WSP08301

• File Number: 8273.100.50
• Description: Colorado River Basin Salinity Control - Federal Agency Reports - BOR
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 2/1/1988
• Title: Estimating Economic Impacts of Salinity of the Colorado River - Final Report - February 1988
• Water Supply Pro - Doc Type: Report/Study

Salinity in the Colorado River Basin 21

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Table 4. - Current or estimated TDS levels 01 M&I water supplies
In the Lower Colorado River Basin.

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O'.l
CO
CO'.

MetrQPolttan Area IQ.S
San Diego County * 1986 estimated blend 579
(90% from MWD)
Riverside Co. * 1986 estimated blend 535
Orange County * 1986 estimated blend 505
San Bernardino * 1986 estimated blend 455
Los Angeles * 1986 estimated blend
City/County average 405
Phoenix CUrrent valley average 400-500
Tucson current valley average 400.500
Las Vegas valley 1986 groundwater 235-250 **
1986 Colorado River actual 542
1986 blend 517 **

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* Does not InclUde those portions 01 the County outside the MWD service areas.
More recent numbers are 310 and 499, respectively, but they were not available
when the computer program was developed.

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causing rccord low salinity levels. As the river
returns to more normal flows, the TDS at Parker
should return to around 700 mgiL.

The current TDS averages make it clear why
San Diego, Riverside, and Orange Counties in
southern California are the three areas most ac-
tively concerncd with salinity. There are other
areas or subareas that have higher and much
higher average TPS levels (such as Buckeye and
parts of Chandler, Arizona), but Riverside and
Orange Counties are part of a major metropoli-
tan area as well as part of the Santa Ana River
watershed which exhibits substantial incremental
salinity as it reacbes Orange County. Further,
the Santa Ana Region Water Quality Control
Board has established firm policies on salinity
which have mandated both structural and

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management actions on the part of area water
suppliers. The responses of Riverside and
Orange Counties to increasing salinity can serve
as a general model for future activities in other
areas of the Lower Colorado River Basin.

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Salinity, as this report discusses, is an
economic water quality issue- not a matter of
serious concern for human bealth. In this sense
salinity becomes a water quality parameter that
is subject to policy and cost decisions uolike the
decisions mandated by the presence of TCE or
nitrate poUution exceeding primary drinking
water standards. The fact that salinity is pri-
marily a management problem may also explain
why so little regulatory concern has yet been
cxhibited by cities and slates in regularly
measuring or addressing TDS in water supplies.