Salinity Management - an emerging issue related to salt increases in our water resources. As the population increases and the amounts of our higher-quality water supplies stabalize or decline, water supplies with marginal water quality/higher salt contents become more economical for use. The salt content continues to increase in our imported water supplies, our groundwater basins, and our treated wastewater before disposal to the environment.

It is a domino effect. As Southern California is located "at-the-end-of-the-pipe" for imported water supplies from the distant Colorado River and the San Francisco Bay-Delta/State Water Project sources, upstream water users continue to increase the salt content for water consumers in our area. This water is used along with the local surface water supplies to recharge the large groundwater basins after treatment through local wastewater treatment plants. Groundwater is pumped with the increasingly higher salt content and used by consumers followed by furter local wastewater treatment and disposal downstream, with likely ultimate disposal to the ocean through an ocean outfall pipeline several miles off the California coastline. This is how most of the major metropolitan areas in coastal Southern California manage wastewater disposal.

Areas further from the coast and the desert have greater wastewater disposal problems. For example, our neighbors in the major cities in Arizona need to closely manage salts in wastewater disposal to minimize damage to the ecologies in streambeds and quality of groundwater supplies.

Desalting Plants & Brine Lines
One solution to this salinity management problem is to build and operate sets of local water and wastewater treatment plants that purify water and concentrates the remaining brine water. The purified water to be used by consumers. The brine water disposed of through regional/watershed brine-disposal pipelines all the way to ocean outfall pipelines. Great advances have been made in the design and operation of desalting plants over the last few years due to membrane technologies that effectively filter salts from water at increasingly lower costs. This includes the familiar reverse osmosis technology with more efficient and durable membranes and coarser-filter membranes such as microfilters, nanofilters and ultrafilters. The cost for construction and operation of plants with membrane technologies are declining due to higher demand and competition. The cost for these facilities remains high relative to the alternative cheaper supplies of imported water and groundwater with little or no treatment.

Salinity Management Coalition
The urgency for Southern California to build and operate more desalting plants and brine lines is rising. An informal coalition of groups representing smaller water and wastewater agencies has been meeting regularly since 1999 to discuss the problem of salinity and how to manage it better. This "Salinity Management Coalition" is presently composed of representatives from the Association of Ground Water Agencies (AGWA), the Metropolitan Water District of Southern California (Met), the Southern California Affiliation of Publicly Owned Wastewater Treatment Plants (SCAP), and the WateReuse Association. Progress is continuing through working meetings and outreach efforts such as this web page and obtain a consensus on how to proceed.

Federal Legislation for the Salinity Problems
It appears one effort should be to establish federal legislation for salinity management. This would include identifying an appropriate federal agency or department that can adminster and prioritize grant funding for the desalting plant and brine line projects throughout the western and southern states. Preliminary estimates on the cost for projects anticipated to be needed in Southern California alone within the next 20 years is about $20 billion.

This page will be developed further with specific links to other sites and information related to salinity problems and solutions. Forward links and information to Kelly Rowe.

Salinity Management Study

The US Dept. of Interior - Bureau of Reclamation (Bureau of Rec) and the Metropolitan Water District of Southern California (Met) completed a report, dated June 1999, entitled "Salinity Management Study". This study is the culmination of several years of work evaluating the needs to manage the problem of increasing salts in our water resources of Southern California. Key points from this report will be described below.

Electronic copies of this 1999 "Salinity Management Study" is provided through the following links as PDF format files. They are rather large and are broken into several files. Not all figures from the report are included as figure files generally consume large space.

Final Report (2.3 MB)
Table of Contents for Appendices (12 KB)
First Part of Appendices (2.3 MB)
Second Part of Appendices (1.2 MB)

 

The figure above shows Metropolitan's general plan for blending water from the two major sources of imported water supplies, Colorado River Water and State Water Project Water from the San Francisco Bay-Delta area. Metropolitan attempts to deliver water with a salt, or total dissolved solids (TDS), content of 500 mg/l or less.

It is common for Colorado River Water to have a TDS content over 500, perhaps over 700 mg/l, especially during years with low river flows.

State Water Project Water has generally low TDS content water, but is more variable, from low to high, depending upon the time of year and the pumping pattern for exporting water south of the SF Bay-Delta.

As the grey area shows the southern half of the Metropolitan service area gets a blend of water from the two sources. As there is more Colorado River water in the blended supply it has a higher salt/TDS content than the unblended supply areas.

This figure shows the peril of potentially pumping saline water into the State Water Project California Aqueduct, to deliver water to over 25 million Californians, as the intake pumping stations are located near the mouth of the San Francisco Bay-Delta. During high tides with low freshwater outflow the seawater prism may advance inland. Global climate change computer models predict California may have more precipitation, but as it will be warmer there will be less snow-more rain and a shorter runoff period. Historical records of flows for the San Joaquin and Sacramento Rivers over the last 100 years show a trend in declines of flow during the April to July period of major pumping/export of water to areas south of the San Francisco Bay-Delta area. (Figure from "Climate" web page.) It can be expected in the next few decades that the saline front may move to these important pumping plants for exporting water out of this area.

For decades it has been recognized by people in many state and federal agencies that the intakes for pumps for the State Water Project (SWP) and the Central Valley Water Project are located too close to the mouth of the SF Bay-Delta. The "Peripheral Canal", an important element of the "State Water Plan" prepared during Governor Pat Brown' tenure, was suppose to solve the problem of potentially pumping saline water in the delta. The location for the "Peripherial Canal" was planned to be on the east side of the delta area, upgradient of the major agricultural areas and urban sewer/wastewater treatment plant disposal points. Much higher quality water would be obtained for use in the State Water Project and the federal Central Valley Project. The water from these projects are supplied to citizens in the southern and western portions of the San Francisco Bay area as well as those in the "Southern Californa" area.

The state initiative to fund the Peripheral Canal was defeated by voters in 1982. Political reluctance to proceed with another initiative for this project has pointed to this defeat. However, it is likely voters in the San Francisco Bay area, who now unknowingly use water supplied by the State Water Project and Central Valley Project, in the near future will experience more cut-backs in water use and poorer water quality. Once they understand they are tied to the same water supplies in the South SF Bay area as in the LA area an initiative for constructing the Peripheral Canal, as originally envisioned, will be successful. This is a powerful constituency totaling about 25 million out of currently 35 million Californians.

The exact timing for a new Peripheral Canal initiative will depend upon a number of factors. The main factors will likely be the precipitation patterns, as in experiencing several drought years, and problems with maintaining the ecosystems in the San Francisco Bay-Delta area. Low flows of fresh water flowing through the delta will increase the salt content of exported water supplies. The endangered species issues in this area will always be used as a trump card over the operations of the large pumps moving water supplies to the majority of California's citizens. These are certainly not simple issues. Long-term solutions to meet the Bay-Delta water management goals are the basis for the CALFED program. Good political and bureaucratic leadership at the local, state and federal levels is continuously needed to advance the CALFED goals. Governor Davis' and Secretary Babbit's "Framework for Action" signed in June 2000, appeal to all of the stakeholders, but neither are they all happy with it. Perhaps that is the best solution, in the meanwhile...