We are living in a megadrought.
A study of tree rings revealed that this phenomenon has occurred naturally in the West four previous times since the year 800. Only one was drier over 19 years than 2000 to 2018. One of the megadroughts, in the late 1200s, prompted the Ancestral Puebloans to abandon the Four Corners.
Although these earlier events resulted from natural climate variability, climate change has deepened the current megadrought. Unfortunately, climate models unequivocally project that our region will continue to warm more than the global average, as it has in recent decades. Warmer temperatures ensure that more precipitation will come as rain, snowmelt will come earlier and greater evaporation will dry the landscape.
How will we adapt? Answers at the regional and state levels will constrain what happens locally.
Regional responses rest on the 1922 Colorado River Compact and associated agreements, including the 2019 Drought Contingency Plan. These painstakingly negotiated documents sought fair distribution of the river’s precious resource that now serves 40 million people and 3.5 million acres of cropland in seven states and Mexico. The pacts embody the principle of Prior Appropriation (“First in use, first in right”) that has governed water allocations across the West for 150 years.
The 2019 plan recently led to the first ever curtailment of water withdrawals from the Colorado River, initially affecting Arizona and Nevada. It also led to mandated releases of water from upstream reservoirs, including Navajo Lake, to ensure maintenance of Lake Powell water levels. In turn, Lake Powell releases water allocated for the Lower Basin states – Arizona, Nevada and California.
Continued maintenance of Lake Powell water levels likely will require enhanced conservation by the Upper Basin states – Wyoming, Colorado, Utah and New Mexico – for which Colorado’s share is about 50%. The 2015 Colorado Water Plan, developed with broad stakeholder input, guides statewide conservation planning and initiatives. It seeks to replace the increasing purchases of agricultural water rights to serve municipal and industry needs (“buy and dry”) with demand management, using “voluntary, temporary and compensated” water-right leasing. To date, the plan has led the state to invest nearly $500 million in conservation and policy experiments, but not yet to decisions about a specific demand-management mechanism.
Facilitating local adaptation, recent projects have created storage capacity in Lake Nighthorse and in the Long Hollow Reservoir. The latter ensures delivery of La Plata River basin water to New Mexico under a bilateral agreement, allowing more withdrawals for Dryside irrigation. Lake Nighthorse is already beginning to serve the Lake Durango and La Plata West water districts. Deliveries to the city of Durango and La Plata Archuleta Water District await construction of new pipeline to the east. This pipeline project is the most important drought adaptation action available to serve city and county residents.
The other major drought-related risk in our region is wildfire. An associated adaptation initiative is more actively managing local forests to reduce wildfire risk and to protect water supplies. As part of a larger regional effort, the city of Durango, La Plata County and Durango Fire Protection District are funding fire mitigation in the city’s open space and beyond.
The megadrought brings many uncertainties. How long will it last? Could it lead to a major wildfire that would again slow the economy? Could impacts here slow the flow of new residents? Or prompt current residents to imitate the Ancestral Puebloans and move elsewhere?
What is certain is that aridity will increase across the Southwest and that the community must adapt to the changing conditions through negotiation and cooperation among local stakeholders.
It is a truism that human beings rise to meet crises. Our task is to do exactly that.
