Here’s an in-depth look at the Lower Colorado River Basin’s intentionally created surplus accounts in Lake Mead from Brett Walton, that’s running in Circle of Blue. Click through and read the whole thing. Here’s an excerpt:
This year and next, Arizona and California intend to draw on water they banked in the big reservoir, even as water levels drop.
A complex and arcane water banking program in the lower Colorado River basin, adopted in 2007 and later amended, was designed to incentivize water conservation, prevent waste, and boost storage in a waning Lake Mead.
The program has already proved its worth, lifting Lake Mead dozens of feet higher than it otherwise would have been and nurturing collaboration among states that will need to work together to surmount daunting challenges of water availability. In the next two years, the program will be tested in another way, becoming a small but important source of water for Arizona and California even as the lake continues to fall to levels that haven’t been witnessed in several generations.
Water managers in the basin view the program, called intentionally created surplus or ICS, as a flexible tool for adapting to a drying climate. It is a tool that they will soon call upon. Bill Hasencamp from the Metropolitan Water District of Southern California, a large regional wholesaler, told Circle of Blue that the district intends to draw between 100,000 and 150,000 acre-feet from its savings this year.
Arizona officials, meanwhile, plan to use 69,100 acre-feet of ICS credits to reduce mandatory cutbacks that will be required in 2022 if Mead declines as projected. The state already used this maneuver to deal with a cutback last year, albeit in a smaller amount. Instead of taking a big cut in one year, ICS allows Arizona to “smooth the reduction,” as Chuck Cullom of the Central Arizona Project put it. CAP delivers the bulk of Arizona’s Colorado River allocation and is first in line in the state when cutbacks are required.
These amounts are small but significant, especially in these times. An acre-foot is 325,851 gallons, or the amount of water that will flood an acre of land to a depth of one foot. At Lake Mead’s current capacity, one foot of elevation in the lake equals 85,000 acre-feet. These ICS uses, at the high end, amount to two and a half feet of elevation in Lake Mead.
At the same time that water users plan to tap their savings, scholars in the basin are calling for more analysis of the ICS program, especially as Lake Mead’s decline accelerates. They would like to check how the system responds to ICS use under a range of water supply scenarios.
Ever since the mid-2000s, the last time that water supplies in Colorado River reservoirs reached critically low levels, the biggest water users in Arizona, California, and Nevada have been stashing water in Lake Mead, in preparation for another emergency to come — and in an attempt to avoid a catastrophic collapse of the region’s water storage system.
With the federal government now projecting that Lake Mead will drop precipitously in the next two years — perhaps to levels not seen since the Great Depression, when the country’s largest reservoir was first filled — that emergency has arrived.
“While Colorado River water users have invested billions of dollars to reduce consumption and increase resiliency, the situation we face today is real and urgent,” John Entsminger, the general manager of the Southern Nevada Water Authority, said at a House Natural Resources subcommittee hearing on May 25…
Because of record-high temperatures and a drying climate, the basin is also dangerously parched. Thirsty soils gulp melting snow before it reaches streams. Lake Mead, which is just 36 percent full, is in poor health. So is Lake Powell, located upstream and only 34 percent full.
ICS was conceived during negotiations between the seven states that led to a milestone agreement in 2007 that transformed how the basin operates. At the time, Lake Powell had experienced the driest five-year period in the region in a century and there were unresolved questions about delivering water under such conditions. The 2007 Interim Guidelines, which expire at the end of 2025, were a landmark document that secured three substantial changes.
First, the guidelines developed a formula for determining how much water is released from Lake Powell into Lake Mead. The releases are designed to keep the reservoirs roughly in balance.
The guidelines also set Lake Mead elevations at which lower basin states would be required to reduce their withdrawals. The first of these shortage tiers — at 1,075 feet above sea level — is expected to be breached next year. (Mead is currently at 1,073 feet, but for shortage determinations, it is the projected level in the following January that matters. Right now that projection is 1,066 feet.)
The third change was establishing intentionally created surplus, or ICS. The program allows big water users in the lower basin to open a savings account in the lake. To bank water in their account, they must take an action that reduces water consumption. That banked water is credited to the user that created it. ICS is not conservation in the household sense of simply using less. It is not taking a shorter shower or only watering the lawn once a week. ICS is instead more comparable to a personal savings account. Water banked now becomes an asset that can be withdrawn later, subject to certain conditions…
With a bit of linguistic maneuvering, the rules were written so that agencies like Met could create “surplus” by investing in conservation. Say, for example, that Met paid to line a canal with concrete so water would not seep into the soil, or paid farmers to fallow their fields. The Bureau of Reclamation, playing the oversight role in the lower basin, checks that the lining kept water in the canal and the alfalfa fields were not irrigated. That amount of water — the difference between what would have been delivered without the intervention and what was actually delivered — would then be credited to Met in the form of ICS, minus a small percentage that is the lake’s share.
A few years later these rules were altered to bring Mexico into the program. U.S. entities can pay a counterpart in Mexico for conservation and reap the ICS asset. The rules were changed again in 2019, in an agreement called the Drought Contingency Plan, or DCP, that welcomed certain tribal nations into the fold. Banked water is now subjected to a one-time tax of 10 percent, a cut that is credited to the storage system as a whole.
Only six entities have created ICS, according to Jeremy Dodds, who is responsible for ICS accounting and verification at the Bureau of Reclamation. Those six are some of the largest water users in the basin: Met, Gila River Indian Community, Colorado River Indian Tribes, Southern Nevada Water Authority, Imperial Irrigation District, and the Central Arizona Water Conservation District, which manages CAP. Within the four categories of ICS, there are limits on the ICS each water user can create, the amount they can take out in a year, and the total amount stored.