Groundwater Depletion in the Colorado River Basin

News Summary

A recent study from Arizona State University reveals alarming groundwater depletion within the Colorado River basin. Groundwater extraction now surpasses surface water depletion, with the basin losing approximately 27.8 million acre-feet of groundwater since 2003. This unsustainable trend poses critical challenges for water management, especially in Arizona, where agricultural demands are high and regulations are weak. The study highlights the urgent need for improved water management practices to address the groundwater crisis in the context of climate change.

Arizona – A recent study from Arizona State University has revealed alarming groundwater depletion within the Colorado River basin, indicating that the rate of groundwater extraction now surpasses the depletion of surface water from major reservoirs such as Lake Mead and Lake Powell.

Since 2003, the Colorado River Basin has experienced a dramatic loss of approximately 27.8 million acre-feet of groundwater, which is roughly equivalent to the total capacity of Lake Mead. This figure is more than double the volume of water that has been extracted from surface reservoirs within the same period, highlighting a critical and potentially unsustainable trend.

Over the past decade, groundwater depletion has accelerated significantly. Research demonstrates that the rate of loss in this timeframe has been three times greater than that observed in the previous decade. The findings utilize NASA satellite data that measures gravitational changes to estimate fluctuations in underground water supplies over time.

Key Findings of the Study

The most significant declines in groundwater were observed in the Lower Colorado River Basin, which encompasses regions of Arizona, California, and Nevada. Notably, Arizona has seen substantial groundwater reductions, which are largely unregulated, exacerbating the situation. Groundwater simulations conducted for the Phoenix area have raised predictions of potential complete depletion by the end of the century. However, such assertions are contested by the Arizona Department of Water Resources.

In 2023, an assessment indicated that approximately 4.9 million acre-feet of groundwater demand in Arizona would go unmet over the next century unless proactive measures are introduced. This forecast underscores a substantial mismatch between current water use and available resources.

Impact on Water Resources and Climate Change

The Colorado River serves as a vital water source for over 40 million people and supports considerable agricultural sectors. However, the river’s natural flow has decreased by 20% over the last century and is projected to decline by an additional 30% by mid-century, primarily due to the combined effects of climate change and prolonged drought conditions.

Groundwater now constitutes approximately 35% of Arizona’s overall water supply, with a significant portion allocated for agricultural use. In many rural areas, groundwater pumping occurs without appropriate regulation, deepening the crisis as communities increasingly rely on deeper wells for water access, resulting in ground subsidence and dry stream beds.

Agriculture accounts for about 80% of water usage in the Colorado River Basin, with water-intensive crops such as alfalfa consuming large quantities of available resources. This reliance on groundwater represents a concerning unsustainable pattern, given the limited natural replenishment of these underground supplies.

Call for Improved Water Management

The findings of the study point to the urgent need for enhanced management practices, particularly within agricultural sectors, to address the ongoing groundwater crisis. Groundwater is often described as a “savings account” for water, while surface supplies operate more like a “checking account,” indicating the instability of current extraction levels.

States in the lower basin, namely California, Arizona, and Nevada, are facing escalating risks from continued groundwater depletion. The study calls for a comprehensive reevaluation of groundwater management policies, as existing regulations differ significantly across states, with Arizona possessing the most lenient framework.

As the impacts of climate change intensify and demand for Colorado River water grows, integrating effective groundwater management into regional water discussions appears essential for ensuring sustainable water resources in the future.

Deeper Dive: News & Info About This Topic

• The Washington Post: Drought in the American West
• Wikipedia: Colorado River
• CNN: Colorado River Basin Groundwater Loss Study
• Google Search: Colorado River water management
• The Guardian: Colorado River Basin NASA Study
• Google Scholar: Colorado River groundwater depletion
• Los Angeles Times: Colorado River Groundwater
• Encyclopedia Britannica: Groundwater
• The Hill: Colorado River Basin Groundwater Crisis
• Google News: Groundwater crisis Colorado River