WSP10002

• File Number: 8270.100
• Description: Colorado River Basin Water Quality/Salinity -- Misc Water Quality
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/1/1989
• Author: USDOI
• Title: Quality of Water - Colorado River Basin - Progress Report No. 14 - January 1987
• Water Supply Pro - Doc Type: Report/Study

suggests the dedin€' ot salinity "oncen'ril.liQn<; may h<l'/€ he"'n in part r<lIIS".-j
by the transition f1"om a telativ~dy drier period (1055-65) "w'ilh ,111 _Hlnllcd
vir~in (unr1eplt"ted) fl.,.... of 13.23 ",illian acre-f"'Pt ;p L€'l?'5 Fen\'. t.., .f
telativel:; :,..'ptter period (19fJ5 75) '.'jlh;1Il <lnll'Jal ':il.';'111 fIr,... "f h.1f) miJlj"n
acre-feet. This is an increase in the tlw.' 0f arrln:~im,pply In PPI '-,tJf "1<1 "',~.
be responsible for a por~ion of the d€u"'A:O::~ ill "hE' s.llinl", r:nnr-t'ntlHj"n
observed at I~pel ial Dam.

~
r.:::
'1
r..

The ":lore tecellt period (l'l8~ A7) ':.15 e'.'pn '!lOle extreme, '.dth :';omE
flo'_'s ':ell above rhose e....er lecorrieri. This "_';j~ proh<lbl,v the majol L,W"e at
the near 200 mg/L drop in salinity o'/I='r the Llst fe".. :.'''''U'';. ;. n,1fISlic<l1
analysis r)f the CRSS projec':ons for salinir:. indicat""s tha! ';illinit"l '.'ill
usually l.ange bet'.'een 64":' and l,n..... "!g, L. 'w'i th an aVE'lage ot 8Jo m~/L lrndel
the present le'.el of de\'t:'lopmellt; ho'."e...er. ahout 5 pelC~n( of the time
salinity could ~ary outside this range, as it did in 1986 ~ith a salinity of
577 mg/L.

2. Reservoir Effects

One of the most significant ch,:lIlges '..hich h~s Or:clltrerj to th~
salinity of the Colorado Ri'/fOr is due to the IP~ndation of the n",tut-al fIn\,! of
the rivet basin. One study 13/ sho....s that stol<\lZ:e in Lake rn1.rell reduced the
month-to_month '/ariiltion from thE' mean salinit\! hplo'.r r.len Can:..rnn [),~m frr)m 2')0
mg/L to 72 mg/L. This is leadily apparellt in a plot of tile data, Figure V-J.

"00
1300
I~OO
1'00
-
"- 1000
.
- gOO
-
?; 800
700
- 600
.
~
500
'00
30e
:00

. .
. : . :'. :'.'
~ ,.... . '. ~ . '. ... .. ..
'.:-- ,. .".
.. '. .'... .....
. . ". ..... '.:.. , ..,
.... '. "': '. :-:.. .' .' , ....
. . . ~.. ." .:." .
':,." ., '.. No'
..' .

'.

. .
,,( ,: t,
'., ;-:.::....\.... U/~..~
(, . """...,\~ . .
, tJ... '..to
. ',..."

'.

.

'.

.

.
.
.
'.

. .
....
.
....
.

.

. .

. .
. ...
',' .

. .

'.
.'
.. .

.

-
,

.

..
.'

.

19"0

1950

1960

l-~:O

'980

1990

You

Figure V-J, Monthly salinIty belo1.r Lake Po~ell (l~~l 8'l.

The period of P63-80 reptesents the ~OSt significant period of
reservoir storage in the history of ':ater de.....elopment on the Colorado River.
Storage in F'laming Gorge Reser','oir. Laloe Po....ell. and Lake Mead increaseci froltJ
less than 20 million acre-feet in 1Q63 to o,'er 50 million acre-feet by IQ8f).
The spill of Glen Canyon Dam in lQ80 ended the initial filling of the major
reservoirs on the Colorado Ri',er. "'ate. ':hich 'w'as being used to fill the

'i-3