The Salinity of Rivers

Scientific American | July 1st, 1981

Many ancient civilizations rose by diverting rivers and irrigating arid lands to grow crops. For such projects to succeed human beings had to learn to work cooperativ

Many ancient civilizations rose by diverting rivers and irrigating arid lands to grow crops. For such projects to succeed human beings had to learn to work cooperatively toward a common objective. The most fruitful of the ancient systems was created at the southeastern end of the Fertile Crescent, the broad valley formed by the Tigris and the Euphrates in what is now Iraq. From there civ il ization spread eastward through present-day Iran, Afghanistan, Pakistan, India and thence into China, wherever rivers disgorged through valleys of recently deposited alluvial soil. At its peak of productivity each irrigated region probably supported well over a million people. All these civilizations ultimately collapsed, and for the same reason: the land became so salty that crops could no longer be grown on it. The salts that were washed out of the soil at higher elevations became concentrated in the irrigated fields as the water evaporated from the surface and transpired through the leaves of the growing crops. Although floods, plagues and wars took their toll, in the end the civilizations based on irrigation faded away because of salination.

The San Francisco Bay-Delta Agreement: Principles for Agreement on Bay-Delta Standards Between the State of California and the Federal Government

California State Water Resources Control Board (SWRCB) | December 15th, 1994

The Status of Rainbow Trout (Oncorhynchus mykiss) in the Stanislaus River Summary report of 2015 snorkel surveys

Delta Stewardship Council (Delta Council) | August 1st, 2016

The tradeoff between water savings and salinization prevention in dryland irrigation

Advances in Water Resources (Elsevier) | December 7th, 2023

Soil salinization is a global phenomenon that affects large tracts of arid farmland worldwide. It contributes to the loss of soil fertility, declining yields, and – in

Soil salinization is a global phenomenon that affects large tracts of arid farmland worldwide. It contributes to the loss of soil fertility, declining yields, and – in the most severe cases – land unsuitability for cultivation. Irrigation water applications are both the main cause of and the solution to, anthropogenic (or ‘secondary’) salinization because salt typically enters the soil column as dissolved in irrigation water and leaves it through excess water applications (e.g., leaching). Excess leaching, which places additional water costs in areas affected by water scarcity, can be achieved with different irrigation techniques and practices. Here, by complementing a process-based crop water model with a salt balance of the shallow soil, we investigate the tradeoff between root zone salinization and water conservation to limit withdrawals from the water source. We evaluate how such a tradeoff is achieved under different irrigation technology and excess leaching practices. Considering as a case study the cultivation of tomatoes in Egypt, we find that drip and furrow irrigation allows for better control of salt accumulation, thus preventing crop exposure to salt stress. Drip irrigation achieves this goal with minimal water applications because it maintains the soil wetter. Thus, the (rare) rainfall events find more suitable conditions to drain the excess moisture. Conversely, by using more irrigation water (and ‘less efficiently’), furrow irrigation allows for higher rates of soil drainage and salt leaching. The irrigation schedule typically adopted with sprinkler irrigation allows for soil drying, thus limiting the ability of rainfall events to drain the soil and leach its salts. Collectively, these results highlight the key role of irrigation technology and practices in the management of secondary salinity in dryland agriculture. Specifically, there is a tradeoff between minimizing water use and preventing salt accumulation in the root zone. Drip irrigation exhibits the co-benefit of achieving both goals, while furrow irrigation limits soil salinity at the cost of requiring greater volumes of applied irrigation water.

The Use of Smolt Survival Estimates to Quantify the Effects of Habitat Changes on Salmonid Stocks in the Sacramento-San Joaquin Rivers, California

Canada Department of Fisheries and Oceans (DFO) | July 1st, 1989

The Vernalis Adaptive Management Program (VAMP): Report of the 2010 Review Panel

California State Water Resources Control Board (SWRCB) | May 11th, 2010

Panel members were asked by the Delta Science Program to carry out an independent review of a 12-year VAMP (Vernalis Adaptive Management Plan) experimental program design

Panel members were asked by the Delta Science Program to carry out an independent review of a 12-year VAMP (Vernalis Adaptive Management Plan) experimental program designed to develop water management measures that would provide protection to juvenile Chinook salmon migrating through the San Joaquin River system and associated Sacramento-San Joaquin River Delta (Delta) waterways. The Charge to the Panel was expressed as a series of three questions that the Panel was obligated to address: 1) Do the results to date from the VAMP study provide useful scientific information about the relationship between salmon survival and each of the following factors: Flows, Exports, and Barrier installation at the head of Old River? 2) How can the results from the VAMP to date be used to inform the State Water Resources Control Board's (SWRCB) current efforts to review and potentially revise the San Joaquin River flow objectives and their implementation? 3) How can the experiences to date from the VAMP study be used in a scientific manner to inform future monitoring and study efforts related to determining appropriate flow, operational, and water quality requirements to protect San Joaquin River fisheries (specifically Chinook salmon and steelhead)?

The vertical distribution and biological transport of marine microplastics across the epipelagic and mesopelagic water column

Nature Portfolio (Springer Nature) | July 6th, 2019

Plastic waste has been documented in nearly all types of marine environments and has been found in species spanning all levels of marine food webs. Within these marine en

Plastic waste has been documented in nearly all types of marine environments and has been found in species spanning all levels of marine food webs. Within these marine environments, deep pelagic waters encompass the largest ecosystems on Earth. We lack a comprehensive understanding of the concentrations, cycling, and fate of plastic waste in sub-surface waters, constraining our ability to implement effective, large-scale policy and conservation strategies. We used remotely operated vehicles and engineered purpose-built samplers to collect and examine the distribution of microplastics in the Monterey Bay pelagic ecosystem at water column depths ranging from 5 to 1000 m. Laser Raman spectroscopy was used to identify microplastic particles collected from throughout the deep pelagic water column, with the highest concentrations present at depths between 200 and 600 m. Examination of two abundant particle feeders in this ecosystem, pelagic red crabs (Pleuroncodes planipes) and giant larvaceans (Bathochordaeus stygius), showed that microplastic particles readily flow from the environment into coupled water column and seafloor food webs. Our findings suggest that one of the largest and currently underappreciated reservoirs of marine microplastics may be contained within the water column and animal communities of the deep sea.

The Water Quality Control Plan (Basin Plan) for the Sacramento River and San Joaquin River Basins Fifth Edition

Central Valley Regional Water Quality Control Board (CVRWQCB) | May 31st, 2018

The preparation and adoption of water quality control plans (Basin Plans) is required by the California Water Code (Section 13240) and supported by the Federal Clean Wat

The preparation and adoption of water quality control plans (Basin Plans) is required by the California Water Code (Section 13240) and supported by the Federal Clean Water Act. Section 303 of the Clean Water Act requires states to adopt water quality standards which "consist of the designated uses of the navigable waters involved and the water quality criteria for such waters based upon such uses." According to Section 13050 of the California Water Code, Basin Plans consist of a designation or establishment for the waters within a specified area of beneficial uses to be protected, water quality objectives to protect those uses, and a program of implementation needed for achieving the objectives. State law also requires that Basin Plans conform to the policies set forth in the Water Code beginning with Section 13000 and any state policy for water quality control. Since beneficial uses, together with their corresponding water quality objectives, can be defined per federal regulations as water quality standards, the Basin Plans are regulatory references for meeting the state and federal requirements for water quality control (40 CFR 131.20). One significant difference between the state and federal programs is that California's basin plans establish standards for ground waters in addition to surface waters. Basin Plans are adopted and amended by Regional Water Boards under a structured process involving full public participation and state environmental review. Basin Plans and amendments thereto, do not become effective until approved by the State Water Resources Control Board (State Water Board). Regulatory provisions must be approved by the Office of Administrative Law. Adoption or revision of surface water standards are subject to the approval of the U.S. Environmental Protection Agency. Basin Plans complement water quality control plans adopted by the State Water Board, such as the Water Quality Control Plans for Temperature Control and Ocean Waters. It is the intent of the State and Regional Water Boards to maintain the Basin Plans in an updated and readily available edition that reflects the current water quality control program. This Basin Plan covers the entire Sacramento and San Joaquin River Basins. A separate Basin Plan covers the Tulare Lake Basin. The Basin Plan was first adopted in 1975. In 1989, a second edition was published. The second edition incorporated all the amendments which were adopted and approved since 1975, updated the Basin Plan to include new state policies and programs, restructured and edited the Basin Plan for clarity, and incorporated the results of triennial reviews conducted in 1984 and 1987. The Third Edition - 1994 incorporated all amendments approved between 1989 and 1994, included new state policies and programs, edited and restructured the Basin Plan to make it consistent with other regional and state plans, and substantively amended sections dealing with beneficial uses, objectives, and implementation programs. The current edition (Fourth Edition - 1998) incorporates two new amendments approved since 1994. One amendment deals with compliance schedules in permits and the other addresses agricultural subsurface drainage discharges. In this Basin Plan, "Regional Water Board" refers to the Central Valley Regional Water Quality Control Board and "State Water Board" refers to the State Water Resources Control Board. Appendix Updates and amendments  are at the State Water Board "Basin Plan" page

Thermal performance in juvenile hatchery Oncorhynchus tshawytscha: aerobic scope tests over a range of environmental temperatures

U.S. Environmental Protection Agency (EPA) | March 15th, 2016

In heavily-altered ecosystems, anthropogenic factors coupled with global climate change have drastically changed available habitats for many native fishes (Cloe

In heavily-altered ecosystems, anthropogenic factors coupled with global climate change have drastically changed available habitats for many native fishes (Cloern and Jassby 2012, Moyle et al. 2013). Water projects such as large hydropower dams have altered flow and temperature regimes (Poff et al. 1997, Bunn and Arthington 2002, Marchetti and Moyle 2001), and reduced or degraded native spawning and rearing habitats (Sheer and Steel 2006, Pelicice and Agostinho 2008), while global climate change has resulted in warmer overall river temperatures (Cloern and Jassby, 2012). As ecologically relevant environmental variables like temperature have shifted, fish populations have subsequently declined (Cloern and Jassby, 2012; Hanak et al., 2015). Native California fishes have been disproportionately affected by these changes, and precipitous population declines have been observed for several species, some of which are listed under the Endangered Species Act (ESA) (Moyle et al. 2013). Despite documented correlations between fish declines and changes in environmental variables such as temperatur e (Moyle and Leidy, 1992; Moyle et al. 2010; Quiñones and Moyle 2014), there has been a profound lack of data available on the actual physiological and/or behavioral mechanisms driving fish population declines. Physiological performance data, such as information on aerobic scope, may help provide mechanistic explanations for both how and why fish population declines are occurring. Furthermore, as populations decline and management becomes more crucial for population persistence, thermal limits, optimal thermal ranges, and data on how key physiological processes, such as metabolic rate, change in response to environmental variables becomes more important. Therefore, the objectives of our study were to quantify the aerobic scope of juvenile Chinook salmon ( Oncorhynchus tshawytscha) acclimated to two different rearing temperatures (14 or 20 °C) and tested over a temperature range of 12-26°C.

Time-lagged impacts of extreme, multi-year drought on tidal salt marsh plant invasion

Ecological Society of America (ESA) | June 11th, 2020

Climate change is projected to increase the frequency of extreme drought events, which can have dramatic consequences for ecosystems. Extreme drought may interact with o

Climate change is projected to increase the frequency of extreme drought events, which can have dramatic consequences for ecosystems. Extreme drought may interact with other stressors such as invasion by non-native species, yet little research has explored these dynamics. Here, we examine the physical mechanisms and temporal scale underlying a dieback of an invasive non-native plant, Lepidium latifolium, in tidal salt marshes of the San Francisco Bay, California, USA, during an extreme, multi-year drought occurring from 2012 to 2015. Using generalized additive mixed models (GAMMs), we explored the relationship between eight years of estuarine salinity data and five years of L. latifolium density data from three marshes spanning a gradient of salinity across the San Francisco Bay. We found a significant time-lagged (3 yr) effect of estuarine salinity on L. latifolium density, with high salinities preceding reductions in L. latifolium densities and low salinities preceding increases. The most dramatic change in stem density, a 54% reduction in 2015, was preceded by a salinity increase of 43% from 2011 to 2012. We found the L. latifolium decline was driven by impacts on mature, rather than young, plants. Additionally, we tested the importance of local precipitation in driving L. latifolium densities in a one-season rain exclusion experiment. We found 100% exclusion of precipitation during one rainy season (January–mid-May) did not have a significant impact on densities of mature stands of L. latifolium. Our finding that estuarine salinity was a key driver of L. latifolium invasion dynamics suggests sea level rise, like extreme drought, may hinder L. latifolium invasion, as it will also raise estuarine salinities. Further, our study highlights the importance of temporal lags in understanding climate change impacts on biological invasions, which has received very little study to date.