Wednesday, March 8, 2023

Even with the Rains the Colorado River is still in Trouble

Over one hundred years ago the Colorado Compact apportioned the water of the Colorado River amongst the seven compact states (Colorado, Utah, Wyoming, New Mexico, Arizona, California, Nevada) and Mexico. 1922 Colorado River Compact allotted the Colorado’s water on the basis of territory rather than prior appropriation. Before this agreement was negotiated ownership of water rights was based on historic use, first to use the water owned it in perpetuity.  California was growing so fast the other territories feared they would appropriate all the water preventing their territories from ever being able to grow. The allocation of water rights based on territory allowed development to proceed in the lower basin (essentially California at that time) while safeguarding supplies for the upper basin. Then, as now, California's growth and demand for water was viewed with concern by her neighbors. To this day California still has the most senior water rights; however, the historic allocation of water rights is being questioned due to the growing water crisis.

Lake Meade 2000-2022 from NASA

The amount of water allocated under the Colorado Compact was based on the belief that the river's average flow was 16.5 million acre feet per year. The upper Colorado River was allocated 7.5-million-acre feet to the upper basin (Colorado, Utah, Wyoming, New Mexico), the lower basin Colorado River (Arizona, California and Nevada) were allotted 7.5-million-acre feet and Mexico was allotted 1.5-million-acre feet.

From the start there was a problem; they over allocated the Colorado River.  According to the University of Arizona, a better estimate would have been 13.2-million-acre feet at the time of the Colorado Compact.  Once the flow of the Colorado exceeded needs, but this is no longer true. Use of the river has increased tremendously over the last century. While over the same period of time, the flow from the Colorado River has fallen attributed to changing land use and changing climate. From 2000 through 2022, the river's annual flow averaged just over 12 million acre-feet; and in each of the past three years, the total flow was less than 10-million-acre feet.

The records going back to Paleolithic times (more than 10,000 years ago) indicates the region is subject to periods of mega-droughts in the distant past and climate forecasts for the future are dire. There has been a drought somewhere in the Colorado River Basin for the past 22 years. This combined with higher temperatures has led to what some are calling aridification of the region. The Colorado River and its watershed are in trouble, the states need to work together to come up with a sustainable use plan for the future.  

Population growth, increased food production and increased power production all consume more and more water. The water available from the Colorado River has decreased, not increased with the increased demand. Even without climate change more than 35 million people (in the upper and lower basins) now depend upon the Colorado River’s waters for their water supply. The need for water is always growing with population and wealth. Currently in the upper basin, 44% of Wyoming, 37% of Colorado, 89% of Utah, and 45% of New Mexico are in drought. In the lower basin 13% of Arizona, 83% of Nevada and 49% of California are in drought. This is actually is much improved over the summer. 

from the Lake Meade water database

California is the most populous state in the nation and Nevada is one of the fastest-growing states in the nation and their need for water has continued to grow. Despite aggressive conservation activities the region simply does not have enough water to meet the projected demand. Las Vegas was able to reduce water use by a third by the implementation of draconian conservation measures (removal of ornamental turf grass and utilization of low flow plumbing fixtures etc.). This was city and suburban consumption, not agricultural or power generation use of water which is much more difficult to cut and utilizes the largest share of water. Remember though, that agriculture use of water is to feed the growing number of people. Hydropower, is a significant source of power to the region.

Lake Meade sits on the Nevada-Arizona border and was created in 1935 by the construction of Hoover Dam. Lake Mead and the upstream Lake Powell are the major water storage facilities in the Colorado Compact system. Roughly 96% of Lake Mead's water comes from melted snow in the upper Colorado River basin states.  The Compact states have not delt with the fact that the allotted water in the basin exceeds the average long-term (1906 through 2018) historical natural flow by a considerable amount. To date, the imbalance has been managed by slowly using up the considerable amount of reservoir storage capacity in the Colorado River system- Lake Powell and Lake Mead once held approximately 60 million acre-feet.

When built, it was assumed that drought years would be followed by wet year to refill the reservoirs. That has not happened recently, the last time the reservoirs filled was 1983. Instead, the reservoirs have been used to hide the fact that use of water exceeds average river flow and delay finding a long term sustainable solution. This cannot continue. The reservoirs (Lake Meade and Lake Powell) have dwindled to their lowest levels recorded and are nearing dead pool state when water can no longer be drawn out. Dead pool levels mean the dam can no longer release water downstream or generate power. 

The true existential crisis for the areas that depend on the water from the Colorado River looms just over the horizon. For without water there is no life. The states of the Colorado Compact need more water. Overuse is killing the Colorado water basin which suffers from decimated aquatic ecosystems, overdrawn and irreparably damaged groundwater aquifers, and polluted agricultural and urban runoff.

Water releases down river from Lake Meade and Lake Powell reservoirs are determined by the Bureau of Reclamation. Each year they forecast reservoir water elevations. Plans that were developed over the past two decades lay out detailed operational rules for these Colorado River reservoirs. The Bureau of Reclamation asked the states to voluntarily cut usage by 2 to 4 million acre-feet in response to the ongoing drought and historically low water levels in Lake Mead and Lake Powell reservoirs. 

However, the cuts in water usage proposed by the states are nowhere near enough to stop the falling water levels in the reservoirs. California’s water rights are considered senior and California interprets the law to mean Arizona should cut its supply before California. The Upper Basin states have said the Lower Basin states should receive the most cuts. All are afraid that emergency cuts will become permanent.

Last July drought operations were implemented to protect Lake Powell and the Bureau of Reclamation Since the states could not do it the Bureau of Reclamation is set to release a proposal on how to operate the Lake Powell and Lake Mead reservoirs and their adjacent dams (Glen Canyon and Hoover) in March, with the goal of finalizing it by mid-August.  Right now, they are in a stalemate until the water is rationed to overcome the political hurdles to renegotiate the Colorado Compact. California won’t give up its senior water rights and Colorado is attempting to dam tributaries to the Colorado River to hold all water they can in Colorado. It will have to reach complete crisis level before the states are ready to renegotiate the Colorado Compact and the winter rains and snow have rescued the situation for now.   

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