Geology and Ground Water Features of the Butte Valley Region Siskiyou County California

U.S. Geological Survey (USGS) | January 14th, 1960

The Butte Valley region includes an area of about 600 square miles, between long 121°37' and 122°10' W. and lat 41°38' and 42° N., in northern Siskiyou County, Cali

The Butte Valley region includes an area of about 600 square miles, between long 121°37' and 122°10' W. and lat 41°38' and 42° N., in northern Siskiyou County, Calif. U.S. Highway 97, connecting Weed with Klamath Falls, traverses the region in a northeasterly direction, and the Southern Pacific railroad serves several small farming communities in Butte Valley. The region is near the west edge of the Modoc plateau. It includes along its western border a part of the Cascade Range, Butte and Red Rock Valleys, the Oklahoma district, and a prominent northwestward-trending fault block (the Mahogany Mountain ridge) which separates Butte Valley fro-n the Oklahoma district and the Lower Klamath Lake marshland. Geologic units have been divided into two groups: Volcanic rocks which range in age from Eocene to Recent; and sedimentary rocks which range in age from Pliocene to Recent. From oldest to youngest the volcanic rocks include: (a) Predominantly andesitic lavas and pyroclastic rocks comprising the volcanic rocks of the "Western Cascades"; (b) older volcanic rocks of the "High Cascades"; (c) basaltic flows and pyroclastic rocks east of the Cascade Rang; and (d) younger volcanic rocks of the "High Cascades." Volcanic rocks of the "Western Cascades" are the oldest rocks in the region. They range in age from late Eocene to late Miocene. These rocks are chiefly pyroxene andesite, and andesitic tuff-breccia, but include lesser amounts of basalt, rhyolite, and associated pyroclastic rocks. In most places they are badly decomposed and less permeable than the younger volcanic rocks. They are best exposed in the Klamath River canyon, where the prevailing dips are to the east and northeast. The angle of dip diminishes in these directions from about 15° near the base of the series to nearly zero where the rocks disappear beneath a younger series of volcanic rocks designated on plate 1 as the older volcanic rocks of the "High Cascades." The volcanic rocks of the "Western Cascades" are at least 12,000 feet thick. The older volcanic rocks of the "High Cascades," which UE conformably overlie the volcanic rocks of the "Western Cascades," are Pliocene and Pleistocene (?) in age. They consist chiefly of basalt and basaltic andesite that spread out in successive sheets from a chain of northward-trendinr shield volcanoes built along the crest of the Cascade Range. Here the topography is almost wholly constructional, and even the oldest cones retain much of their original shape. East of the Cascade Range several large dome-shaped lava cones and most of the northwestward-trending fault block called Mahogany. Mountain ridge are composed of volcanic rocks of similar lithology. In most places the older volcanic rocks of the "High Cascades" are highly fractured and moderately permeable; they serve as a large intake area and groundwater reservoir. East of the Cascade Range, basalt of Pleistocene and Recent age issued from vents and fissures and spread out over alluvial deposits and lava sediments in the southern parts of Butte and Red Rock Valleys and the Lover Klamath Lake marshland. One of these flows the Butte Valley basalt forms the most productive water-bearing formation in the region. In the southwestern part of Butte Valley, where it is overlain by about 20 to 60 feet; of alluvial materials and lake deposits, this basaltic flow is an excellent aquifer. Yields of more than 100 gpm (gallons per minute) for each foot of drawdown are common and yields of 1,000 gpm for each foot of drawdown have been recorded. Late Pleistocene and Recent lava flows and cinder cones in the Cascade Range and extensive basaltic extrusions near Sharp Mountain are important chiefly as recharge (intake) areas for ground water. Sedimentary deposits range in age from Pliocene to Recent. The oldest of these deposits is a massive fresh-water diatomite which underlies a large part of the Oklahoma district. The diatomite is impermeable, but wells penetrating interbedded sand or cindery lapilli lenses in the diatomite may yield moderate quantities of water. Glacial moraines and fluvioglacial outwash deposits of late Pleistocene age occur near the mouth of Butte Creek canyon. These deposits are unstratified or poorly sorted and commonly are only slightly permeable. Semi-consolidated lake deposits, ranging in age from Pleistocene to Recent, underlie most of the Butte Valley plain. West of U.S. Highway 97 these deposits are composed principally of impermeable layers of clay, diatomaceous clay, and volcanic ash. However, east of U.S. Highway 97, and especially near the eastern border of the valley, the lake deposits contain a larger percentage of sand, and permeabilities range from about 50 to 230 gpd per square foot as determined from tests made in 3 pumped wells. Alluvial-fan deposits on the west side of Butte Valley range from Pleistocene to Recent in age. They are composed of poorly sorted rock debris derived from the Cascade Range and are only slightly permeable. Areas mapped as alluvium include thin beds of gravel, sand, dry, and peat covering older lake deposits in Butte Valley and the area around Lower Klamath Lake. They include also small playa deposits, poorly sorted alluvium collected in broad, shallow basins and depressions, and alluvluir in present intermittent stream channels. In most places alluvium forms a thin cover resting on lava flows or lake deposits. In general the alluviuir is slightly permeable and of little hydrologic importance except in the southwestern part of Butte Valley, where it consists of sand and gravel, ranging in thickness from 20 to 60 feet and rests on the Butte Valley basalt. In this area the alluvium probably yields moderate quantities of water to wells. Elsewhere the alluvium is largely above the saturated zone and is important chiefly because of its ability to absorb precipitation and surface runoff which percolate through it into underlying rocks. Linear wedge-shaped talus strips, formed at the foot of precipitous fault scarps, are partly concealed beneath and probably interfinger with alluvium and lake deposits. The blocky talus debris is very permeable and, where saturated, yields water readily to wells. East of the Cascade Range, block faulting is the dominant structural feature. The faults are normal and displacement is almost wholly vertical. Vertical displacements range from a few feet along minor faults to perhaps several thousand feet along major faults; there are no appreciable horizontal displacements. Butte Valley is a complexly downfaulted basin nearly surrounded by well-preserved fault scarps of late Pleistocene and Recent age. Groundwater moves eastward and northeastward across the valley into the buried talus and volcanic rocks that compose the Mahogany Mountain ridge, and may flow through that ridge to supply recharge to the area to the east. Th« direction of water movement in Red Rock Valley and in the Oklahoma district was not determined. Records of water-level fluctuations in observation wells show that water levels recover each winter, and during the period 1951-54 there was little overall change in the height of yearly recovery. Ground-water recharge in the southern part of the region occurs mainly by seepage loss from perennial spring-fed streams and unlined canals along the western margin of Butte Valley, by seepage loss from small spring-fed streams that discharge onto alluvial fans, and along the north, west, and south sides of the valley by lateral movement from the volcanic rocks. In irrigated tracts throughout the area some recharge probably occurs by deep percolation of irrigation water. Ground water is discharged by natural means and by pumping. In Butte Valley about 21,000 acre-feet of ground water was used for irrigation in 1953. In Red Rock Valley pumping of ground water for irrigation purposes was negligible. In the Oklahoma district ground water for irrigation and domestic requirements is supplied by springs and flowing and pumped wells. The quality of most of the ground water in the region is satisfactory for most uses, but in the east-central part of Butte Valley some wells yield water containing high percentages of sodium, probably derived from buried playa deposits. The chemical quality of the surface water is such that it can be used for most purposes. However, analyses of water from Meiss Lake show high concentrations of dissolved solids, ranging from 473 to 1,380 ppm, and high percentages of sodium, ranging from 75 to 91. Here the salts have been concentrated by evaporation of the lake water.

Geology and Ground-Water Features of Shasta Valley, Siskiyou County California

U.S. Geological Survey (USGS) | January 15th, 1959

Shasta Valley is in the central part of Siskiyou County, Calif., and about 12 miles south of the Oregon border. It lies between the Klamath Mountains on the west and th

Shasta Valley is in the central part of Siskiyou County, Calif., and about 12 miles south of the Oregon border. It lies between the Klamath Mountains on the west and the Cascade Range 011 the east. The valley has an area of about 250 square miles; the north-south length is about 30 miles and the maximum width is about 15 miles. The average precipitation from July 1 to June 30 at Yreka and Montague is about 17 and 12 inches, respectively, and the average annual temperature at Yreka is 51.5°F. The area has a population of about 12,000, most of whom are employed in farming, cattle raising, and lumbering. The farm income is derived chiefly from livestock, principally beef cattle, hogs, and sheep. Alfalfa, wheat, barley, oats, and rye are the main crops grown in the valley. The Klamath Mountains are underlain by metamorphic and sedimentary rocks of Paleozoic age and by intrusive rocks of Mesozoic age that form the basement complex. Near Yreka the Chico formation of Late Cretaceous age, which is composed of shale, sandstone, and some conglomerate, overlies the older rocks with profound unconformity. The Chico formation in turn is overlain disconformably by the Umpqua formation of Eocene age, which consists mainly of black shale. These rocks are covered by a thin veneer of older alluvium which floors much of the northern part of the valley. Volcanic rocks make up much of the valley floor from Montague southward to Edgewood. The southeastern, flatter part of the valley is occupied by the Plutos Cave basalt, which is a relatively large single flow erupted from the northeast flank of Mount Shasta within the last few thousand years. The western half of the valley floor is occupied largely by the older volcanic rocks of the western Cascades, which range in age from Eocene to Miocene and which have been eroded into hillocks that range in height from a few feet to as much as 300 feet. Between these hillocks lie many small ponds and marshes and the alluvial flats formed by slow, winding streams. The valley is drained principally by the Shasta River and Parks Creek, which rise in the Klamath Mountains, and the Little Shasta River, which rises in the high Cascades. The volcanic rocks of the high Cascades were built by eruptions that commenced at the close of the Miocene epoch and continued intermittently to Recent time. Mount Shasta was built mainly during the Pleistocene epoch. Morainal and fluvioglacial deposits, which are concentrated at the south end of the valley, were formed mainly during Pleistocene time by glaciers that descended the northwest flanks of Mount Shasta. Glaciers still remain on Mount Shasta and have supplied fluvioglacial debris to the valley during Recent time. The Plutos Cave basalt constitutes the principal aquifer in the valley, yielding abundant water for irrigation, stock, and domestic wells in the vicinity of Big Springs. Yields of irrigation wells in the basalt average about 1,300 gpm (gallons per minute). The andesitic lavas of the western Cascades supply sufficient water for domestic and stock uses. Yields of wells tapping the andesites vary greatly because of rapid changes in lateral and vertical permeability. Abundant water for irrigation is yielded from fractures in the volcanic rocks of the western Cascades in the Gazelle-Grenada area. The basement complex and the Chico and Umpqua formations are tapped by relatively few wells in the area, although locally these wells seem to yield sufficient water for domestic and stock uses. The basement complex yields water from joints, faults, shear zones, and openings along foliation planes. The morainal and fluvioglacial deposits generally yield sufficient water for domestic and stock uses. Several irrigation wells tapping glacial materials east of Edgewood yield 600 to 1,500 gpm. The younger and older alluviums of Recent and Pleistocene age yield water sufficient for domestic and stock uses. Along the west side of the valley the younger alluvium yields sufficient water for irrigation and supplies Yreka with abundant water for municipal uses. Ground water moves generally northward in the southern part of Shasta Valley and troughward from the east and west, converging toward the Shasta River along the valley axis. At the north end of the valley an eastward-trending divide separates the ground water that moves north to Willow Creek from ground water that moves south to the Shasta River. Recharge to ground water is effected by deep infiltration of precipitation that falls on the tributary drainage area, principally the western slopes of Mount Shasta, and by seepage from streams. The mean annual precipitation on the valley floor of 12-15 inches probably is not sufficient to contribute much recharge to ground water, but during years of above-average precipitation some deep penetration probably occurs. Recharge from irrigation water in 1953 was about 15,000 acre-feet from a total surface-water diversion of 58,000 acre-feet, and recharge from ground water pumped for irrigation was about 2,000 acre-feet. Ground-water discharge in Shasta Valley occurs principally by seepage into streams, which is estimated crudely to have been 70,000 acre-feet in 1953. Big Springs has an annual discharge of about 30,000 acre-feet. Evapotranspiration from subirrigated crops is estimated to have been 28,000 acre-feet in 1953. Pumpage for all uses in 1953 was approximately 6,000 acre-feet, and net draft was about 4,000 acre-feet. Ground-water discharge in 1953 by all these principal means was about 130,000 acre-feet. In addition, there was minor discharge from flowing wells, unestimated discharge from small springs on the valley floor, and evapotranspiration losses from relatively small areas of phreatophytes. Because of the relatively small pumpage in the valley, water levels in wells show declines of only 5-10 feet during the summer and autumn. So far as is known, the levels each winter and spring recover nearly completely, and as of 1953 there had been no indication of a long-term decline of water levels in the valley. Surface water and ground water are generally low in dissolved mineral content and with few exceptions meet minimum standards for irrigation and domestic use. A close correlation exists between the composition of the various rock types in the area and the mineralization of surface and ground waters in areas adjacent to each rock type.

Geology of the Fresh Ground‐water Basin of the Central Valley, California, with Texture Maps and Sections

U.S. Geological Survey (USGS) | December 1st, 1986

The Central Valley of California, which is about 400 miles long and averages about 50 miles wide, comprises about 20,000 square miles. Geologically, the valley is

The Central Valley of California, which is about 400 miles long and averages about 50 miles wide, comprises about 20,000 square miles. Geologically, the valley is a large asymmetric trough that is bounded by granitic, metamorphic, and marine sedimentary rocks of pre-Tertiary age. The trough has been filled with as much as 6 vertical miles of sediment in the San Joaquin Valley and as much as 10 vertical miles of sediment in the Sacramento Valley; these sedi- ments range in age from Jurassic to Holocene. Some volcanic rocks and deposits crop out in the valley, but of those only the Tuscan Formation in the northeastern part of the Sacramento Valley is of major importance to the fresh ground-water basin. Post-Eocene continental rocks and deposits contain most of the fresh water in the Central Valley; they crop out virtually over the whole valley and in most places overlie or contain saline water at depth. Continental rocks and deposits of Tertiary age include the Mehrten Formation. The Mehrten is of great importance to the fresh ground-water basin of the Central Valley and yields large quantities of water to wells.

Geology, Ground-Water Hydrology, Geochemistry, and Ground-Water Simulation of the Beaumont and Banning Storage Units, San Gorgonio Pass Area, Riverside County, California

U.S. Geological Survey (USGS) | December 14th, 2006

Ground-water has been the only source of potable water supply for residential, industrial, and agricultural users in the Beaumont and Banning storage units of the San Gor

Ground-water has been the only source of potable water supply for residential, industrial, and agricultural users in the Beaumont and Banning storage units of the San Gorgonio Pass area, Riverside County, California. Ground-water levels in the Beaumont area have declined as much as 100 feet between the early 1920s and early 2000s, and numerous natural springs have stopped flowing. In 1961, the San Gorgonio Pass Water Agency (SGPWA) entered into a contract with the California State Department of Water Resources to receive 17,300 acre-feet per year of water to be delivered by the California State Water Project (SWP) to supplement natural recharge. Currently (2005), a pipeline is delivering SWP water into the area, and the SGPWA is artificially recharging the ground-water system using recharge ponds located along Little San Gorgonio Creek in Cherry Valley with the SWP water. In addition to artificial recharge, SGPWA is considering the direct delivery of SWP water for the irrigation of local golf courses and for agricultural supply in lieu of ground-water pumpage. To better understand the potential hydrologic effects of different water-management alternatives on ground-water levels and movement in the Beaumont and Banning storage units, existing geohydrologic and geochemical data were compiled, new data from a basin-wide ground-water level and water-quality monitoring network were collected, monitoring wells were installed near the Little San Gorgonio Creek recharge ponds, geohydrologic and geochemical analyses were completed, and a ground-water flow simulation model was developed. The San Gorgonio Pass area was divided into several storage units on the basis of mapped or inferred faults. This study addresses primarily the Beaumont and Banning storage units. The geologic units in the study area were generalized into crystalline basement rocks and sedimentary deposits. The younger sedimentary deposits and the surficial deposits are the main water-bearing deposits in the San Gorgonio Pass area. The water-bearing deposits were divided into three aquifers: (1) the perched aquifer, (2) the upper aquifer, and (3) the lower aquifer based on lithologic and downhole geophysical logs. Natural recharge in the San Gorgonio Pass area was estimated using INFILv3, a deterministic distributed- parameter precipitation-runoff model. The INFILv3 model simulated that the potential recharge of precipitation and runoff in the Beaumont and Banning storage units was about 3,710 acre-feet per year and that the potential recharge in 28 sub-drainage basins upstream of the storage units was about 6,180 acre-feet per year. The water supply for the Beaumont and Banning storage units is supplied by pumping ground water from wells in the Canyon (Edgar and Banning Canyons), Banning Bench, Beaumont, and Banning storage units. Total annual pumpage from the Beaumont and Banning storage units ranged from about 1,630 acre-feet in 1936 to about 20,000 acre-feet in 2003. Ground-water levels declined by as much as 100 feet in the Beaumont storage unit from 1926–2003 in response to ground-water pumping of about 450,160 acre-feet during this period. Since ground-water development began in the San Gorgonio Pass area, there have been several sources of artificial recharge to the basin including return flow from applied water on crops, golf courses, and landscape; septic-tank seepage; and infiltration of storm runoff diversions and imported water into recharge ponds. Return flow from applied water and septic-tank seepage was estimated to reach a maximum of about 8,100 acre-feet per year in 2003. Owing to the great depth of water in much of study area (in excess of 150 feet), the return flow and septic-tank seepage takes years to decades to reach the water table. Stable-isotope data indicate that the source of ground-water recharge was precipitation from storms passing through the San Gorgonio Pass as opposed to runoff from the higher altitudes of the San Bernardino Mountains. In addition, these data indicate that little if any of the ground water in the fractured crystalline rocks flows across the Banning Fault into the Beaumont storage unit. Tritium concentrations indicate that little to no recharge has reached the water table since 1952 in most areas of the Beaumont and Banning storage units. In general, the uncorrected carbon-14 ages of ground water sampled from wells in the Beaumont, Banning, and surrounding storage units ranged from about 400 to 17,500 years before present. The older water was sampled in southeastern part of Beaumont storage unit and in the Banning storage unit, and ranged from 1,900 to 17,500 years before present. To better understand the dynamics of ground-water flow and the potential effects of water-level changes resulting from artificial recharge in the San Gorgonio Pass area, a regional-scale, numerical ground-water flow model was developed using MODFLOW-96. This model will be used by water managers to help manage the ground-water resources in the San Gorgonio Pass area. Results of the steady-state simulation indicate that the total inflow rate, or recharge, was about 6,590 acre-feet per year with about 3,710 acre-feet per year from areal recharge, about 2,670 acre-feet per year from mountain-front recharge, and about 210 acre-feet per year from the surrounding older sedimentary deposits. The simulated water budget for 1926–2003 indicates that of the total simulated volume of water pumped from the aquifer (450,160 acre-feet), about 50 percent was derived from depletion of ground-water storage (222,660 acre-feet), about 21 percent was derived from the reduction of underflow to the Cabazon and San Timoteo storage units (about 96,280 acre-feet), about 19 percent was derived from a reduction of ground-water outflow to the stream channels draining the San Timoteo storage unit (about 86,030 acre-feet), about 8 percent was derived from irrigation return flows and septic-tank seepage (about 36,780 acre-feet), and about 2 percent was derived from an increase in ground-water underflow from the surrounding older sedimentary deposits (about 8,410 acre-feet). The calibrated ground-water flow model was used to simulate the effects of four water-management scenarios being considered by SGPWA for the period 2004–13. In general, the results of the water-management scenarios indicate that artificial recharge in the Little San Gorgonio Creek recharge ponds primarily benefits the area north of the Cherry Valley Fault. For the scenario that used SWP water in lieu of ground water for golf course irrigation and for agricultural use, hydraulic heads increased by about 50 feet. None of the water-management scenarios significantly benefited the Banning storage unit.

Geology, Water-Quality, Hydrology, and Geomechanics of the Cuyama Valley Groundwater Basin, California, 2008–12

U.S. Geological Survey (USGS) | July 11th, 2013

To assess the water resources of the Cuyama Valley groundwater basin in Santa Barbara County, California, a series of cooperative studies were undertaken by the U.S. Geol

To assess the water resources of the Cuyama Valley groundwater basin in Santa Barbara County, California, a series of cooperative studies were undertaken by the U.S. Geological Survey and the Santa Barbara County Water Agency. Between 2008 and 2012, geologic, water-quality, hydrologic and geomechanical data were collected from selected sites throughout the Cuyama Valley groundwater basin.

Getting Involved in Groundwater: A Guide to California's Groundwater Sustainability Plans

Union of Concerned Scientists | September 1st, 2017

Using this guide and online toolkit, a diverse range of people can equip themselves to effectively participate in shaping the vision and plan for their community around m

Using this guide and online toolkit, a diverse range of people can equip themselves to effectively participate in shaping the vision and plan for their community around maintaining groundwater supplies. While technical expertise is a critical element of developing a successful groundwater sustainability plan, the community, with clarity around its values and goals, must lead the way. Community members and other interested people are needed to actively participate in groundwater sustainability planning. The law specifically calls for the engagement of diverse voices, and your involvement will help produce the strongest plan. This guide explains what’s at stake, shows you several entry points into the process, and suggests important questions to ask your Groundwater Sustainability Agency board members, technical experts, and others as you work toward a groundwater sustainability plan rooted in your community’s values. For Groundwater Sustainability Agency board members and advisory committee members, this document offers guidance for designing groundwater sustainability plans with community participation in mind. Since individual groundwater basins have different needs, this guide does not aim to be a comprehensive manual. Rather, it provides some critical questions to ask other advisory committee members and board members, stakeholders, and the technical experts with whom you’ll likely be collaborating. This guide can also help scientists, technical experts and consultants understand the interplay between technical information, community values, and perceived problems and/or benefits that will guide the definition of sustainability in a groundwater sustainability plan.

Global and Regional Sea Level Rise Scenarios for the United States

National Oceanic and Atmospheric Administration (NOAA) | January 15th, 2017

The Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program (USGCRP) and the Natio

The Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program (USGCRP) and the National Ocean Council (NOC), began its work in August 2015. The Task Force has focused its efforts on three primary tasks: 1) updating scenarios of global mean sea level (GMSL) rise, 2) integrating the global scenarios with regional factors contributing to sea level change for the entire U.S. coastline, and 3) incorporating these regionally appropriate scenarios within coastal risk management tools and capabilities deployed by individual agencies in support of the needs of specific stakeholder groups and user communities. This technical report focuses on the first two of these tasks and reports on the production of gridded relative sea level (RSL, which includes both ocean-level change and vertical land motion) projections for the United States associated with an updated set of GMSL scenarios. In addition to supporting the longer-term Task Force effort, this new product will be an important input into the USGCRP Sustained Assessment process and upcoming Fourth National Climate Assessment (NCA4) due in 2018. This report also serves as a key technical input into the in-progress USGCRP Climate Science Special Report (CSSR). 

Global Application of the Atmospheric River Scale

American Geophysical Union (AGU) | January 18th, 2023

Global water availability boosted by vegetation-driven changes in atmospheric moisture transport

Nature Portfolio (Springer Nature) | October 31st, 2022

Surface-water availability, defined as precipitation minus evapotranspiration, can be affected by changes in vegetation. These impacts can be local, due to the modificati

Surface-water availability, defined as precipitation minus evapotranspiration, can be affected by changes in vegetation. These impacts can be local, due to the modification of evapotranspiration and precipitation, or non-local, due to changes in atmospheric moisture transport. However, the teleconnections of vegetation changes on water availability in downwind regions remain poorly constrained by observations. By linking measurements of local precipitation to a new hydrologically weighted leaf area index that accounts for both local and upwind vegetation contributions, we demonstrate that vegetation changes have increased global water availability at a rate of 0.26 mm yr−2 for the 2001–2018 period. Critically, this increase has attenuated about 15% of the recently observed decline in global water availability. The water availability increase is due to a greater rise in precipitation relative to evapotranspiration for over 53% of the global land surface. We also quantify the potential hydrological impacts of regional vegetation increases at any given location across global land areas. We find that enhanced vegetation is beneficial to both local and downwind water availability for ~45% of the land surface, whereas it is adverse elsewhere, primarily in water-limited or high-elevation regions. Our results highlight the potential strong effects of deliberate vegetation changes, such as afforestation programmes, on water resources beyond local and regional scales.

Goal-based water trading expands and diversifies supplies for enhanced resilience

Nature Portfolio (Springer Nature) | February 11th, 2019

In response to rising water scarcity concerns around the world, water utilities are expanding and diversifying their water supply portfolios, including attempting to valu

In response to rising water scarcity concerns around the world, water utilities are expanding and diversifying their water supply portfolios, including attempting to value and reuse every drop throughout the water cycle. This transition is creating new hybrid infrastructure systems that combine centralized and decentralized sources at various scales. To help strategize and manage these emerging hybrid systems, we introduce a flexible goal-based water-trading framework using a combination of regulatory and market incentives. We apply this framework in a simulation of the San Francisco Bay Area, and test the effects of policy parameters, local preferences and collaboration between utilities. Results show that the option of engaging in an open trading scheme can lead to a more strategic and holistic path to higher regional resiliency through increased diversity in water portfolios, at lower costs than if utilities were tasked with pursuing goals independently. Highest benefits are observed when utilities cooperate in the exchange of information, which highlights the importance of transparency and trust operating in conjunction with regulatory and market forces.