1. Detailed research into the ecological impacts of inter-basin water transfers (IBTs) is virtually nonexistent on a global scale. However, a growing awareness of the serious nature of such impacts—for example, the loss of biogeographical integrity, the loss of endemic biotas, the frequent introduction of alien and often invasive aquatic and terrestrial plants and animals, the genetic intermixing of once separated populations, the implications for water quality, the frequently drastic alteration of hydrological regimes, the implications for marine and estuarine processes, climatic effects, and the spread of disease vectors, amongst many others—demands a most urgent and world-wide appraisal of all current planning and research strategies.



2. This paper first defines the types of extant IBTs, and details some case studies for three widely separated regions of the world, namely: south-eastern Australia, southern Africa, and the central and south-western parts of the United States of America. In doing so, it highlights the chronic paucity of ecological data on their impacts, while simultaneously emphasising their extreme complexities.



3. Finally, we call for an international meeting on such schemes, as a matter of priority and extreme urgency, in order to assess the extent of IBTs, their geographical distribution, and their ecological and sociological impacts and implications.

An assessment of the ecological impacts of inter-basin water transfers, and their threats to river basin integrity and conservation

The California State Department of Water Resources and the United States Bureau of Reclamation Mid-Pacific Region have developed a general-purpose reservoir–river basin simulation model for the planning and management of the State Water Project and the federal Central Valley Project. The California Water Resources Simulation Model brings a fundamental change to modeling of these systems. Model users specify system objectives as input to the model. System description and operational constraints are specified using a new water resources engineering simulation language. A mixed integer linear programming solver efficiently routes water through the system network given the user-defined priorities or weights. Simulation cycles at different temporal scales allow for successive layering of constraints. The power and flexibility of the model is demonstrated by its ability to simulate the operation of complex new environmental water accounts.

https://www.deltarevision.com/2011videos/waterflow/CalSim%20A%20generalized%20model%20for%20reservoir%20system%20analysis.pdf

CalSim: Generalized Model for Reservoir System Analysis

1. The Sacramento–San Joaquin River Delta, a complex mosaic of tidal freshwater habitats in California, is the focus of a major ecosystem rehabilitation effort because of significant long-term changes in critical ecosystem functions. One of these functions is the production, transport and transformation of organic matter that constitutes the primary food supply, which may be sub-optimal at trophic levels supporting fish recruitment. A long historical data set is used to define the most important organic matter sources, the factors underlying their variability, and the implications of ecosystem rehabilitation actions for these sources.



2. Tributary-borne loading is the largest organic carbon source on an average annual Delta-wide basis; phytoplankton production and agricultural drainage are secondary; wastewater treatment plant discharge, tidal marsh drainage and possibly aquatic macrophyte production are tertiary; and benthic microalgal production, urban run-off and other sources are negligible.



3. Allochthonous dissolved organic carbon must be converted to particulate form—with losses due to hydraulic flushing and to heterotroph growth inefficiency—before it becomes available to the metazoan food web. When these losses are accounted for, phytoplankton production plays a much larger role than is evident from a simple accounting of bulk organic carbon sources, especially in seasons critical for larval development and recruitment success. Phytoplankton-derived organic matter is also an important component of particulate loading to the Delta.



4. The Delta is a net producer of organic matter in critically dry years but, because of water diversion from the Delta, transport of organic matter from the Delta to important, downstream nursery areas in San Francisco Bay is always less than transport into the Delta from upstream sources.



5. Of proposed rehabilitation measures, increased use of floodplains probably offers the biggest increase in organic matter sources.



6. An isolated diversion facility—channelling water from the Sacramento River around the Delta to the water projects—would result in substantial loading increases during winter and autumn, but little change in spring and summer when food availability probably matters most to developing organisms.



7. Flow and fish barriers in the channel could have significant effects, especially on phytoplankton sources and in dry years, by eliminating ‘short-circuits’ in the transport of organic matter to diversion points.



8. Finally, productivity of intentionally flooded islands probably would exceed that of adjacent channels because of lower turbidity and shallower mean depth, although vascular plants rather than phytoplankton could dominate if depths were too shallow.



Copyright © 2000 John Wiley & Sons, Ltd.

Organic matter sources and rehabilitation of the Sacramento–San Joaquin Delta (California, USA)

A review of total dissolved copper and its chemical speciation in San Francisco Bay, California

The cycling of dissolved selenium was examined in the North San Francisco Bay estuary using 5 surface water transects from the Pacific Ocean (Golden Gate) to the Sacramento and San Joaquin Rivers, monthly river sampling, and three collections of oil refinery effluents during 1997–2000. By combining these data with earlier results from the mid-1980s, a nearly 16-year record of riverine fluxes, estuarine processes, and anthropogenic inputs was obtained. The Sacramento River concentrations and speciation have remained unchanged over the period, and while the speciation of selenium in the San Joaquin is similar, its dissolved selenium concentrations have decreased by almost one half. More significantly, the concentration of selenium from oil refinery discharges to the mid-estuary has decreased 66% and its speciation changed from one dominated by selenite (66%) to one that is only 14% selenite. This change in refinery effluents occurred while our study was underway, with the result being a pronounced decrease in selenite concentrations (82%), and hence total dissolved selenium, in the mid-estuary. A companion study found that sediment/water exchange is a minor flux to the estuary, and hence selenium inputs from the Sacramento River, as well as refineries during low flow (summer, fall) periods exert major controls on the dissolved selenium behavior in this estuary. Nevertheless, in situ processes associated with organic matter cycling (photosynthesis and respiration) still modify the distributions and internal transformations of dissolved selenium, notably organic selenide.

Selenium biogeochemistry in the San Francisco Bay estuary: changes in water column behavior

This paper presents the procedures and techniques employed as part of the Bay-Delta proceedings to evaluate the water supply impacts of various proposed flow and water quality objectives for the Delta. The primary tool selected for analyzing the impacts was DWR's Planning Simulation Model. A number of alternative objectives to protect various beneficial water uses were proposed by the Board in their plan. Simulation studies were formulated and conducted to analyze the proposed objectives individually and in combination. Impacts were examined by comparing study results with a base study using current Delta flow and salinity requirements. The CVP-SWP system was used as a surrogate to the whole system to evaluate overall water supply impacts. These impacts could then be used to evaluate the relative benefits or trade-offs of proposed changes in Delta flow or water quality objectives. This process brought various water interests together so that agreement on technical methodology could be used as a basis for reaching a clearer understanding of statewide impacts of proposed Delta water quality plans.

George W. Barnes

Papers

Water Supply Impact Analysis of Proposed Water Quality Control Plan for Salinity for San Francisco Bay and Sacramento-San Joaquin Delta Estuary