Since April’s Board meeting, hydrological conditions across the Colorado River Basin have continued to deteriorate sharply, according to River District Director of Science and Interstate Matters Dave Kanzer. He explained that the hot, dry months of early summer accelerated the effects of the 21-year ongoing drought and turned a number of worst-case scenarios into reality more quickly than expected.
“The antecedent conditions of low soil-moisture content, a snowpack which melted early, and low seasonal precipitation really added a lot of stress to the system right off the bat,” Kanzer stated.
Peak snowpacks occurred weeks earlier than previously seen and nearly all were below average. The Gunnison Basin snowpack, for example, peaked March 27 at 90% of average, while the Roaring Fork River watershed peaked April 1 at 95% of average. Add to that a record dry April and May, streamflow in most West Slope watersheds plummeted to historic lows while water temperatures skyrocketed as ambient air temperatures broke records across the state in June and July, resulting in fish-kill events on the Upper Colorado near Kremmling in late June.
On July 1, Colorado Governor Jared Polis signed a Drought Emergency Declaration, identifying extreme or exceptional drought conditions across all the counties within Colorado River District boundaries.
In their report to the River District board, Kanzer and Don Meyer, Senior Water Resources Engineer, described forecasts for the Yampa and White River basins at less than 30% of average. Monsoonal rains aided low streamflow in the Yampa, but the River District and the Division of Water Resources have since coordinated releases from Elkhead Reservoir to postpone a Yampa River call.
While the White River had a slightly better spring rainfall total, ranchers and farmers within the basin struggled in mid-summer to secure enough water to finish crops.
Further downstream, Lake Powell officially dropped to its lowest level since originally filled, reaching only 32% of its active capacity. So far in Water Year 2021, outflows from Glen Canyon Dam have been 3.6 mAF more than inflows. Because of concerns that Lake Powell will drop below 3,525’, the Bureau of Reclamation began to implement the Drought Response Operations Agreement (DROA). Agreed upon by the Upper Basin states as one of three steps in the Drought Contingency Plan (DCP), DROA was not expected to come into play for another few years at least. In order to allow Lake Powell to safely continue its hydropower operations (a process compromised below 3,490’), Upper Basin states will begin releasing water from Colorado River Basin Storage Project.
Over the next three months, Flaming Gorge, Blue Mesa, and Navajo Reservoir will send approximately 181 kAF to raise the level of Lake Powell by approximately three feet. Blue Mesa is expected to drop by eight feet.
“Overall, hydrological conditions across the Colorado River District are poor,” Kanzer and Meyer concluded.
A Northwest Colorado Drought Tour is planned this August with State officials including Governor Polis, legislators, and local stakeholders to highlight on-the-ground drought responses and enhance communication between decision makers and local community leaders. The Colorado River District is participating and will provide updates to constituents during and after the events of the tour.