7625

• UCREFRP Catalog Number: 7625
• Author: Stone, R. C., L. Fields and K. Miller.
• Title: Lake Powell Post Impoundment Investigations.
• USFW Year: 1964.
• USFW - Doc Type: Progress Report No. 2,
• Copyright Material: NO

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Tr.ese are presented as best illustrating a nur::ber of co~d.:. ticns U::G ~'~y nc'~

-)-

shG'..r the :TF1Xi::ium develo'::;l:1e8t of a:1Y r,:u''c,icular or.e.

Resul ts obtabed duri.ng this seC::s,n':. year and in lSX33 i::dicClt0 :.hat

Lak.e Po',fell has been eS3entially a :.1cnomictic} negative heterogr2.::ie l:J.ke

duri:ig its early life. The reservoi:- s!,o'.-iS gO'Jd su::u-:Jer straUfic,'l-::ic::J.:.d

well pronounced} essentially complete fall circulation considering its

narro..... shape end great average depth. In winter, a pronounced density

length. At maximut:1 development in late winter it reaches to Last C:1~~n(;e or

curre:1t from the Colorado River extends through about 75% of the reservoir's

Rock Creek. It sinks at a nearly uni:'Ort'l slope from ''''here it ente:'s the

reservoir to a depth of approximately 140 feet at th.e Escalante Ri Vcr.

Frcn this point do.m reservoir it drops rather sharply toward the bottom

and is lest near Last Chance (Figure 14).

In 1953 and 19'~4 a ter:rperature and chemical abnormality has also been

present during the fall and '....inter seasons. This tcJ-::es the form of Cl mass

of water located beti{een Warm Creek and Rock Crcek at about 100 to 200 feet

in depth (Figure 14). Characteristically} it is t._;o to six degrees war::1cr

than the surrounding water layers} Cl?proxirnately 3.0 pprn lover in ,l:.ssol'.'ed

Total hardness of this ~ater is increased by nearly 100 ppm. Che:nical

oxygen concentrations, and has about 20 ppm higher alkalinity readi:-.[:s.

measurement s thi s year, ho',.;ever} have not shmoiD the r::arginal spo:-t fish

habitat as was the case in 1963 when oxygen was dep:-essed to less than 1.5

ppm.

It is hypothesized that this cor:di tion is c8.uscd by the .:aters of t:1e

COlor,::do River runninG under tile thcl':~,ocline durin/,; til'~ ~Unllncr 1l:'_'I;Lhs to

this point in the reservoir.

There the high crga:1ic load of t~e

yo.": -r.:-..........
.... ..J... '_.l.

of this n:aterial produces an oxyger. d'2ficie:1cy.

concentrates as the current is lost and during the late fall the deco:~,]csitiol~

There is evidence of an oxygen sag in and belo" the ther~oclir.e d~rinG