The Groundwater in the West is being Used Up

From Castle et.al.

A new study released last week by scientists at NASA Goddard Space Flight Center and University of California at Irvine has found that groundwater storage within the Colorado River Basin has been depleted by 41 million acre feet since late 2004. Most of the depletion has come since 2010 as the region endures an extended drought. This study is the first to quantify the amount groundwater used in the seven western states of the Colorado River Compact. According to the U.S. Bureau of Reclamation, the federal water management agency, the basin has been suffering from prolonged, severe drought since 2000 and has experienced the driest 14-year period in the last hundred years.

Observing the groundwater buried beneath layers of soil and rock was almost impossible until, the twin satellites known as the Gravity Recovery and Climate Experiment, or GRACE, were launched in March 2002. At the time few believed the satellites could measure changes in groundwater, but thanks to work of Dr. Jay (James S.) Famiglietti and his graduate student (at the time) Matt Rodell, who were then working at the University of Texas at Austin the techniques for measuring groundwater using the GRACE satellites were developed and proven. Expanding on that work is this new paper by Stephanie L. Castle, Brian F. Thomas, John T. Reager, Matthew Rodell, Sean C. Swenson, and James S. Famiglietti.

While the need to use groundwater resources to meet Basin water demands has long been recognized, the quantity of available groundwater and the sustainable rate of groundwater use are not known. As the drought in the western states has persisted for most of this century, water management under drought conditions has focused only on surface water resources- the flow of the Colorado, the levels in Lake Mead and Lake Powell. There is neither enough data nor a regulatory framework to fully manage groundwater. However, as this study shows us, by only managing the water withdrawals from the reservoirs (Lake Mead and Lake Powell) water use may not have been reduced at all, but instead groundwater may have made up more of the shortfall in water.

From Castle e.t al.

The study found that the Colorado River Basin lost almost 53 million acre feet of water over the study period with 12 million acre feet coming from the falling level in the two reservoirs and the remaining 41 million acre feet being pumped out from groundwater. The scientists estimated changes in groundwater storage during the 9-year drought period, when reservoir volumes were intensively managed to maintain hydropower production, maintain water levels above the public supply water intake pumps, and to meet surface water allocations to the Basin states using the methods developed by Drs. Jay Famiglietti and Matt Rodell.

The total water storage in a region as seen by the satellites is comprised of soil moisture, snow water equivalent, surface water (including river flow and reservoirs), and groundwater. Accessible water is assumed to be surface water reservoir storage and groundwater storage. They assumed Lakes Mead and Powell accounted for the majority of the observed surface water change as they comprise approximately four times the annual flow of the river and make up 85% of surface water in the Basin at any time. So the flow of the river was ignored introducing an error of 5%-15%. USGS and ADWR monitoring wells in the Colorado Basin showed good agreement with the GRACE-based estimates further confirming the methodology.

A brief recovery in groundwater storage was observed in the data from June 2009-March 2010, when moderately wetter conditions provided a combination of potential groundwater recharge and temporarily alleviated the need to augment surface water supplies, but the overall observed trend is not good. As the Bureau of Reclamation more tightly controlled and limited surface withdrawals, groundwater reserves were tapped to make up the loss, demonstrating the close connection between surface water availability and groundwater use. As available water in the west has been diminished by an extended drought and demand for water has actually increased over these years, solely managing surface water in the Colorado Basin, without regard to groundwater loss, has resulted in the 41 million acre foot reduction in ground water reserves which predominately occurred from April 2010 to November 2013.

Groundwater is typically used to augment the limited surface water supplies in the arid, Lower Colorado Basin and across the entire Basin during drought. Groundwater represents the largest supply of water for irrigation within the Basin and against all reason irrigated acreage in the Colorado Basin increased during the study period. Furthermore, according to Drs. Famiglietti and Rodell, the prolonged drought across the southwestern region of the United States has resulted in overreliance on groundwater by public water to minimize impacts of the drought on public water supply. The decrease of an average of 4.5 million acre feet of groundwater each year may merely reflect the problems with the Colorado River Compact, the regulatory framework already in place to manage surface waters. The Compact which allocates the flow of the Colorado River to Colorado, Utah, Wyoming, New Mexico, Arizona, Nevada and California and through a 1944 treaty to Mexico promised what turned out to be more than 100% of the water available at the time and the current researchers believe that the over allocation of the Colorado River’s water was 30% during the study period based on the groundwater loss of 4.5 million acre feet a year from the groundwater reserves.

Specifically, the amount of water allocated under the Colorado Compact was based on an expectation that the river's average flow was 16.5 million acre feet per year. According to the University of Arizona, a better estimate would have been 13.2 million acre feet at the time of the Colorado Compact and the records going back to Paleolithic times (more than 10,000 years ago) indicates periods of mega-droughts in the distant past and climate forecasts for the future are dire. The political hurdles the Colorado River Compact may need to be renegotiated and include groundwater resources. During the drought of 2001-2006 the Colorado River flow was estimated at 11 million acre feet and hit a low of 6 million acre feet in 2002. The situation was critical bordering on regional rationing when the drought ended.

More than 23 million people of the lower basin are at least partially dependent upon the water resources of the Colorado River. Almost 74% of them reside in the greater Los Angeles and San Diego areas. The current drought in California has only emphasized the need for more active and enforceable groundwater management throughout the Basin, in particular, during drought. During the study period the scientists observed that groundwater is already being used to fill the gap between Basin demands and the annual, renewable surface water supply.

Managing groundwater is a daunting task. Even today groundwater sustainability is still not fully understood. In addition, there are droughts, climate changes; water draws from surface water changes the recharge rate of the groundwater. The U.S. Geological Survey did not begin quantitative analysis of the major groundwater systems of the United States until 1978 and since that time there has been tremendous evolution in the understanding of and ability to model groundwater systems. Before the groundwater basin is irreparably overdrawn, we need to understand what sustainable water use in the region is and embrace it. Otherwise the groundwater will be pumped until it is gone.

See the excellent blog post by Jay Famiglietti

Bringing the Colorado River Delta Back to Life

from NASA the Colorado Delta in 2004

Yesterday, March 23rd , the Morelos Dam along the US–Mexico border near Yuma, Arizona, opened their gates and began releasing 34,000,000,000 gallons of water downstream that will make up an eight-week long pulse of water intended to mimic a spring flood. Since 1960, when Glen Canyon Dam was finished, the Colorado River has rarely flowed to the sea, and the river’s delta a once alive estuary started to fade and dry out. Now, scientists, environmentalists and politicians are trying to bring the Colorado River Delta back to life.

The water that will make up this pulse was slowly collected from releases from the Hoover, Davis and Parker dams removing some water from the parched west during this extended drought. The water has collect behind the most southerly dam on the river, the Morelos, which sits on the Mexico-US border and normally diverts the last of the Colorado toward agricultural lands in Mexico. The demand for the water of the Colorado has increased and yet the flow (except in the years of the El Niño rains) has not met the demand. Part of the problem has been lack of adequate water management and conservation, but that is only part of the problem.

Control of the water and flow of the Colorado River is part of a 1944 Treaty between the United States and Mexico. The United States and Mexico have spent years negotiating a new Colorado River agreement between the two nations changing the allocation of water. The agreement, called Minute 319, requires the US to provide $21 million to help improve water-saving measures in Mexico (for example lining irrigation canals) and the United States to forego some of its water rights this year to free up water for the pulse and to guarantee a minimum flow to the delta for environmental purposes.

The Minute 319 agreement changes the framework of water law that has always been “First in time, first in rights.” Now the U.S. and Mexico will share the surplus when and if water is plentiful and share shortage when water is scarce. The agreement also commits the two nations to work together on water conservation and restoration of the long dried out delta estuary by guaranteeing a small continuous flow, totaling an additional 16,000,000,000 gallons to the delta to sustain it over the next three years. It's a small but continuous trickle that researchers expect will bring a portion of the delta back to life in the weeks after the pulse.

The Colorado River delta like all estuaries is an incredibly complex ecosystem that we are only beginning to understand. Estuaries are productive ecosystems and habitats. The type of habitat is determined by geology, salinity and climate. Estuaries are fragile ecosystems that are very susceptible to disturbances both natural and those created by man. By diverting the flow of the Colorado River fresh water flow for irrigation and drinking water supplies changes flow, quantity of fresh water if any entering the estuary, and impacts the balance within the ecology. As the ecosystem of estuaries declines, species die out, coastlines experience excessive erosion by wind and tidal action. It is going to take knowledge, effort and resources (wealth in all forms but especially water rights) to restore the delta.

Here in the Chesapeake bay watershed we have reached the point in population density and development that during times of drought, natural flows on the Potomac are not always sufficient to allow water withdrawals by the utilities (including power generation which takes an awesome amount of water) while still maintaining a minimum flow in the river for sustaining aquatic resources. For more than two centuries the waters of the Potomac seemed unlimited so that our region is not hampered and tied by water allocation agreements created almost a century ago that bind the waters of the Colorado River to fixed and rigid allocations. Instead, the Interstate Commission on the Potomac River Basin, ICPRB, allocates and manages water resources of the river to improve reliability of the water supply and ensured maintenance of in-stream flows to meet minimum aquatic habitat requirements.

It is unknown if this can be accomplished for the Colorado River whose management is complicated by interstate boarders, water rights that have a basis in law and are truly a form of wealth, but cannot be fairly monetized, sold, or transferred without addressing water and groundwater law in the west. In the third year of drought in California when Governor Jerry Brown has declared a drought emergency and stopped all the water allocations from the State Water Project, which delivers water from Northern California through the California Delta to Central valley Farmers the Imperial Valley, east of Los Angeles, still has plenty of water.

The farmers there are unaffected by the drought. The Imperial Valley is not connected to the State Water Project; its water comes directly from the Colorado River, which has continued allocations despite the need for the water for the Minute 319 agreement. The Imperial Valley’s share of water is assured by the terms of the 1922 Colorado River Compact and subsequent agreements among the seven states that depend on the Colorado River water for life. The Imperial Valley farmers were the first to tap the Colorado for irrigation water and in in water law in the western states, one rule is supreme: "First in time, first in right."

The framework of the Minute 319 agreement to water management changes that absolute. While it creates benefits for water users on both sides of the border, demonstrating that with a broad approach to river and water management, there is room to negotiate and serve multiple interests. It is also a model that would take water and what is truly wealth from the Imperial Valley farmers if applied elsewhere in the Colorado River basin. Water, water rights, environmental needs are complicated in the west and not only impact the wealth of the farmers, but the cost of food. Cheap water and fuel mean cheap food. A century ago food accounted for about a fifth of the household budget of the typical U. S. citizen, now it is about 3%, though only a few years ago it was under 2%.

As part of the changes that are coming in the allocations of the Colorado River waters, water rights must be fairly monetized so that they can be bought and sold to allow future agreements elsewhere on the Colorado to be a win for all stakeholders not just those parties who advocate the restoration of the delta’s environment and the Colorado River itself, but to include the holders of the water rights and the U.S. consumer.