WSP07432

• File Number: 8270.100
• Description: Colorado River Basin Water Quality/Salinity -- Misc Water Quality
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1997
• Author: USDOI
• Title: Quality of Water - Colorado River Basin - Progress Report No. 18 - January 1997
• Water Supply Pro - Doc Type: Report/Study

SUMMARY

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The Qua/a,' of H'arer, Colorado R/I'er Baslfl, Progn'SJ Report IS prepar~d every:! yean. to
~Umman7e the ~[.Jtu, of W;;ller qUJ.ht) In the COIOf;]do River Basin The Colorado Rl\"t:'f and Its
tnbutancs pro\ide municIpal and mdustn:.!.] water for more than] S million people in the ;,e\"en
Basin StJ,tc, anJ Irrigation ....Jler to nearly J million acres of land. The threat of sJ[mity is J
major concern In both the l:mted S{;lte~ and the Republic of ~te:\]co. Increases In salmity Me
ImpOnant In the Colorado RIver BaSin becau"c of its dfect on crop" md on mUnicipal and
InJustnal users Damages In the L:pper Basin and ~Iexico are unquanllfied, but"damages In the
Lower Basin ha\t' im:rea~ed to about $750 million ~r year

The Colorado RIver BaSin Salinity Control Act (Salin!!)' Control Act) (Public Laws [PL.] 93-320.
98-569. and 104-~01 authonzes the Secretaries of the U.S. Department of the Intenor (interior) and
U.S Departmenl of Agnculture ({.iSDAl 10 enhance and protect Ihe quality of water availabh.' in
the Colorado River for use m the L'nlled State~ and the Republic of \1e.\ico.

Title I of the Salmity Control Act authorizes the construction and operatIon of a desalllng plant.
brine dl~chargc canal. and other features to en;]ble the Unlled Slates 10 ddiver water to \le,ico
havmg an average ,alinity no greater than 115 parts per mtlilon (ppml +/- 30 ppm over the annual
average salmity of the Colorado River at Imperial Dam.

In addItIOn 10 eariler. unit-specific authrorities provided under Title II of the Salinity Control Act.
PL. 1()..1~20 authorize') the Secretary of the Intenor 10 Jmplement a ne....... basinwide J.pproach to
salinity control. Although ongmally authorized:is a separate program. P.L. 1()..1-127 authonze~
the Secretary of Agriculture 10 Implement salinity control measures as part of the USDA's
En\-Jronmental Quality Incentives Program,

The 1996 Rene"'. Water Qualir... Standards for Salinity. Colorado Ri\.u SYSTem found that the
"tlow-adJu,ted" salmity levels at the Hoover. Parker. and Imperial Stalions were above lhe numeric
cmena le\'els of the salimty slandards discussed in chapter 6_ ..F1o.......adJusted.. salinilY represenls
the salmity that ......ould be e'pected under normal (average) now condHlOns In the river.
Fortunatel)-. the observed salinil)' levels conllnue to be belo...... lhe numeric cmena because of
e,\istlng: controls (621AOO Ions per year) and bvorable hydrologic conditions. However. once the
Impacts of recenl waler developments work Ihelr way down lhrough the reservOir system. salinilY
levels are e_\pected to e.\ceed the numeric cntena by ..n8.~OO tons per year.

Reclamalion eSllmales that nearly 1.5 million tons of salt per year will need to be remo'.-ed from
the nver system by 2015 to maint.1in average salinity below the numenc criterion level of
879 milligrams per liter (mgIL) at Impenal Dam. Even with thes.e controls in place. there will
,till be temporal")' excursions above the numeric cntenon of 879 mgIL due 10 the natural variations
in climJ.tic conditions. hydrology.. and water usage.

The Salimt) COnlrol Act directs the Secrelal)' of the Interior to implement units based on cost
effectiveness (COSI per Ion of salt removal). The umts under construction wllhm the Bureau of
Reclamation (Reclamation) program are neanng complellon and will have an average cost
effectiveness of S7J per ton. The U.S. Department of Agricuhure program has averaged S...t...t per
ton through 199...t. 8mh programs h;nt" been \el")' dfecllve a.nd complement each other wllh