Cuyama Valley groundwater depleted twice as fast than it naturally recharges, California


In California's Cuyama Valley, Santa Barbara County, groundwater is the sole source for agricultural, domestic and municipal water use. However, a new water availability report from USGS warns that groundwater there is being depleted twice as fast than it naturally recharges. Aside from the obvious, this alarming rate of depletion is degrading the overall water quality, and potentially leading to the onset of land subsidence.

According to the study, an estimated 2.1 million acre-feet of groundwater have been removed from storage in the Cuyama Valley aquifer system since 1949. One acre-foot is approximately 325 000 gallons or enough to cover one acre of land with one foot of water. The study found that groundwater pumping for irrigated agriculture accounts for almost all groundwater withdrawals in the region.

The total average annual pumpage of groundwater in the Cuyama Valley aquifers system from water years 1950 – 2010 was about twice the average estimated long-term annual recharge rate.

Cuyama Valley groundwater basin and sub-basins.

Change in groundwater storage with rapidly declining water levels in a sole-source aquifer were important factors in undertaking and completing this study. To better understand the system, the Cuyama Valley has been split into three groups of subregions: (1) the Main Zone, (2) the Sierra Madre Foothills, nd (3) the Ventucopa Uplands. Although partially connected hydraulically, the groupdwater system in these subregions generally responds independently to different supply sources and demands.

During the course of the five-year study, conducted in cooperation with the Santa Barbara County Water Agency, scientists discovered that the geologic structure of the valley is composed of three groups of subregions in the valley – The Main zone, the Sierra Madre Foothills, and the Ventucopa Uplands; each with distinct geologic, hydrologic, and water-quality characteristics.

This is important because groundwater withdrawals as well as natural and human-caused recharge affect each sub-basin differently. In the Main zone sub-basin which comprises about a third of the modeled groundwater basin, groundwater pumping for irrigation exceeds the natural replenishment rate, thus depleting groundwater storage, degrading water quality, and potentially leading to the onset of land subsidence. 

Since 2000, groundwater pumping has led to land subsidence of up to 0.2 feet. Model analyses of historical conditions indicate that 1.6 feet of subsidence has occurred near the town of New Cuyama since the onset of development in the 1940s, coincident with the groundwater declines in the Main zone. An additional foot of permanent subsidence is projected in the Main zone through 2071 if current demand and replenishment rates continue.

In addition to extensive data collection, the USGS developed hydrologic models of Cuyama Valley to analyze water availability, account for changing water supply and demand, and simulate surface water and groundwater flow across the entire valley. These models can be used to address issues related to water resource sustainability, including the effects of changing land-use patterns and a changing climate on water resources. The models can also incorporate how changes in water supply and demand will affect water quality and land subsidence.  

The new water availability report and related summary fact sheet are available on-line.

A complete list of USGS publications related to the Cuyama Valley study is provided below:

Source: USGS

Featured image: Cuyama Valley by Jesse Palmer (CC – Flickr)

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  1. 60-yr water scam. Cities rebuilt on top of secretly-replaced water infrastructure. According to ringleader, Wilbert Swieso (with 60 yrs into this), began as a Bonadelle / City of Fresno op. Water being redirected for upcoming development of gambling communities casinos, race tracks, golf course. New dams / waterways. Farmers replaced with solar farms. High-speed rail. Records altered to cover up what is taking place – City of Fresno behind perjury and threats for exposing. They did not foresee a REAL water shortage on top of the one they created. Tragic.

  2. And that same rate of aquifer depletion is occurring across most of the Southwestern US and Mexico too, with some areas mining more than double the recharge rate.

    Other aquifers, such as the mostly agricultural Ogallala Aquifer, can't be readily recharged and are today rapidly being depleted, while still other aquifers are being polluted by the fracking industry and wastewater injection.

    Meanwhile, across most of the Southwestern US and Mexico, annual runoff has been declining while snow and alpine vegetation levels move northward and higher in elevation.

    Both the Colorado and the upper Rio Grande rivers have already seen a 30-35% average annual runoff reduction over the last 40 years as have other smaller basins.

    On the current rate of reduction in annual runoff, aquifer mining, population growth, and the rate of increasing temperature, rising surface water evaporation rates, and decreasing soil moisture 200 million people or more are staring a water-scarcity catastrophe in the face.

    Such a water-scarcity catastrophe will eventually cost a fair percentage their homes and businesses after it becomes impossible to continue to supply them with enough food and water to survive, my academic field exactly.

    So what do you think, take honest steps to reduce fossil fuel emissions and reduce our population growth rate or even steps to reduce population,


    Do we charge ahead and build several dozen major water pipelines from northern Canada and keep drilling for, mining, and burning ever more fossil fuels hoping to drive ever more economic and population growth until absolute disaster strikes?

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