Ocean, Harbor and Bay Water Quality Report 2019-2020

Orange County Health Care Agency (OCHCA) | April 30th, 2021

The 2019–2020 Ocean, Harbor and Bay Water Quality Report provides updated data on sewage spills and their impacts resulting in ocean water closures and provid

The 2019–2020 Ocean, Harbor and Bay Water Quality Report provides updated data on sewage spills and their impacts resulting in ocean water closures and provides an analysis of bacteriological water quality data collected at Orange County’s (OC) ocean, harbor and bay waters.

Ocean, Harbor and Bay Water Quality Report 2023 – 2024

Orange County Health Care Agency (OCHCA) | May 30th, 2025

The 2023-2024 Ocean, Harbor and Bay Water Quality Report provides updated data on sewage spills, the spill impacts resulting in ocean water closures and an analysis of ba

The 2023-2024 Ocean, Harbor and Bay Water Quality Report provides updated data on sewage spills, the spill impacts resulting in ocean water closures and an analysis of bacteriological water quality data collected at Orange County’s (OC) ocean, harbor and bay waters.

Off-Lake Sources of Airborne Dust in Owens Valley, California

National Academy of Sciences (NAS) | June 17th, 2025

Since 2017, the District has used additional information to attribute PM10 exceedances to specific sources within the Owens Valley Planning Area. This information include

Since 2017, the District has used additional information to attribute PM10 exceedances to specific sources within the Owens Valley Planning Area. This information includes particulate and meteorological data, modeling, cameras, field observations, and media reports of dust storms. These data are compiled into the District’s exceedance database. Based on these data, the District classifies each exceedance as one of the following: 1) dust—primarily on-lake sources, 2) dust—primarily local off-lake sources, 3) dust—primarily regional event, 4) wildfire smoke, or 5) mixed—dust and wildfire sources.

Oil, Food, and Water: Challenges and Opportunities for California Agriculture

Pacific Institute | December 1st, 2015

A new comprehensive study by the Pacific Institute  sheds light on the risks posed when oil and gas exploration and production operate alongside agriculture. “There

A new comprehensive study by the Pacific Institute  sheds light on the risks posed when oil and gas exploration and production operate alongside agriculture. “There is growing concern about competition for land and water, and the impacts of soil and water contamination on the food supply and health and safety of farmworkers and consumers,” said Matthew Heberger, the study’s lead author. The disposal of oil and gas wastewater, which contains harmful chemicals, is a particular concern for agriculture. Disposal in unlined percolation pits poses a significant risk of contaminating groundwater resources that may, in turn, be used by agriculture. While this practice has been banned in several states, it is still widely used in California’s Central Valley, one of the nation’s most important agricultural regions. There are also serious deficiencies in the way California regulates the underground injection of wastes – current practices are not sufficiently protective of freshwater aquifers that may be used as drinking water or to irrigate crops and water livestock.

Ojai Basin Groundwater Management Agency Groundwater Management Plan – 2018 Update

Ojai Basin Groundwater Management Agency | August 30th, 2018

In September, 2014, Governor Jerry Brown signed into law a package of three bills (AB 1739, SB 1168, and SB 1319) known as the Sustainable Groundwater Management Act (“

In September, 2014, Governor Jerry Brown signed into law a package of three bills (AB 1739, SB 1168, and SB 1319) known as the Sustainable Groundwater Management Act (“SGMA”). SGMA provides a framework for sustainable management of groundwater supplies by local authorities, with a limited role for state intervention only if necessary to protect the resource.  The Act requires the formation of local groundwater sustainability agencies that must assess conditions in their local water basins and adopt locally-based management plans. SGMA provides local agencies with the tools and authority to require registration of groundwater wells, measure and manage extractions, require reports and assess fees, and request revisions of basin boundaries, including establishing new subbasins.  High- and medium-priority basins, as defined by the State of California Department of Water Resources (“DWR”), must adopt groundwater sustainability plans within five to seven years, depending on whether the basin is in critical overdraft. Statewide groundwater basins are prioritized based on eight criteria: (1) overlying population, (2) projected growth of overlying population, (3) public supply wells, (4) total water wells, (5) overlying irrigated acreage, (6) reliance on groundwater as the primary source of water (7) impacts on the groundwater, including overdraft, subsidence, saline intrusion, and other water quality degradation, and (8) any other information determined to be relevant by the DWR.  Consistent with its Enabling Legislation, the Ojai Basin Groundwater Management Agency (“OBGMA” or “Agency”) has worked to preserve the quantity and quality of groundwater in the Ojai Valley Groundwater Basin (“Ojai Basin”) for sustainable long-term use since the agency’s establishment in 1991. (The Agency’s Enabling Legislation, SB 534, approved by the Governor October 8, 1991, is also referred to herein as the “OBGMA Act.”) These management efforts have resulted in the protection and maintenance of the long-term water supply for the common benefit of all water users in the Basin. As a result, the Ojai Basin has operated within its “sustainable yield” for the past several decades with no evidence of “undesirable results.”  Per OBGMA Resolution No. 2014-4, adopted by its Board of Directors on December 4, 2014 (copy included as Appendix A), OBGMA is designated as the Groundwater Sustainability Agency (“GSA”) for the Ojai Groundwater Basin. In addition, SGMA identifies OBGMA as an “exclusive local agency” within its statutory boundaries for purposes of implementing the requirements of the Act. (Water Code § 10723(c)(1).) Since OBGMA, in compliance with its Enabling Legislation, already performs many of the planning and management tasks required by SGMA, and sustainable conditions have persisted in the Basin for more than a 10-year period. OBGMA determined it would comply with SGMA by making the Alternative Demonstration of groundwater sustainability authorized by Water Code § 10733.6(b)(3).  To comply with SGMA, OBGMA issued its December 23, 2016 “Report Supporting Alternative Demonstration Made Pursuant to Water Code 10733.6(b)(3). The report contained a physical description of the Basin, including groundwater levels, groundwater quality, information on groundwater-surface water interaction, data on historical and projected water demands and supplies, monitoring and management provisions. The report demonstrated how the Ojai Basin has operated within its “sustainable yield” for the past several decades with no evidence of “undesirable results.”  In sum, OBGMA’s management of the Basin pursuant to its Enabling Legislation has allowed the Agency to make the Alternative Demonstration authorized by SGMA. This 2018 Update to the Agency’s Groundwater Management Plan, undertaken in compliance with its Enabling Legislation, is part of the Agency’s ongoing efforts to preserve the long-term quantity and quality of groundwater in the Ojai Basin for the common benefit all users in the Basin. 

Old and Middle River Flow Review: USGS Gauge Readings versus Index Calculations for 2011 through 2017

California Department of Water Resources (DWR) | November 17th, 2017

This report will demonstrate the strong flow correlation between the United States Geological Survey gages at the Old and Middle Rivers (USGS OMR), and the OMR Index calc

This report will demonstrate the strong flow correlation between the United States Geological Survey gages at the Old and Middle Rivers (USGS OMR), and the OMR Index calculations, which have been used by the State Water Project and the Central Valley Project (the Projects) to operate to, and comply with, Old and Middle River (OMR) flow requirements. The results of the two different methodologies for determining OMR will be compared with daily, 5-day average, and 14-day average values, and will demonstrate a close correlation and tracking between the two methodologies. The time-span will be from December to June of the Water Years 2011 to 2017 and gives a background view and general effectiveness of using the OMR Index. The difference between the methodologies is that the USGS OMR values are based on tidally filtered hourly flow values of Old and Middle Rivers near Bacon Island, whereas the Index methodology uses an empirical equation based on net flows into and out of the Southern Delta. The USGS OMR flow values have been difficult for the Projects to operate to, in large part because the tidally filtering calculation is lagged by three days. What’s more, atmospheric conditions exert an unpredictable influence on OMR values and missing data introduces errors. By contrast, the OMR Index is much easier to work with because the San Joaquin River at Vernalis (VNS) gage used in the OMR Index equation is located upstream of the Delta and is therefore not affected significantly by tidal effects or atmospheric conditions and has only a one-day delay in the OMR Index equation. Using prior day flows from the VNS gage allows the Projects’ operations to be more predictable since current day exports can be closely controlled. Through regression analysis and empirical graphs, this report will show that the OMR Index method produces results that are closely correlated with values from the USGS OMR. And since the Index method can be used to closely approximate the USGS OMR flow values over an averaging period, the Index method is a satisfactory alternative to using the lagged USGS OMR flow data for real-time operations.

On the Connection Between Global Hydrologic Sensitivity and Regional Wet Extremes

American Geophysical Union (AGU) | October 23rd, 2018

The global water cycle is expected to intensify under climate change and can be generally characterized by greater rainfall and surface evaporation in the future. However

The global water cycle is expected to intensify under climate change and can be generally characterized by greater rainfall and surface evaporation in the future. However, the rate at which the globally averaged precipitation increases is highly variable among different climate models. In this paper, we relate the intermodel variability in global water cycle intensification to differences in model projections of heavy precipitation in tropical and some extratropical regions. We also find that models consistently experience a trade‐off between increasing heavy and decreasing light‐moderate precipitation: Models with larger future increases in heavy precipitation exhibit greater compensating declines in light‐moderate rainfall. Differences in heavy precipitation changes are also tied to model resolution. Our study helps to provide new insight on the factors shaping projections of future precipitation extremes, which have strong implications for water resources, natural hazard risks associated with flooding, and ecosystem stability.

On the dynamics of the Hadley circulation and subtropical drying

Climate Dynamics (Springer) | April 10th, 2014

Changes in subtropical precipitation and the Hadley circulation (HC) are inextricably linked. The original Halley–Hadley model cannot explain certain aspects of the Ear

Changes in subtropical precipitation and the Hadley circulation (HC) are inextricably linked. The original Halley–Hadley model cannot explain certain aspects of the Earth’s meridional circulation in the tropics and is of limited use in understanding regional changes in precipitation. Here, we expand on previous work on the regional and seasonal aspects of the HC, in particular how land–sea temperature contrasts contribute to the strength and width of the HC. We show that the Earth’s HC is well described by three regionally distinct cells along the eastern edges of the major ocean basins with opposite circulations elsewhere. Moreover, comparable summertime hemisphere cells emerge in each region. While it has been recognized that continents modify the meridional pressure gradient, we demonstrate that a substantial part of the Earth’s HC is driven by zonal pressure gradients (ZPGs) that only exist due to continental heating and air–sea interaction. Projected changes in land–sea temperature contrasts in a warming climate due to the relatively low thermal capacity of land will also affect ZPGs and thus HC strength and width, with implications for extremes in hydroclimate and freshwater resources across the increasingly vulnerable subtropics.

On the Sources of Water Supply Forecast Error in Western Colorado

American Meteorological Society (AMS) | December 1st, 2023

On-farm flood capture could reduce groundwater overdraft in Kings River Basin

California Agriculture (UCANR) | November 16th, 2016

Chronic groundwater overdraft threatens agricultural sustainability in California’s Central Valley. Diverting flood flows onto farmland for groundwater rechar

Chronic groundwater overdraft threatens agricultural sustainability in California’s Central Valley. Diverting flood flows onto farmland for groundwater recharge offers an opportunity to help address this challenge. We studied the infiltration rate of floodwater diverted from the Kings River at a turnout upstream of the James Weir onto adjoining cropland; and calculated how much land would be necessary to capture the available floodwater, how much recharge of groundwater might be achieved, and the costs. The 1,000-acre pilot study included fields growing tomatoes, wine grapes, alfalfa and pistachios. Flood flows diverted onto vineyards infiltrated at an average rate of 2.5 inches per day under sustained flooding. At that relatively high infiltration rate, 10 acres are needed to capture one CFS of diverted flood flow. We considered these findings in the context of regional expansion. Based upon a 30-year record of Kings Basin surplus flood flows, we estimate 30,000 acres operated for on-farm flood recharge would have had the capacity to capture 80% of available flood flows and potentially offset overdraft rates in the Kings Basin. Costs of on-farm flood capture for this study were estimated at $36 per acre-foot, less than the cost for surface water storage and dedicated recharge basins.