nearly full and had to spill to make room for the inflows. The well-above average snowpack of last winter along with higher-than-expected runoff season in the Gunnison Basin brought the nearly 900 acre-feet reservoir back to life in just one year. For context, the last time that Blue Mesa was at a historical low, it took more than three years to refill.
Don Meyer, Senior Water Resources Engineer, shared updates from other local storage operations and the current hydrology for the West Slope.
Those stories told the impacts of a delayed, prolonged runoff across all West Slope basins.
“Later spills created late season peaks which really benefited the river,” said Meyer. “In the Roaring Fork River, the timing of the Twin Lakes spill allowed for one of the latest seasons peaks.”
A well-watered East Slope and Front Range meant that trans-basin diversions were paused or delayed, offering benefits for the flushing flows supporting healthy ecology for fish and riparian wildlife.
Rivers across the Western Slope are on their way down now, however, and the historic heat index means that the state will likely see a quick return to more widespread drought conditions and fire concerns.
Colorado River Basin
Looking downstream to the broader Colorado River Basin, water storage is experiencing a similar rebound.
“Lakes Powell and Mead have also had significant gains, even if they did not fill and spill,” Kanzer explained.
Kanzer went on to say that with 144% of average inflows to Lake Powell for Water Year 2023, the reservoir is now at its seasonal high and will be declining. The next 24-month study, to be published by the Bureau of Reclamation in August, will determine which ‘tier’ the reservoir levels fall into and how much water will be released out of Powell.
But forecasts and recent temperature spikes across the Colorado River Basin have water managers still on edge when it comes to considering long-term plans.
“For this year’s average global temperature, we’ve never seen it this hot,” said Kanzer. “Phoenix is seeing 20 straight days of 100 plus degrees fahrenheight.”
The continued unpredictability of these conditions, paired with the volatility of the weather events, only underscore the importance of management practices which are built to withstand uncertainty and extremes.