Soil suitability index identifies potential areas for groundwater banking on agricultural lands

California Agriculture (UCANR) | ?

Groundwater pumping chronically exceeds natural recharge in many agricultural regions in California. A common method of recharging groundwater — when surface

Groundwater pumping chronically exceeds natural recharge in many agricultural regions in California. A common method of recharging groundwater — when surface water is available — is to deliberately flood an open area, allowing water to percolate into an aquifer. However, open land suitable for this type of recharge is scarce. Flooding agricultural land during fallow or dormant periods has the potential to increase groundwater recharge substantially, but this approach has not been well studied. Using data on soils, topography and crop type, we developed a spatially explicit index of the suitability for groundwater recharge of land in all agricultural regions in California. We identified 3.6 million acres of agricultural land statewide as having Excellent or Good potential for groundwater recharge. The index provides preliminary guidance about the locations where groundwater recharge on agricultural land is likely to be feasible. A variety of institutional, infrastructure and other issues must also be addressed before this practice can be implemented widely.

Southeast California Regional Basin Study

U.S. Bureau of Reclamation (USBR) | September 1st, 2015

The United States Department of the Interior’s WaterSMART (Sustain and Manage America’s Resources for Tomorrow) Basin Study Program is a 21st Century approach to help

The United States Department of the Interior’s WaterSMART (Sustain and Manage America’s Resources for Tomorrow) Basin Study Program is a 21st Century approach to help address water supply challenges. The Southeast California Regional Basin Study (Study) takes a collaborative approach to solve local water supply and regional conveyance and storage issues. As part of this Study, the Bureau of Reclamation’s Southern California Area Office cooperated with the Borrego Water District (BWD), Coachella Valley Water District (CVWD), Imperial Irrigation District (IID) and other interested regional stakeholders to assess water supply and demand challenges in the Southeast California region. This Study’s report is comprised of seven chapters; they are: introduction, supply, demand, alternative strategies, alternative analysis, findings, and references. Three appendices provide additional details regarding climate change modeling results, engineering design and economic analysis. The Study focuses on a regional area encompassing the Coachella, Borrego and Imperial Valleys. The Study addresses current and future supply and demand imbalances, provides an assessment of existing infrastructure resources, and develops options and alternatives to solve identified issues and help plan for an uncertain water supply future. The local stakeholders provided substantial informational resources on historical and projected supply and demand, and existing infrastructure. The water districts’ background information includes numerous groundwater, urban water and integrated regional planning studies, all of which were produced and/or updated between 2010 and 2012. Extensive supply and demand studies for the Colorado River Basin and California’s Central Valley – the two imported water supply sources for the Study area – also contributed data to this Study. Reclamation’s Colorado River Basin Water Supply and Demand Study (Colorado River Basin Study) (Reclamation, 2012) and the California Department of Water Resources biennial State Water Project (SWP) report (State of California, 2012 a and b) were both completed in 2012. Reclamation’s Colorado River Basin Study included several technical analyses related to optimal water utilization, conveyance and storage alternatives relative to climate change and future water supply uncertainty. Because the Southeast California Basin Study region is dependent on both Colorado River and SWP imports, several sections of the Study reference and/or summarize both reports extensively. Existing data was used to develop structural and non-structural options to resolve supply-demand imbalances and future uncertainty. Non-structural options included governance, and regulatory or operational changes that could facilitate stakeholder processes to better conserve water or improve the use of existing facilities to convey and store water. Non-structural options were addressed qualitatively due to the complexity of interagency negotiations that would likely be involved. The structural options involved an appraisal level design effort to evaluate pipeline alignments to convey water supplies between the Study stakeholders. Both the structural and non-structural options were assessed in their capability to resolve regional water supply and demand relative to future climate uncertainties. Climate change scenarios analyzed the potential impacts increasing temperatures and changes in precipitation may have on supply and demand across the Study area. The analysis addressed both local and imported supply sources. Climate change is expected to result in increasing temperatures across the Study area and in the Colorado River and SWP basins over time. As temperatures continue to increase, annual precipitation will become more variable. Precipitation changes may affect recharge of the Study area’s local groundwater aquifers and the Colorado River and SWP snowpacks. The climate effects on imported supply have been extensively discussed in the Colorado River Basin Study and the biennial SWP report. Increasing temperatures will increase both supply and demand uncertainty. CVWD could see an increase in SWP supply deliveries under average or greater precipitation-snowpack conditions. Dry years or extended droughts could substantially decrease SWP deliveries. However, CVWD and IID receive the majority of their supply from the Colorado River. Future climate scenarios indicate an increased potential for lower basin shortages. As senior water right holders and under the Secretary of the Interior’s Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead, IID and CVWD would not be impacted by short-term shortage issues. The Colorado River Basin Study analysis indicates these shortage vulnerabilities could be mitigated by up to 50% through a variety of management actions and operational changes. Each Study option was assessed as an adaptive strategy to climate change. The structural options to convey and store water in the Borrego Valley groundwater basin are not viable at the present time. A non-structural option may be more cost-effective for the Study region, have the potential to meet the Study objectives, and may offset climate change uncertainty that is impacting available imported water supplies. Further study effort could include fostering groundwater sustainability in the Borrego Valley and promoting opportunities for additional groundwater banking between IID and CVWD in the Coachella Valley, per an October 2003 agreement. Other water and related resource options generated from discussions during the course of this Study include increasing storage opportunities at Lake Henshaw Dam, implementing best practices for flood control basins, and brackish desalination. These options may all play a greater role in diversifying the region’s water supply in the future. However, additional study is required to assess these water resource options.

Southwestern United States drought of the 21st century presages drier conditions into the future

Nature Portfolio (Springer Nature) | September 19th, 2022

Intense drought has occurred in the United States Southwest this century, causing unprecedented stress to water resources. Here we use paleoclimate and instrumental reco

Intense drought has occurred in the United States Southwest this century, causing unprecedented stress to water resources. Here we use paleoclimate and instrumental records to establish that the recent temperature rise is incompatible with random draws from past fluctuations, including the current period of warming. Consistent with and extending previous reconstructions, we find that the ongoing drought is the most intense at the 21-year scale back to 600 CE. Evaluation using standardized regression coefficients shows that recent warming damps the effect of moisture delivery on the Standardized Precipitation-Evaporation Index by approximately one-third. The probability of full recovery of the current moisture deficit is unlikely even by mid-century and about five percent in 10-15 years. Evaluation of future climate simulations indicates increasing regional temperature stress and soil moisture depletion, and coupled with long recovery periods for moisture delivery, very low chance for regional mega-reservoirs to regain full-capacity levels assuming current demand.

Statement from ADWR Director Tom Buschatzke and CAP General Manager Ted Cooke in response to the U.S. Department of the Interior announcement of actions to protect the Colorado River system and 2023 Operating Conditions for Lake Powell and Lake Mead

Arizona Department of Water Resources (ADWR) | August 16th, 2022

Storage Capacity and Sedimentation Characteristics of the San Antonio Reservoir, California, 2018

U.S. Geological Survey (USGS) | January 15th, 2020

Storage in California’s reservoirs and snowpack in this time of drought

University of California, Davis (UC Davis) | June 30th, 2015

The San Francisco Bay and Sacramento–San Joaquin Delta (Delta) are the recipients of inflows from a watershed that spans much of California and that has ties to nearly

The San Francisco Bay and Sacramento–San Joaquin Delta (Delta) are the recipients of inflows from a watershed that spans much of California and that has ties to nearly the entire state. Historically, California has buffered its water supplies and flood risks both within—and beyond—the Delta’s catchment by devel-oping many reservoirs, large and small, high and low. Most of these reservoirs carry water from wet winter seasons—when water demands are low and flood risks are high—to dry, warm seasons (and years) when demands are high and little precipitation falls. Many reservoirs are also used to catch and delay (or spread in time) flood flows that otherwise might cause damage to communities and floodplains. This essay describes the status of surface-water and snow-pack storage conditions in California in spring 2015, providing context for better understanding where the state’s water stores stand as we enter summer 2015. 

Storage of Water on the Kings River

Scientific American | March 22nd, 1902

Kings River drains the western slope of the Sierra Nevada in Fresno County, California. from Mount Whitney on the south to Mount Goddard on the north. Fully 80 per cen

Kings River drains the western slope of the Sierra Nevada in Fresno County, California. from Mount Whitney on the south to Mount Goddard on the north. Fully 80 per cent of the drainage basin is now included within the boundaries of the Sierra Forest Reserve, a matter of prime importance to the irrigated lands below, for it means the conservation of the stream. The river debouches from its mountain drainage basin upon the plains of Fresno, Kings and Tulare counties, sometimes spoken of as the Kings River delta, which are near the geographic center of the State, and pre sent great variety of climate and soil.

Storing Water for the Environment: Operating Reservoirs to Improve California’s Freshwater Ecosystems

Public Policy Institute of California (PPIC) | August 23rd, 2022

Large reservoirs like those that rim the Central Valley are essential for managing water in California’s highly variable climate. They provide multiple benefits includi

Large reservoirs like those that rim the Central Valley are essential for managing water in California’s highly variable climate. They provide multiple benefits including water supply, hydropower, flood management, and recreation. However, construction and operation of these reservoirs have also imposed significant environmental costs, including native fishes’ loss of access to high-quality habitat above dams and degradation of freshwater ecosystems below them. Moreover, regulatory uncertainty for water users is rising as these ecosystems decline. California needs a new approach for managing environmental water in its large reservoirs, particularly as the climate warms and droughts become more intense.

Surface Storage - CalFed (Resource Management Strategy)

California Department of Water Resources (DWR) | July 29th, 2016

California remains significantly dependent upon surface water. A review of the California Water Balance Summary, 2001-2010 (California Water Plan Update 2013, Volume 1, C

California remains significantly dependent upon surface water. A review of the California Water Balance Summary, 2001-2010 (California Water Plan Update 2013, Volume 1, Chapter 3, Table 3-2), indicates that in an average year like 2010, about 65 maf (million acre-feet) (more than 80 percent) of 80 maf total dedicated and developed water supply is associated with surface water. Surface storage is an essential element of managing the state’s surface water resources. The naturally arid conditions found in much of California, coupled with seasonal variations of too much or too little water prompted water planners of the past to implement conveyance and storage projects to support land development, population, and economic growth. After construction, these dams captured seasonal runoff and stored it for beneficial uses during drier times. Today, these projects facilitate a larger set of water management objectives including reliable water supplies, water quality and ecosystem maintenance, flood management, and hydropower generation. In many areas of the state, surface water and groundwater are used conjunctively. Coordinated surface water and groundwater management can be either formal or informal. For example, a managed groundwater recharge program where surface water is infiltrated to an aquifer for later use is formal; excess applied surface water in agricultural areas during wetter years that increases the availability of groundwater in drier years is often more informal. Dams and surface water storage continue to be a critical tool for providing water management flexibility in California. The amount of surface water in California, as noted above, often make it a foundational integration element of more diverse local and regional water management portfolios. In addition to storing water for use by residents, businesses, and industries, these facilities provide vital supplies during warm and dry periods for growing crops and maintaining the state’s managed wildlife refuges.

Temporary Urgency Change Petition for February 1, 2023, through March 31, 2023

California State Water Resources Control Board (SWRCB) | February 13th, 2023