North Coast

Toxicological assessment of potable reuse and conventional drinking waters

Nature Portfolio (Springer Nature) | October 27th, 2022

Potable reuse, the process of treating wastewater to drinkable standards, offers a reliable and sustainable solution to cities and regions facing shortages of clean water

Potable reuse, the process of treating wastewater to drinkable standards, offers a reliable and sustainable solution to cities and regions facing shortages of clean water. However, implementation is hindered by perceptions of poor water quality and potential health threats. Herein, we compare water samples from potable reuse systems with conventional drinking waters based on the analysis of Chinese hamster ovary cell cytotoxicity contributed by disinfection by-products (DBPs) and sewage-derived anthropogenic contaminants. In all cases, the cytotoxicity of potable reuse waters is lower than that of drinking waters derived from surface waters. The median contribution to total cytotoxicity was 0.2% for regulated DBPs and 16% for the unregulated DBPs of current research interest. Nonvolatile, uncharacterized DBPs and anthropogenic contaminants accounted for 83% of total cytotoxicity. Potable reuse waters treated by reverse osmosis are not more cytotoxic than groundwaters. Even in the absence of reverse osmosis, reuse waters are less cytotoxic than surface drinking waters. Our results suggest that potable reuse can provide a safe, energy-efficient and cost-effective alternative water supply.

Tracking California’s sinking coast from space: Implications for relative sea-level rise

American Association for the Advancement of Science (AAAS) | July 31st, 2020

Coastal vertical land motion affects projections of sea-level rise, and subsidence exacerbates flooding hazards. Along the ~1350-km California coastline, record

Coastal vertical land motion affects projections of sea-level rise, and subsidence exacerbates flooding hazards. Along the ~1350-km California coastline, records of high-resolution vertical land motion rates are scarce due to sparse instrumentation, and hazards to coastal communities are underestimated. Here, we considered a ~100-km-wide swath of land along California’s coast and performed a multitemporal interferometric synthetic aperture radar (InSAR) analysis of large datasets, obtaining estimates of vertical land motion rates for California’s entire coast at ~100-m dimensions—a ~1000-fold resolution improvement to the previous record. We estimate between 4.3 million and 8.7 million people in California’s coastal communities, including 460,000 to 805,000 in San Francisco, 8000 to 2,300,00 in Los Angeles, and 2,000,000 to 2,300,000 in San Diego, are exposed to subsidence. The unprecedented detail and submillimeter accuracy resolved in our vertical land motion dataset can transform the analysis of natural and anthropogenic changes in relative sea-level and associated hazards.

Trading Sustainably: Critical Considerations for Local Groundwater Markets Under the Sustainable Groundwater Management Act

University of California, Berkeley (UC Berkeley) | June 1st, 2017

The Sustainable Groundwater Management Act (SGMA), passed in 2014, is changing the way California manages its groundwater resources. SGMA calls for the creation of loc

The Sustainable Groundwater Management Act (SGMA), passed in 2014, is changing the way California manages its groundwater resources. SGMA calls for the creation of local Groundwater Sustainability Agencies (GSAs) and tasks them with developing and implementing Groundwater Sustainability Plans (GSPs) to achieve sustainable groundwater management. SGMA offers GSAs a broad palette of tools to choose from and significant flexibility to tailor their management activities to local conditions and needs. Because it allows GSAs to assign groundwater extraction allocations to pumpers and to authorize transfers of these allocations under certain circumstances, SGMA potentially opens the door for the development of local groundwater markets. In such a market, a willing seller might trade a portion of their groundwater extraction allocation to a willing buyer, allowing the buyer to pump groundwater in the seller’s stead.

Tree height explains mortality risk during an intense drought

Nature Portfolio (Springer Nature) | September 26th, 2019

Forest mortality is accelerating due to climate change and the largest trees may be at the greatest risk, threatening critical ecological, economic, and social be

Forest mortality is accelerating due to climate change and the largest trees may be at the greatest risk, threatening critical ecological, economic, and social benefits. Here, we combine high-resolution airborne LiDAR and optical data to track tree-level mortality rates for ~2 million trees in California over 8 years, showing that tree height is the strongest predictor of mortality during extreme drought. Large trees die at twice the rate of small trees and environmental gradients of temperature, water, and competition control the intensity of the height-mortality relationship. These findings suggest that future persistent drought may cause widespread mortality of the largest trees on Earth.

Tule Lake Subbasin Groundwater Sustainability Plan

Tule Lake Subbasin Groundwater Sustainability Agency | December 14th, 2021

On September 16, 2014, Governor Jerry Brown signed into law a three-bill legislative package, composed of Assembly Bill (AB) 1739 (Dickinson), Senate Bill (SB) 1168 (Pav

On September 16, 2014, Governor Jerry Brown signed into law a three-bill legislative package, composed of Assembly Bill (AB) 1739 (Dickinson), Senate Bill (SB) 1168 (Pavley), and SB 1319 (Pavley), collectively known as the Sustainable Groundwater Management Act (SGMA), which is codified in Section 10720 et seq. of the California Water Code. The purpose of this Groundwater Sustainability Plan (GSP or Plan) is to bring the Klamath River Valley – Tule Lake Subbasin (Tule Lake Subbasin or Subbasin), a medium priority basin, into sustainable groundwater management by 2042, which would meet the requirements of SGMA.

Tule Lake* Subbasin Groundwater Sustainability Plan

Tulelake Subbasin Groundwater Sustainability Agency | June 14th, 2024

*Spelled various as one and two words, Tule Lake and Tulelake, across the GSP submissions. From the GSP: "This ... covers the entire Tule Lake Subbasin, which comprises

*Spelled various as one and two words, Tule Lake and Tulelake, across the GSP submissions. From the GSP: "This ... covers the entire Tule Lake Subbasin, which comprises approximately 64,000 acres of irrigated land near the California-Oregon border. The Subbasin is part of the larger Upper Klamath Basin, which extends into Oregon, and is located within the North Coast Hydrologic Region. The Subbasin is within Modoc County and Siskiyou County, which have been respectively identified as "severely disadvantaged” and “disadvantaged” communities. The majority of land in the Subbasin is also in TID [Tulelake Irrigation District], which covers approximately 84% of the Subbasin. As the most prominent public agency within the Subbasin, TID has been the primary GSA responsible for recent planning activities." Due to length, this document has been divided. Part 1, Part 2

Twentieth-century shifts in forest structure in California: Denser forests, smaller trees, and increased dominance of oaks

National Academy of Sciences (NAS) | January 20th, 2015

Twenty-first century hydroclimate: A continually changing baseline, with more frequent extremes

National Academy of Sciences (NAS) | March 14th, 2022

Variability in hydroclimate impacts natural and human systems worldwide. In particular, both decadal variability and extreme precipitation events have substantial effect

Variability in hydroclimate impacts natural and human systems worldwide. In particular, both decadal variability and extreme precipitation events have substantial effects and are anticipated to be strongly influenced by climate change. From a practical perspective, these impacts will be felt relative to the continuously evolving background climate. Removing the underlying forced trend is therefore necessary to assess the relative impacts, but to date, the small size of most climate-model ensembles has made it difficult to do this. Here we use an archive of large ensembles run under a high-emissions scenario to determine how decadal “megadrought” and “megapluvial” events—and shorter-term precipitation extremes—will vary relative to that changing baseline. When the trend is retained, mean state changes dominate: In fact, soil moisture changes are so large in some regions that conditions that would be considered a megadrought or pluvial event today are projected to become average. Time-of-emergence calculations suggest that in some regions including Europe and western North America, this shift may have already taken place and could be imminent elsewhere: Emergence of drought/pluvial conditions occurs over 61% of the global land surface (excluding Antarctica) by 2080. Relative to the changing baseline, megadrought-/megapluvial risk either will not change or is slightly reduced. However, the increased frequency and intensity of both extreme wet and dry precipitation events will likely present adaptation challenges beyond anything currently experienced. In many regions, resilience against future hazards will require adapting to an ever-changing “normal,” characterized by unprecedented aridification/wetting punctuated by more severe extremes.

Ukiah Valley Groundwater Sustainability Plan

Ukiah Valley Groundwater Sustainability Agency (UVGSA) | January 12th, 2022

The Sustainable Groundwater Management Act (SGMA), passed by the California legislature in 2014, requires local entities to jointly assess groundwater conditions in thei

The Sustainable Groundwater Management Act (SGMA), passed by the California legislature in 2014, requires local entities to jointly assess groundwater conditions in their local areas and to develop a Groundwater Sustainability Plan (GSP) by a specified deadline to ensure that sustainable conditions are achieved within 20 years of GSP adoption. An effective and efficient groundwater management plan is critical for the local economy and the health and welfare of the people, the environment, and all other beneficial uses and users of groundwater in a local area. The Ukiah Valley Basin (Basin) is a medium-priority groundwater basin located in Mendocino County. The sole Groundwater Sustainability Agency for the Basin is the Ukiah Valley Groundwater Sustainability Agency (UVBGSA or GSA). The GSA consists of the following local agencies: the County of Mendocino (County), the City of Ukiah (City), the Upper Russian River Water Agency (URRWA), and the Russian River Flood Control and Water Conservation and Improvement District (RRFC). The GSA applied for and was awarded Proposition 1 and Proposition 68 grant funds to develop the GSP and meet the SGMA-mandated schedule for submitting a GSA-approved GSP to the California Department of Water Resources (DWR) by January 31, 2022. GSA will be funded through member agency contributions during the first 5-year implementation period until a fee structure is implemented to support and fund GSA activities. Additional funding opportunities will continue to be explored, including grants. In late-2022, DWR will open round 2 solicitations under the SGMA Grant Program, which will provide approximately $204 million to high and medium priority subbasins to implement the GSP and its projects and management actions. A variety of local interests are represented by the GSA and served on the technical advisory committee (TAC), including municipal-residential water users, agricultural water users, public water systems, local land use planning agencies, environmental users, surface water users, tribal governments, disadvantaged communities, groundwater monitoring and reporting entities, holders of overlying groundwater rights, adjacent Basins, industrial users, commercial users, remediation pumpers, natural ecosystems, and the general public. Many of these local entities have a long history with groundwater and surface water management in the Basin and are well equipped to perform SGMA-required planning functions. The GSA, TAC members, and the public have undertaken a thorough and timely review of past, current, and projected future water resources needs and groundwater conditions to meet SGMA requirements for GSP development. Throughout the development of the GSP, regular communication and engagement activities were conducted to inform and receive input from local stakeholders and the public. The GSP includes a comprehensive groundwater basin description, which was used to develop a regional integrated hydrological model that quantifies current water budgets and projects future conditions of the Basin. The GSP also includes an assessment of the impacts of predicted future groundwater levels on beneficial users, including groundwater-dependent ecosystems, shallow wells, and interconnected surface water using the best available data and science available. Importantly, these assessments are used to develop measurable sustainable management criteria that avoid significant and unreasonable impacts to these beneficial users, and that can be monitored and adjusted throughout plan implementation. The key finding of the GSP, based on a thorough analysis of the best available information, is that the Basin will be sustainable over the next twenty years if planned projects and management actions (PMAs) are implemented as needed with respect to climate change and changes in the water system. These PMAs will help maintain groundwater levels and storage volumes and protect ecosystems, interconnected surface water, and shallow wells. Potential climate change impacts are not fully understood at this stage due to data gaps and the need for additional modeling and data collection. The GSP will implement a more comprehensive data collection that improves modeling capabilities and can provide a better assessment of climate change impacts in the future. The proposed PMAs will promote adaptive management practices and long-term resiliency to varying climatic conditions, such as more frequent, longer-lasting, and more intense droughts and less frequent and wetter winters. As described in Chapter 2, the sustainable yield for the entire Basin is estimated to be at least 6,500 acre-feet, based on historical, average groundwater pumping. The sustainable yield of the Basin is defined based on avoidance of undesirable results. Because the Basin is not overdrafted and the historical pumping average may not represent the actual sustainability yield of the Basin. A groundwater monitoring network comprised of selected wells will be used to track groundwater levels and groundwater quality. Sustainable management criteria set at representative monitoring wells in the network will be implemented to gage these conditions over time and ensure that groundwater levels and quality remain within a range that avoids significant and unreasonable impacts to beneficial uses and users of groundwater. Streamflow measurements are added to the monitoring network to measure surface water depletion due to groundwater pumping in combination with groundwater level measurements and integrated hydrological modeling simulations. Monitoring and data collection efforts will continue through the first five years of GSP implementation to further identify and prioritize project and management actions. Once approved by the GSA, the activities identified throughout the GSP development process will be implemented, including: • Ongoing monitoring and annual reporting on conditions in the Basin; • Ongoing public engagement and outreach; • Coordination within the watershed and with neighboring basins and water management entities; • Development and implementation of a shallow well protection and monitoring program; • Coordination with land use agencies and water supply agencies to promote consistency with the GSP; • Coordination with regional agencies in the development of updated climate change projections; • Implementing PMAs as deemed needed by the GSA to maintain and promote sustainability of the Basin; and, • Preparation of five-year updates to the GSP starting in 2027. Due to file size, the GSP is divided into separate files. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6  

Uncertainty in El Niño-like warming and California precipitation changes linked by the Interdecadal Pacific Oscillation

Nature Portfolio (Springer Nature) | November 10th, 2021

Marked uncertainty in California (CA) precipitation projections challenges their use in adaptation planning in the region already experiencing severe water stress. Under

Marked uncertainty in California (CA) precipitation projections challenges their use in adaptation planning in the region already experiencing severe water stress. Under global warming, a westerly jet extension in the North Pacific analogous to the El Niño-like teleconnection has been suggested as a key mechanism for CA winter precipitation changes. However, this teleconnection has not been reconciled with the well-known El Niño-like warming response or the controversial role of internal variability in the precipitation uncertainty. Here we find that internal variability contributes > 70% and > 50% of uncertainty in the CA precipitation changes and the El Niño-like warming, respectively, based on analysis of 318 climate simulations from several multi-model and large ensembles. The Interdecadal Pacific Oscillation plays a key role in each contribution and in connecting the two via the westerly jet extension. This unifying understanding of the role of internal variability in CA precipitation provides critical guidance for reducing and communicating uncertainty to inform adaptation planning.