We’re Depleting Our Groundwater Faster Than Ever and What This Means
Scott Stuk of the Arizona Department of Water Resources drops a probe down an unused well to measure the groundwater level south of Maricopa. The water was 280 feet down. Image: Mark Henle/The Arizona Republic
Water that’s stored in aquifers makes up the majority of accessible freshwater on Earth–it’s literally the lifeline for humans as 70% of groundwater use worldwide is used for agriculture. But, as Science News explained, “surface waters — rivers and streams — rely on groundwater, too. When people pump too much too quickly, natural waterways begin to empty, compromising freshwater ecosystems.” We’re seeing groundwater depletion play out in states like California and Arizona where communities, as well as farmers, are having to face the consequences of diminished water access.
Managing Groundwater in California: The state of California not only has the nation’s highest population but also produces the most food. Sustaining such a high population as well as a thriving agricultural industry requires a lot of water and the state’s groundwater aquifers are being depleted far faster than they can be replenished. That’s why in 2014 state lawmakers and then-Governor Brown passed the Sustainable Groundwater Management Act, or SGMA, which aims to overhaul the way growers, cities and other water users manage the resource. According to Fresno’s ABC 30:
- SGMA will take effect on January 2020, which will set new limits on how much groundwater can be pumped out of wells.
- California will be divided into Groundwater Sustainability Agencies. Each will be expected to generate reports to the state with water table information and what steps were taken to conserve water, such as the use of groundwater recharge facilities.
Water Woes in Arizona: Arizona is facing the reality of running out of water from its primary source as Lake Mead hits “dead pool” or the point at which the level in the giant man-made lake falls so low that water can no longer be pumped out. Additionally, in sprawling Phoenix, developers have built entire neighborhoods in the desert that are completely dependent on groundwater. As the Arizona Republic recently wrote,
- In theory, the Central Arizona Groundwater Replenishment District (CAGRD) was supposed to replenish sources of surface water (like the Central Arizona Project Canal) to help offset groundwater pumping but these alternative sources are becoming harder to find. The CAGRD can no longer get replenishment water from the Colorado River as conservation efforts have limited supply.
- As a result of more subdivisions being built and a dwindling water supply, homeowners have begun paying higher assessments to cover replenishment costs.
Imminent Threat: A study in the journal Nature has revealed the urgency of groundwater depletion across the globe. As Science News summed up:
- A healthy aquifer buttresses ecosystems against seasonal fluctuations in water availability, providing stability for resident plants and animals. But if too much groundwater is pumped, surface waters begin to seep into the aquifer, draining the life from many river and stream habitats.
- This ecological tipping point, what scientists call the environmental flow limit, has already been reached in 15 to 21% of watersheds tapped by humans.
- If pumping continues at current rates, the authors estimate that by 2050, anywhere from 42-79% of pumped watersheds will have crossed this threshold.
Why This Matters: Overuse of groundwater and surface water is fundamentally an environmental justice issue. Big interests like agriculture as well as cities with political capital have historically procured water resources from rivers for themselves while leaving lower-income communities with diminished access. An example of this is the fact that a series of damns and corrupt historical agreements prevent Colorado River water from flowing into Mexico. This is destroyed entire ecosystems as well as the way of life for indigenous people. Groundwater aquifers are not limitless and need to be carefully managed the world over to meet the needs of all people who depend on them.
Go Deeper: You can read the story of “The lost river” from the Guardian as they launch a year-long series, Our Unequal Earth, to investigate environmental inequalities and discrimination in the US and beyond.