Colorado River annual flows are over-allocated among seven states, and reservoir storage in Lakes Powell and Mead is shrinking. Hence, water allocations under the 1922 Colorado River Compact may be renegotiated or litigated in coming years. Nevada needs to aggressively protect its interests in the Colorado River waters that supply 90 percent of Clark County’s needs.
More interstate water rights have been allocated by the “Law of the River” (rules, regulations and laws, including the Compact, governing the Colorado River) than there is real water on a reliable, continuous basis to satisfy them. Fortunately, not all those water rights are currently in continuous use, especially in the Upper Colorado Basin, leaving some margin, which is rapidly diminishing with population growth and new development.
The Compact and a treaty with Mexico have allocated 16.5-million allocated acre-feet. The problem is that tree-ring analyses suggest that the actual yearly flow over the last 1,200 years has been 14.6-million acre-feet. And we’re currently in a long-term drought.
Fortunately, Lakes Mead and Powell reservoirs can hold a combined 56-million acre-feet. But diversions and increased evaporation due to a Colorado River Basin drought since 2000 have reduced water levels in them to less than half their capacity. And Upper Basin states, especially Colorado, Utah and Wyoming, are beginning to use more of their allocations.
The Southern Nevada Water Authority (SNWA) has asked the Legislature to outlaw water-guzzling ornamental grass that people almost never walk on (“non-functional turf” in road medians, housing developments and office parks). This unprecedented measure would reduce annual water use by 15 percent, allowing for some growth while remaining below use limits dictated by the Law of the River or falling Lake Mead water levels.
These savings would buy time to develop new conservation measures, perhaps greater Colorado River allocations, and even restoration of Lake Mead water storage to historic levels.
Clark County’s bedroom communities have embraced conservation measures, including aggressive monitoring of sprinklers and leaky irrigation systems. Since 2003, SNWA has prohibited developers from planting green front lawns in new subdivisions. It also offers owners of existing properties very generous rebates up to $3 per square foot to tear out sod.
But 2020 was among our driest years in history, when Las Vegas suffered a record 240 days without measurable rainfall. Although a ban on ornamental grass may draw resistance from master-planned communities, officials believe homebuyers from wetter regions now accept such limitations.
Clark County water-saving measures such as new conservation, plus greater river allocations and revived lake storage would greatly diminish the pressures to drain water from aquifers, streams and other surface waters to the north. North-to-south water diversion would unnecessarily raise serious policy issues,0 extensive and expensive litigation and uncertainty.
That would cause unacceptable damage to rural county resources, business and communities.
Federal projections for Lakes Mead and Powell water levels show them dropping to historic low levels in coming months that may cause the U.S. Bureau of Reclamation to declare an official shortage in 2022 for the first time. Adverse developments could cause renewed pressure on northern water sources. Such problems may also reduce the levels of very inexpensive hydropower available to Nevada, raising electric rates.
Compounding the problem for Northern Nevada, the state and the Sierra Mountains currently face “extreme or exceptional” drought conditions.
If Clark County renews past efforts to raid Northern Nevada water, the State government would become entangled in a bitter and protracted interregional battle because water rights in Nevada ultimately belong to the State and are appropriated to users based on the Prior Appropriation Doctrine. Here too, the problem is that more water has been appropriated than actually exists.
However, here too, water usage is not continuous at full rights levels, and so the problems have been limited. But increasing use in the North and new claims from the South could precipitate serious issues.
There are experiments on water rights going on in the North, but they are as yet unsettled. And existing litigation in the North is expected to continue for at least half-a-dozen years. Hence, north-to-south flow is not a practical option.
Ron Knecht, a Nevada Policy Research Institute Senior Policy Fellow, has served Nevadans as State Controller, a higher education Regent, economist, college teacher and legislator. Contact him at RonKnecht@aol.com.