,
Regulation
A
PLUS
~T
SENATOR WASH DAM
)
by T. H. MOSER, Project Manager - _ - _ _ _ _
at Yuma, Arizona
H
ERE'S a dam which never will dam the source of its water. Yet when it starts continuous oper,.tion, it will sa\"e enough Colorado River wa·ter inn ycl\r to supply a city the size of Washing·
ton, D.C.- li0,000 acre-feet.
This is Senator Wash Dam, recently completed. With its unique, regulating-type rcserroir hlwing a usable cilpi,city of 12,250 a.ere-feet, the amount of water it, saves in 12 months will be more than 14 times that figure. That's what Regulation can do in the field of water reclamation.
Although it regulates the water in the m"in
~tern of the Colorado River, Sena.tor 1',.a.sh Dam
is actually located 011 a side wash or channel about
20 miles upri,·er from Yuma, Ariz. To accom-plish its unique purpooe--multisencice regula·
tion-w,1ter is pumped into Senator Wash
Reser-,·oir when the ri,·er contains a,1 ex= flow. Later,
it is released bark to the river when it can be fully utilized for irrig-.ltion.
This regulation will conserve irregolar flows of the river which result from unscheduled ch,.nges in irrigation di¥ersions upstream, from storm in
-flows, or from ,·agaries of the river charmel. Another need for regulation is because of irri· gation va rint ions in the areas served by Imperial Dam which is immediately downstream. Weatli·
er, or other chan~'E!S that affect the ril"er can origi-nate any place in the 145,000-acre irrigated nren in
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Arizona, or the irrigated 550,000-acre area in southern Califomia including the Imperial and Coachella. Valleys.
Rows Were Excess
Tn the past-since Imperial di version dam h..s
"!most no storage capacity-most of the unused
flows from that dam have passed down the river
to :\fexico in excess of scheduled deliveries as agreed in " 1944 tre<lty. Previously this o,·erage was lost for any use in the United States, but much of it cm1 now be sah·aged by storing it in Senator
"'ash Reservoir until needed.
The dual-purpose pumping units which push
Colorado River water into the reservoir are revers-ible and serve another oper-.i.tion, that of tuming hydroelectric generators during the release of water b,ick to the rit"er. In this wa.y, water re-turning to tho rh·er generates salable power and recovers some of the pumping costs.
Power fol· the pumping operation is obtained from the upstre,un Parker-Da.vis power generation and the power b.-enen,ted from the new dam's re·
tum flows-having a 7,200-kilowatl capacity-
?-goes back into the power system where it is llnil-ablo for a growing power market.
Aeriol vi•w of Senator Wash Dam and Re.seNoi, lcenterl. Sq .... aw lole Di•• and the duol·pwpon Pump..Generoting Plant o,.. at
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How I\. Operates
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TI,• power equipment at Senat.or Wash ties into tho T ,.,.er-Davis system by an JS-mile, 69 kilo· ,·olt transmission line. But when pumping, the
six new 48-inch turbines will be able to pump more than 900 cubic feet per second against a full reser-.-oir head
""cl
will release more than t,000 cubicfeet per second. Xormnlly, however, not o\"er five units are operated at one time, with the sixth serv-ing as a spare.
T
his
extra unit allows for 'main -tenance lo be performed without having to curtnil
service-This two-purpose plant is operated by remote control from
J
mperial Dam where the Bureaua.I-ready has an operator on duty around the clock. With irrigation in this ..uizona-Cnlifornia area carried on for 12 months a year and with year-round deliveries to )lexico, operMions at Imperial and $en,\tor Wash Dams will be continuous.
Im·estigntions for a pump-storage and water
salvage project in the lower Colorado River a.rea
were initiated in 1962 and its feasibility soon
be-came apparent.
Named After Mine
The name "Senator Wash" is derived from the abandoned "Senator Gold Mine," located near the wash. Built as a feature of the Bmeau's Colorado Enjoyable octivitie• on Labor Day 1966 o:t Senator Wash Reservoir.
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FEBRUARY 1967 15
River Front Work and Levee System, the Sen,1tor Wash facilities include ,i 2,340-foot-long earthfill
dam across the main wash and a concrete overflow spillway. The prime contractor was l\f. M. Sundt Construotion Co. of Tucson, Ariz.
To impound water in the reservoir, low swales are blocked by two dikes, the largest of which is
Squaw Lake Dike. Constructed into this struc· lure is" 10-foot-diameter outlet. pipe which carries water to and from the river by way of the pump-generator plant.
During construction considerable local interest was displayed because the dam would transform a desofate, normally dry wash into a sizable clear bluo body of water.
Even though the adjacent Colorado River al-ways has flowing water, boating is treacherous
be-CU.llSe of sandbars, snags, and meanders.
How-e,·er, the 300 to 470 acres co,,ered by the fetching Senator Wash Reservoir would cause large areas
of open water.
Before construction was completed in 1966, the reservoir began its rolo of salvaging water. Heavy
rains in the watershed during November ,ind
De-cember 1965, produced enough runoff to start impoundment.
During Janu&ry 1966, the contractor st.<trted pumping water into the reservoir lo test the inst,,]. lation of the pumping-generating equipment. In August the resen-oir was completely filled for the first. time. Howe,-er, normal operation of the plant has been temporarily interrupted, because it
be-came necoosary to correct a manufacturing defect
that showed up in the turbines afler their initial
succcssrul lestinJ?. Proved Itself
Even though it bas operated only " short time, tho ,tructnre bepn proving it$elf. As n. means of conservinp: water. for e,,.mple--<luring the first.
5 months of operation from April through At1!,'USf
1966-the
csooss
deliveries to Mexico were only 4,000 acre-feet as compared with the typical 02,000 acre-fe<.-t for the same mouths of 1961 and 76,000acre-foot for 1962. ~\. large part of the recent re,-duction of lhe over deli,eries is because of the new
facility.
In addition the reservoir has alre:,dy become popular for all types of water-oriented sports, as we11
as
campinj!'.. picnicking, and sightseeing. Thepaved access road built as a p1,rt of the project, has opened up n. section of the river that was previ·
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ously only accessible by bcx,t, thus incrNStRg th1> recreation potential too.
To provide for bootinii: s,Lfety and n4 ility to the reservoir, a concrete boat ramp to n.llow future launchings at any water level was con-structed beforo the water got too high. Besides speedboating and , .. ater skiing, sailboating is be-coming more and more popular on the reservoir, largely been.use of the water's depth 1uid stillness. Swimming, both in Senntor Wnsh Reserroir and the adjacent Squa.w Lake ttMn of Imperial Reser·
voir, has·become most popular on the basis of total amount of participation. To provide gre,iter swimming safety, the best adapted areas in each of the reservoirs ha.ve been designated exclusively for swimming and have been enclosed by buoy lines. Funds have not been ,illocated for the con· st ruction of beaches, however, the natural beaches at each location have proved ndequate for present use.
Has Fish Anyway
Fishing wns not considered to be ,·ery
pro.cti-cable in ,the pla nninj!'. of the proje<:t. because large fluctuating water le,·els are necessary in the oper· ation. In spit.e of the fnct that the waters have not been stocked, fishing for bass and other pme fish has become quite popufar.
Surprisingly, fish from the river ba,-e passed through the turbine pumps with no apparent harm and »ro beooming established in the reservoir. Each form of recreation has potential for in-creasing. Du ring some weekends !Mt !'ummer, the daily use exceeded 3,000 persons and this was be·
fore construct.ion of the recreational facilities. Such accommod,itions are designated for nMr future development by n. local agency.
Reclnm1,tion has only limited authority and funds to construct recreatiomil facilities; Tho Feden,1 agency will. however, supply drinking water, as well as O{her basic facilities for the health and safety of the public.
Beautification has not been overlooked. Land-scaping, indigenous to the Southwest, ha.<; been suppliecl where needed to enhance the natural beauty of the area. Care has been e.~ercised in
color-blending painted suriaccs.
In ndditiou to indirect benefits, Senator Wnsh Dnm and Regulating Reser,,oir pro"e to.be per-forming their function. They are excellent ex-amples of w,i.ter r0{1sen·ation by regulQJion. with important bonus benefits on the side. # # #
