By Terry Foreman, PG, C.Hg., and Dennis Williams, Ph.D, PG., C.Hg.
January 31, 2012
The innovative Cadiz Valley Water Conservation, Recovery and Storage Project would enable water to be beneficially used in California by capturing water that is currently being lost to evaporation in the Mojave Desert. The Project is currently undergoing a public review under the California Environmental Quality Act (CEQA). As with any public process, opponents are entitled and encouraged to question CEQA documents and challenge a project’s design or assumptions. However, many of the most vocal critics of the Cadiz Project have never visited the project area or reviewed any studies and rely instead on misinformation and assumptions that are simply incorrect, untrue and wrong.
As the authors of the geologic and hydrologic studies and many of the technical reports included in the Draft Environmental Impact Report (DEIR) for the Cadiz Project, we strongly believe that the project is based on sound modern water management practices that will provide a reliable and sustainable water supply without harm to the environment. In a transparent and open public process, all supporting studies are available to the public and included as Appendices to the DEIR and are available from the following link – http://www.smwd.com/operations/cadiz-project-draft-eir.html.
Prior to inclusion of the hydrological studies in the DEIR, they were reviewed and validated by an independent peer review panel, the Project’s Groundwater Stewardship Committee (GSC). The GSC is chaired by Dr. John Sharp a professor at the University of Texas at Austin. Dr. Sharp is the leading expert in groundwater hydrology and carbonate aquifers, similar to one of the aquifers found beneath the Project area. Other members of the GSC include Dr. Charles Groat, former director of the United States Geological Survey (USGS), and international groundwater experts from the regulatory, institutional, and academic sectors. For the summary of findings of this panel, see the Groundwater Stewardship Committee report here – http://www.smwd.com/assets/downloads/GSCSum_10-20-11.pdf.
The following summarizes our responses to questions and clarifies the facts about the project:
The Water is Renewable. The Project is Sustainable.
First and foremost, extensive study has been done to validate that the water at Cadiz is a renewable resource. Using a current U.S. Geological Survey model, Infil3.0, (which was developed for desert environments and accounts for local conditions), the annual recharge to the basin is estimated at approximately 32,000 acre-feet per year. Water will continue percolating slowly into the aquifer for centuries. The estimate of 17 – 34 million acre-feet of water in the basin, and largely up-gradient of the proposed wellfield, is based on extensive test well drilling, which has been used to construct a calibrated groundwater model that was also validated with historical data. The model was calibrated over a range of recharge rates and shows that, even with no recharge, the project would only remove 2.5 million acre-feet over 50 years. This is less than approximately 10% of the available water stored in the basin.
The Water is Currently Being Lost to Evaporation.
The project area is centered in the middle of a closed basin. As the basin does not have outlets to rivers, streams, freshwater lakes, or the ocean, it is considered closed. The only discharge for the groundwater, which is slowly migrating hydraulically down-gradient (or moving downhill) towards the highly saline dry lakes, is by evaporation.
The water is generally more than 100 feet below the surface, and no plants or animals use this groundwater. Springs at the surface that are known to support wildlife also do not use groundwater; they are fed from precipitation that occurs in the highest elevations of the surrounding mountains of the watershed. The closest springs in the area are more than 10 miles up-gradient from the project area and in different geological formations than the project wells.
The springs cannot pull water against gravity to the surface from the groundwater basin hundreds of feet below ground. Precipitation that makes it into the deeper soil column in the higher elevations percolates by gravity drainage downward to the regional groundwater system, and some exits to the surface as springs in the mountains. Groundwater in the system continues downhill and eventually becomes saline beneath the dry lakes and ultimately evaporates. This fresh water is being lost and can and should be put to beneficial use.
The following link explains the hydrology of the project in detail: http://www.cadizwaterproject.com/eir/downloads/4_09_Hydrology.pdf.
Using 50,000 Acre-Feet per Year Is Optimal for Conservation.
The managed yield of the basin is considered to be that amount, which will capture and conserve annual recharge plus an optimal amount to minimize losses due to evaporation from the dry lakes. If the project only captured recharge, it would not be able to conserve water already in storage and migrating towards the dry lakes (and subsequently evaporating). Under natural conditions, approximately three-million acre-feet of fresh water will be lost in this process over the next 100 years. To stop the loss and reduce the flow of water to the dry lakes, extraction wells will pump groundwater and reverse the hydraulic gradient (or water table slope) before it reaches the highly saline brine of the dry lakes. Model results show that pumping an average of 50,000 acre-feet per year will accomplish that.
The Project has No Long-Term Impacts to the Desert Environment.
After thorough examination of the potential for the project to have an effect on the immediate project area, local environment, far reaches of the watershed, and the region as a whole, the DEIR concludes that the only unmitigable impacts are short-term emissions from heavy equipment during construction and secondary effects of growth in Southern California due to making water more reliable. (See: http://www.cadizwaterproject.com/eir/downloads/0_Exec%20Summary.pdf )
Every other potential short- or long-term impact will be mitigated. The project’s state of the art Groundwater Monitoring, Management and Mitigation Plan (GMMMP) is the most comprehensive groundwater plan proposed in the State of California. The GMMMP includes far-reaching and extensive specific monitoring measures for water, air, springs, subsidence and saline/fresh water movement to ensure that the basin is managed safely. The plan also includes extensive measures to address any concerns or impacts to other users of water in the basin. For example, potential lowering of groundwater levels in private wells or in the vicinity of the dry lakes can be addressed with measures included in the GMMMP.
Because any lowering of the groundwater level occurs very slowly, the GMMMP monitoring will detect any potential impact or conditions which are not consistent with any of the predictive surface and groundwater modeling. Changes or impacts (measured in the field-water levels, water quality and subsidence) would then be used to refine the predictive models in order to allow adjustments to be made to project operations if needed, to stop any impacts before they become significant.
The Cadiz Project Work Is In Accordance With Industry Standards.
Having physically worked in the Project site area many times over the past decade, we have physically observed geologic, hydrologic and various testing (pumping and recharge tests), for many years. The project design represents best industry practices in groundwater basin management. When compared with use of surface water and the environmental cost of moving water from the Delta or the Colorado River, the Cadiz Valley Water Conservation, Recovery and Storage Project is completely sustainable as planned. The Project will make a new reliable source of water available to Southern California for the next 50 years and could be a critical component of the water supply portfolio in the region.
Terry Foreman has over 30 years of consulting experience in water resources projects, mostly in the Southwestern United States. He has authored over 30 technical papers and presentations and is a Registered Geologist and Certified Hydrogeologist in California. He is a member of several professional organizations, where he has held many different officer positions through his active membership.
Dr. Dennis Williams has over 35 years of experience in ground water hydrology. He has been a consultant to the United Nations and is currently a part-time research professor at the University of Southern California’s Civil and Environmental Engineering Department where he has taught graduate level classes in geohydrology and groundwater modeling since 1980. He has authored over 30 publications on ground water and wells and was the principal author of the Handbook of Ground Water Development (John Wiley & Sons, 1990.)