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Annual Report Operation of the River Basin 1979 Projected Operations 1980 Basin

Wyoming

Nevada

New Mexico

o 50 100 150 Scale of Miles Contents U.S. Department of the Interior Cecil D. Andrus, Secretary

Water and Power Resources Service (Formerly the Bureau of Reclamation) R. Keith Higginson, Commissioner

January 1980 (Prepared pursuant to the Colorado River Basin Project Act of 1968, Public Law 90-537)

Morrow Point Dam, Colo. Avocet Introduction 2 Authority for Report ...... 2 Actual Operations Under Criteria • Water Year 1979 ...... 2 Projected Plan of Operation Under Criteria· Water Year 1980 ...... 3 Determination of "602(a) Storage" ...... 3 Mexican Treaty Obligations...... 3 Regulatory Wastes ~ ...... 4 Additional Releases ...... 4 Projected Plan of Operation· Water Year 1980 ...... 5 Upper Basin Reservoirs ...... 6 ...... 6 ...... 8 Curecanti Unit - Blue Mesa, Morrow Point and Crystal Reservoirs 10 Navajo Reservoir 12 14 Lower Basin Reservoirs 16 18 _ 20 River Regulation 22 Flood Control ...... 23 Beneficial Consumptive Uses ...... 24 Upper Basin Uses and Losses 24 Lower Basin Uses and Losses ;, 24 Water Quality Operations 26 Enhancement of Fish and Wildlife ...... 27 Upper Basin 27 Flaming Gorge Penstock Intake Modification 27 Lower Basin 28 Preservation of Environment ...... 29 Power Operations ...... 30 Upper Basin-Colorado River Storage Project 30 Generating Unit Maintenance 31 Lower Basin 32

1 Introduction Authority for Report Actual Operations under Criteria-Water Year 1979

Lake Powell, Ariz. The operation of the Colorado River Basin Pursuant to the Colorado River Basin Water supply in the Colorado River Basin during the past year and the projected Project Act (Public Law 90-537) of 1968, I during 1979 was about 124 percent of operations for the current year reflect am pleased to present to the Congress, average, rang ing from 70 percent for the domestic use, irrigation, hydroelectric and to the Governors of the Colorado Green River at to 177 power generation, water quality control, River Basin States, the ninth annual percent for the San Juan River at Navajo fish and wildlife propagation, recreation, report on the Operation of the Colorado Dam. flood control, and Colorado River Com­ River Basin. This report describes the pact requirements. actual operation of the reservoi rs in the Since the active content of Lake Powell Colorado River drainage area constructed was less than the active content of Lake Storage and release of water from the under the authority of the Colorado River Mead, 8,222,000 acre-feet were released Upper Basin reservoirs recognize all appli­ Storage Project Act, the Boulder Canyon from Lake Powell. Releases from the cable laws and relevant factors governing Project Act, and the Boulder Canyon Proj­ other reservoirs through September 1979 the Colorado River, including the im­ ect Adjustment Act during water year were made accordingly to meet the power poundment and release of water in the 1979 and the projected operation of these productions and other multiple-purpose Upper Basin required by section 602(a) of reservoi rs duri ng water year 1980 under requirements of the system. At the begin­ Public Law 90-537. The operation of the the "Criteria for Coordinated Long-Range ning of January and each month there­ Lower Basin reservoirs reflects Mexican Operation of Colorado River Reservoirs," after through June, the forecast was Treaty obligations and Lower Basin con­ published in the Federal Register June revised based on precipitation and snow tractual commitments. 10, 1970. data collected through the month, and the scheduled operation was revised Nothing in this report is intended to inter­ Cecil D. Andrus, Secretary accordingly. pret the provisions of the Colorado River U.S. Department of the Interior Compact (45 Stat. 1057), the Upper Colo­ The major storage reservoirs in the Colo­ rado River Basin Compact (63 Stat. 31), rado River Basin stayed within the normal the Water Treaty of 1944 with the United operating range during water year 1979. Mexican States (Treaty Series 994, 59 Aggregate storage at the end of water Stat. 1219), the decree entered by the year 1979 was 50,939,000 acre-feet which Supreme Court of the United States in represented an increase of 6,076,000 acre­ v. , et al. (376 U.S. 340), feet from water year 1978. the Boulder Canyon Project Act (45 Stat. 1057), the Boulder Canyon Project Adjust­ A description of the operations of each of ment Act (54 Stat. 774; 43 U.S.C. 618a), the reservoirs in the Colorado River Basin the Colorado River Storage Project Act follows. Charts 1-8 show the monthly out­ (70 Stat. 105; 43 U.S.C. 620), or the Colo­ flow from the reservoi rs, water su rface rado River Basin Project Act (82 Stat. 885; elevations, and active storage in the 43 U.S.C. 1501). reservoi rs for water year 1979. Projected Plan of Operation under Criteria · Water Year 1980

.-):.... Las Vegas Bay, Lake Mead, Nev. Fishing near Blue Mesa Dam, Colo. Determination of "602(a) Storage" necessity to assure that Upper Basin con­ schedule by not more than 20 percent. Section 602(a)(3) of the Colorado River sumptive uses are not impaired because During water year 1979, Mexico received Basin Project Act of September 30, 1968, of failure to store sufficient water to a total delivery of 2,766,278 acre-feet at (Public Law 90-537), provides for the stor­ assure deliveries under section 602(a)(1) the Northern International Boundary. This age of Colorado River water not required and (2) of Public Law 90-537. larger-than-usual amount was due to the to be released under article III(c) and III(d) additional 688,500 acre-foot release from of the in Upper Taking into consideration these relevant the Lower Basin reservoirs and to flood Basin reservoirs to the extent the factors, the Secretary has determined control releases from Painted Rock Dam Secretary finds it necessary to assure that the active storage in Upper Basi n on the . Compact deliveries without impairment of reservoirs forecast for September 30, annual consumptive uses in the Upper 1980, exceeds the "602(a) Storage" re­ The United States will make scheduled Basin. Article II of the "Criteria for Coor­ quirement under any reasonable range of deliveries of 1,700,000 acre-feet of Col­ dinated Long-Range Operation of Colo­ assumptions which might be realistically orado River water to the Republic of Mex­ rado River Reservoi rs" provides that the applied to those items which he is ico in water year 1980. This includes an annual plan of operation shall include a directed to consider in establishing this additional 200,000 acre-feet of water determination by the Secretary of the storage requirement. Therefore, the ac­ surplus to United States uses, pursuant quantity of water considered necessary to cumulation of "602(a) Storage" is not the to the Mexican Water Treaty of 1944. be in Upper Basin storage as of criterion governing the release of water September 30 of the current year. This during the current year. The additional water release is based determination shall consider all ap­ in part on average runoff conditions as­ plicable laws and relevant factors in­ Mexican Treaty Obligations sumed for the Colorado River Basin dur­ cluding, but not limited to: (a) historic Annual calendar year schedules of ing water year 1980. Should runoff during streamflows; (b) the most critical period monthly deliveries of water in the that time be above average, substantially of record; (c) probabilities of water sup­ limitrophe section of the Colorado River, larger releases for flood control purposes ply; (d) estimated future depletions in the allotted in accordance with the Mexican could be required from . Upper Basin, including the effects of Water Treaty signed in 1944, are formu­ Representatives of the Republic of Mex­ recurrence of critical periods of water lated by the Mexican Section and ico will be kept informed of operating supply; (e) the "Report of the Committee presented to the United States Section, schedules through the United States Sec­ on Probabilities and Test Studies to the International Boun,dary and Water Com­ tion of the Commission. Task Force on Operating Criteria for the mission, before the beginning of each Colorado River," dated October 30, 1969, calendar year. and such additional studies as the Secretary deems necessary; (f) the Upon 30 days' advance notice to the United States Section, Mexico has the right to modify, within the total schedule, any monthly quantity prescribed by the 3 Additional Releases

Imperial Dam, Ariz.-Calif. Hoover Dam, penstock flushing, Nev.-Ariz. Regulatory Wastes Water Year 1979 The Secretarial decision to release addi­ Deliveries to Mexico consist of river At the integration meeting in Boulder tional water from Lake Mead during 1979 water delivered to and City, Nev., on June 14, 1978, the Repre­ stipulated that the extra releases be waste and drainage return flows from sentative of the Secretary of the Interior accounted for as if still stored in Lake water users below Imperial Dam. In addi­ declared that Lower Colorado River Mead. Therefore, a water accounting tion to assuring normal water deliveries releases would be made to meet only procedure was developed to reflect the the small amount of regulatory stora,.ge minimum downstream water require­ reservoir storage level that would have space in Imperial, Laguna, and Senator ments for the operating year ending existed without the additional releases. Wash Reservoirs was used at times to May 31, 1979. Operation of Lower Colo­ On September 30, 1979, the actual eleva­ limit potential downstream flood rado River dams was consistent with this tion of Lake Mead was 1195.30 feet damages during water year 1979. policy through April 1979. During the (22,242,000 acre-feet). Had the additional winter months, however, precipitation in 688,500 acre-feet not been released, Lake A regulatory waste of 30,000 acre-feet has the Upper Basin resulted in much higher Mead's September 30, 1979, elevation been projected as being lost from the than average runoff flowing into Lake would have been, allowing for additional lower Colorado River for water year 1980 Powell. Furthermore, high runoff condi­ losses to evaporation and bank storage, pursuant to Minute 242. tions in the Bill Williams River and Gila approximately 1199.78 feet (22,884,000 River drainages mandated winter and acre-feet). spring flood control releases by the Corps of Engineers from Alamo and Painted Rock Dams and this indirectly re­ quired more water to be stored behind Hoover Dam. On April 27, 1979, the Secretary of the Interior approved the scheduled release of about 700,000 acre­ feet of excess water from Hoover Dam to reduce the probability and magnitude of mandatory flood releases in 1979 or 1980.

4 Projected Plan of Operation­ Water Year 1980

Lake Mead, Nev. Hance Rapid, , Ariz. Water Year 1980 releases during water year 1979. The pro­ For average runoff conditions during On August 21, 1979, the Colorado River jected water year 1980 operation study of water year 1980, the projected operation Basin States and other interested parties the system indicates that if the additional of each of the reservoirs in the Colorado met in Salt Lake City, , to consult 700,000 acre-foot releases were not made, River Basin is described in the following regarding the best operational plan for flood control releases would be required pages. Charts 1 through 8 show the releases from Lake Mead during water from Lake Mead during water year 1980. projected monthly outflow from the res­ year 1980. Due to the high probability of ervoirs and the projected end-of-month flood control releases being required On September 30, 1979, storage in Lake elevation and active storage in the res­ during 1980 or 1981, there was general Powell was only 606,000 acre-feet less ervoirs for average and three other concurrence to continue with the plan to than the storage in Lake Mead. Projected assumptions of 1980 modified runoff release about 700,000 acre-feet of water operation with normal inflow and mini­ from the Basin. The four assumptions from Lake Mead in excess of downstream mum release from Lake Powell would are: (1) Average based on the 1906-78 requirements. This operating plan is con­ cause an imbalance of storage in favor of record of runoff; (2) Upper Quartile based sistent with the declaration made by the Lake Powell. Therefore, the plan of opera­ on the level of annual streamflow which representative of the Secretary of the In­ tion must incorporate the equalization of has been exceeded 25 percent of the terior at the integration meeting held storage concept. Since releases from time during 1906-78; (3) Lower Quartile June 13, 1979, in Boulder City, Nev. to Hoover in addition to downstream re:­ based on flows exceeded 75 percent of release water from Hoover Dam sufficient quirements were made during water year the time during 1906-78; and (4) Most to generate contract defined firm energy 1979 and a similar plan is made for water Adverse based on the lowest year of during operating year 1980. In connection year 1980, the Secretary determined for record, which was 1977. with the "Filling Criteria" and equaliza­ "Operating Criteria" purposes that Lake tion of storage, these releases will be Powell shall be operated as if those addi­ The projected operations of Lake Mead, accounted as stored in Lake Mead, con­ tional releases were to remain in Lake Lake Mohave, and Lake Havasu are the sistent with the treatment of the excess Mead. Consequently, the same under all of the runoff assumptions, release will be determined by equalizing except for Lake Mead flood control storage in Lake Powell and Lake Mead as releases under Upper Quartile conditions. if the additional water released had re­ mained in Lake Mead.

5 Upper Basin Reservoirs Fontenelle Reservoir (Green River)

Water Year 1979 Water Year 1980 Fontenelle Active Storage* Chart 1 Fontenelle Reservoir is operated for At the beginning of water year 1980 the power generation, water supply, flood elevation of Fontenelle Reservoir was Reservoir (Acre-Feet) EI.(Ft.) control, fish and wildlife enhancement 6499 with a content of 290,000 acre-feet. Maximum Storage 344,834 6506 and recreation. During the fall and winter The release, having been 800 ft3/s, will be Rated Head 233,789 6491 of 1978-79 the water surface was grad­ adjusted, depending upon inflow, to draw Minimum Power 194,962 6485 ually reduced from elevation 6503 feet down the reservoir to elevation 6478. This Surface Area (Full) 8058 Acres at the beginning of the water year to a elevation is 7 feet lower than the usual Reservoir Length low elevation of 6485 in April prior to draw-down which is made to facilitate (Full) 18 Miles the spring runoff. The minimum release maintenance in the spring. Power Plant during the fall and winter was 600 cubic The reservoir will fill in June 1980 unless feet per second (ft3/s). The maximum in­ the inflow is less than average. After the Number of Units 1 flow of 8,000 ft3/s occurred on the 30th spring runoff, the reservoir level will be Total Capacity 10,000 Kilowatts of May. The maximum release was 4,750 controlled by adjusting the releases *does not include 563 acre-feet of dead storage ft3/s. The mclximum elevation of 6501 feet through the powerplant to reduce slowly below 6408 feet was five feet below capacity. The the elevation to 6504 feet by the end of minimum possible power generating the summer of 1980. release through the powerplant is 500 ft3/s. The maximum release through the The maximum release will depend mostly powerplant is 1750 ft3/s at rated head. on the magnitude of the inflow but also on the forecast error. The maximum re­ lease will probably be less than 15,000 ft3/s unless the inflow is larger than has historically been experienced. If the in­ flow is in the upper quartile amount, the peak outflow will probably be less than 10,000 ft3/s. If the inflow is average, the peak outflow will probably be less than 7,000 ft3/s. If the inflow is at about the lower quartile, the peak outflow will prob­ ably be less than 3,000 ft3/s.

6 Fontenelle Powerplant, Wyo. Fontenelle Dam and Reservoir, Wyo.

Outflow Release in 1000 Cubic Feet/Second Storage Actual Operation 1979 Usable Content in 1000 Acre-Feet Elevation (Feet) Non-linear Scale 4 3...---+----+----I--+--+-~--+--+---+---t---+-----t

2 3451---+--+---+_1--+--+--+---+-t--+--+---+---+-+---+--+---+----t-+---t--+---; 6506 1 Projected Operation 1980 300 6500 Upper Quartile 7 6 5 200 4 3 2 .t--_+_---t--_t___+___t_- 1 100 Average 5 4 o 0 N 0 J FMAM JJ A SON 0 J FMAM J IJ IIAI..I"'sl._... 6392 3 Actual 1979 Projected 1980 21 iii

Lower Quartile Legend 3 Most Probable 2...---+----+----I--+--+---+-+----i. Upper Quartile 1 Lower Quartile Most Adverse •••••••••• Most Adverse 3 2...---+----+----I--+--+-~--+--+---t---t---+-----t 1 o N 0 J FMAM JJ AS 7 Flaming Gorge Reservoir (Green River)

Flaming Gorge Dam, Utah-Wyo. Canadian Geese

Water Year 1979 Water Year 1980 Flaming Gorge Active Storage* Chart 2 At the beginning of water year 1979, the At the beginning of water year 1980, the Reservoir (Acre-Feet) EI. reservoir water surface was at elevation active storage at Flaming Gorge was (Ft.) 6015 feet with a content of 2,825,000 2,571,000 acre-feet with the water surface acre-feet. The April through July 1979 elevation at 6008 feet. The reservoir Maximum Storage 3,749,000 6040 runoff above Flaming Gorge was 777,000 level will be drawn down to about 5999 feet before the spring of 1980 and shouId Rated Head 1,062,000 5946 acre-feet which is 68 percent of the long­ 233,000 5871 time average. With this runoff, the reser­ remain high enough so boats can be Minimum Power 42,020 Acres voir reached its seasonal maximum eleva­ launched from the nine boat ramps. Surface Area (Full) Reservoir Length. tion of 6015 feet the last of June 1979 Average inflow would cause the reservoir (Full) 91 Miles with a content of 2,715,000 acre-feet. By to reach elevation 6015 feet with an ac­ the end of September, the elevation was tive storage of 2,800,000 acre-feet during Power Plant 6008 feet with a content of 2,571,000 July. Under average conditions, summer­ Number of Units 3 acre-feet. time flow in the river below the dam is Total Capacity 108,000 Kilowatts 3 not expected to exceed 4600 ft /s, or fall *does not include 40,000 acre-feet of dead storage The normal minimum release is 800 ft3/s. below 800 ft3/s. below 5740 feet The maximum release through the power­ plant is 4600 ft3/s at rated head. Since there is enough space to store a high inflow and enough water in storage in case of low inflow, the release from Flami·ng Gorge Reservoir is not depen­ dent upon the inflow for water year 1980.

The release is dependent upon the de­ mand for electric power and the availabil­ ity of energy for purchase and exchange. In projecting the 1980 operation, it has been assumed, based on past experience, that if the inflow is high there would be more low-cost energy available to pur­ chase; therefore, the release would be less. Also, if the inflow is low, there would be less energy available and the release would be increased to produce the required energy. 8 Flaming Gorge Selective Withdrawal Structures, Utah-Wyo. Outflow Release in 1000 Cubic Feet/Second Storage Actual 1979 Usable Content in 1000 Acre-Feet Elevation in Feet (Non-Linear Scale)

1-_-+--4--+---+-I---+__-+---+--+-__+~I__+___+__I__-+-__+-----f-+---+---+--+---+-+-----l6040 3 2 1 I---+-----I-_+_--+-~I__+___+__I___+_--+------f-+__+__t__+___+___+-+__+__I__~IL__t_-+____j6021 Projected Operation 1980 Upper Quartile 6000

3 2 1

Average

2 1

Lower Quartile

3 Legend 2 1 Most Probable Upper Quartile Lower Quartile Most Adverse Most Adverse

3 2 1 o NDJFMAMJJAS 9 Curecanti Unit () Morrow Point Reservoir Crystal Reservoir

Blue Mesa Dam and Powerplant, Colo. Blue Mesa Reservoir - Colorado 149 Bridge, Colo.

Water Year 1979 Water Year 1980 Blue Mesa Active Storage* Chart 3 The Curecanti Unit includes Blue Mesa, During the current year, water level in Reservoir (Acre-Feet) EI.(Ft.) Morrow Point, and Crystal Reservoirs. Blue Mesa should reach a low elevation Blue Mesa provides nearly all of the long­ of 7468 feet in April 1980; at that eleva­ Maximum Storage 829,523 7519 term regulation for all three powerplants. tion the active storage would be about Rated Head 249,395 7438 Morrow Point provides peaking power 424,000 acre-feet. With average inflow Minimum Power 81,070 7393 and thus has highly variable releases. The during the spring of 1980, the reservoir Surface Area (Full) 9,180 Acres primary function of Crystal Reservoir is to should reach elevation 7514 with an ac­ Reservoir Length re-regulate the variable Morrow Point tive storage of 780,000 acre-feet. At that (Full) 24 Miles releases. elevation the reservoir has a surface area Power Plant of 8,884 acres. Number of Units 2 At the end of September 1978, Blue Mesa Total Capacity 60,000 Kilowatts g~roswn~~J~1~~e Reservoir contained 728,000 acre-feet of Morrow Point Reservoir will be operated * 111,232 acre-feet of dead storage active storage with a water surface eleva­ during the current year at or near its max­ Morrow Point Active Storage* tion of 7508 feet. The April through July imum storage capacity. Crystal Reservoir Maximum Storage 117,025 7160 1979 inflow to Blue Mesa was 935,000 will be operated nearly full except for Rated Head 79,805 7108 acre-feet, which was 119 percent of daily fluctuations as required to regulate Minimum Power 74,905 7100 the releases from Morrow Point to meet normal .. The 1979 water year total was Surface Area (Full) 817 Acres 1,146,000 acre-feet. The water surface of diversion requirements downstream from Reservoir Length the Gunnison Tunnel. Blue Mesa was raised to lNithin one-half (Full) 11 Miles foot of capacity. This was done to pre­ Power Plant vent a spill from occurring. If the inflow to Blue Mesa Reservoir is at Number of Units 2 the upper quartile, the release will prob­ 3 Total Capacity 120,000 Kilowatts The drawdown for power operations and ably average 2800 ft /s for several weeks *does not include 165 acre-feet of dead storage river regulation purposes was great in June and July 1980. The powerplant below 6808 feet enough that no further space evacuation capacity is 3000 ft3/s. For the average Crystal Active Storage* was required for flood control. lower quartile and most adverse inflows, Maximum Storage 17,573 6755 the highest monthly release is projected Rated Head 13,886 6742 During water year 1979, all flows in to be about 1400 ft3/s in July 1980. Minimum Power 10,619 6729 the Gunnison River below the Gunnison Surface Area (Full) 301 Acres Tunnel were greater than 200 ft3/s, the Reservoir Length minimum discharge required to protect (Full) 7 Miles the fishery in the river. Power Plant Number of Units Total Capacity 28,000 Kilowatts g~r~wn6Jio1~~e 10 * 8,200 acre-feet of dead storage Morrow Point Dam and Reservoir, Colo. Morrow Point Reservoir scenic cruise, Colo. Crystal Dam and Reservoir, Colo.

Outflow Blue Mesa Reservoir Storage Blue Mesa Reservoir ActlJal 1979 Release in 1000 Cubic Ft/Sec Usable Content in 1000 Acre-Feet Elevation in Feet (Non-Linear Scale)

900 .----+-_+___+__+-+---+---+---+---+-~_+___+__+___+___l-_+___+__+___+__+-+___+___t_____; 2 830 7519 800 ~7516

Projected Operation 1980 700:" " ~7505 Upper Quartile 600 "'7492 500 ": 7479 400 "7465 " 7450

7428 2 t--+---+--~ 7400

o N 0 J F M A M J J A SON 0 J F" "M"'A "M"'''"J" j";"'~A """S"W"": 7186 Actual 1979 Projected 1980 Lower Quartile

2~+--+---+-1----+--+---+----11--+--+---+---t

Legend Most Adverse Most Probable Upper Quartile

2~+--+---+-1----+---I---+----11--+--+---+---t Lower Quartile Most Adverse ••••••••••

o N0JFMAMJJAS 11 Navajo Reservoir (San Juan River)

Navajo Dam and Lake, N. Mex.-Colo. Water Year 1979 Water Year 1980 Navajo Active Storage* Chart 4 During the first part of water year 1979, a On September 30, 1979, Navajo Reservoir minimum release of 530 ft3/s was made had 1,364,000 acre-feet of storage at an Reservoir (Acre-Feet) EI. from Navajo Reservoir for consumptive elevation of 6062. Assuming average in­ (Ft.) use and maintenance of fish and wildlife. flow, the elevation is projected to be 6037, with a content of 1,080,000 acre­ Maximum Storage 1,696,400 6085 Because a record amount of snow fell feet, before the snowmelt runoff starts. Inactive Storage 660,500 5990 during 1979 in the San Juan Basin, water Average inflow would cause the reservoir Surface Area (Full) 15,610 Acres releases were gradually increased to ap­ to reach elevation 6063 feet with a con­ Reservoir Length proximately 5000 ft3/s. This rate of release tent of 1,384,000 acre-feet in July 1980. (Full) 33 Miles was maintained for several months in This approximate elevation would be *does not include 12,600 acre-feet of dead storage order to maintain storage space to con­ maintained the remainder of the summer below 5775 feet tain the expected high runoff. to enhance recreational use.

Operations for flood control decreased The release from Navajo Reservoir for an the flow at from more than upper quartile inflow is projected to be 12,000 ft3/s to 5280 ft3/s, thus reducing about 1700 ft3/s for the winter, spring, flood damage. Since there was no need and summer of 1980. The release for an to fill Navajo Reservoir and to provide ex­ average inflow is expected to be 1700 tra flood control space in case inflow was ft3/s for the winter and spring, then greater than expected, the reservoir was decrease to 800 ft3/s for the summer. The not completely filled. The maximum con­ release for the lower quartiIe is projected tent was 1,559,000 acre-feet, which is to be about 1500 ft3/s for the winter, 1200 137,000 acre-feet less than maximum ft3/s for the spring, and 700 ft3/s for the capacity. summer. The release for a most adverse inflow is projected to be about 1200 ft3/s The April-July inflow was 1,570,000 acre­ for the winter, and 530 ft3/s for the spring feet, which is 217 percent of the long­ and summer of 1980. time average.

12 Navajo Dam Spillway, 1973. Navajo Dam and Lake, N. Mex.-Colo.

Outflow Release in 1000 Cubic Feet/Second Storage Actual Operation 1979 Usable Content in 1000 Acre-Feet Elevation in Feet (Non-Linear Scale) 5 CIITICI=dII._ 4 I---+--!-~--I---+--,,;mrnmwm;vw;;; 3 21---+---+----+----+- 1696 +---+---+---+---+----+_1-----+---+--+--+---+----+-+--+---+---+---+---+~-~__l6085 1 ,,,,,,.,,, "., ". ,.." , ,.,.,.,,, ""~,~~I,,,,~I,~I, .I."~ 6072 Projected Operation 1980 Upper Quartile IIIIIII 4 III I I 31 IIII III 6029 2 I 1

Average 500

4 3.....-..-+---+-----4-+-----i---+-----4-+---i---+---+----f

2 ONDJ FMAMJJ ASONDJ F 1 Water Year 1979 (Actual) Projected 1980

Lower Quartile Legend Most Probable 3 Upper Quartile 2 " Lower Quartile 1 iii. Most Adverse •• •••••••... Most Adverse

3 21----+--+----+-+---+--+----+-i---+--+---t--t 1 o N 0 JFMAMJJAS 13 Lake Powell (Colorado River)

.~ and Lake Powell, Utah-Ariz. Glen Canyon generators.

Water Year 1979 Water Year 1980 Lake Powell Active Storage* Chart 5 During water year 1979, Lake Powell, The elevation of Lake Powell at the end Reservoir (Acre-Feet) EI. impounded by Glen Canyon Dam, was of September was It is ex­ 1979 3678. (Ft.) operated as part of the Colorado River pected to be drawn down to elevation Storage Project in accordance with gover­ by the spring .of Assuming an 3670 1980. Maximum Storage 25,002,000 3700 ning contracts and laws to provide river average April-July inflow of about 8 mil­ Rated Head regulation, optimum power production, 9,428,000 3570 lion acre-feet, the elevation would reach Minimum Power 4,126,000 3490 recreation opportunities, and fish and 3694 in July 1980 with a content of about Surface Area (Full) 161,390 Acres wildlife benefits. 24 million acre-feet which is 96 percent of Reservoir Length active capacity. The surface area would (Full) 186 Miles On September 30, 1978, Lake Powell be 157,000 acres with a length of 185 Power Plant water surface elevation was at 3640 feet miles. Assuming average conditions, with an active storage of 16,563,000 acre­ 8,330,000 acre-feet are scheduled for Number of Units 8 feet. During the fall and winter months of release from Lake Powell in water year Total Capacity 900,000 Kilowatts the reservoir water level dropped 1978-79, 1980. This release will split the storage *does not include 1,998,000 acre-feet of dead about 12 feet to elevation 3628 feet. Low with Lake Mead after accounting for addi­ storage below 3370 feet releases from Glen Canyon during March tional releases made from Lake Mead and April allowed the Water and Power during 1979 and 1980 in anticipation of Resources Service to integrate purchased flood control operations. This is more power into the Colorado River Storage than the minimum release of 8,230,000 Project system when it was readily acre-feet identified as an objective in available. The April-July 1979 runoff of by the operating criteria. the Colorado River at , Ariz., was 10,045,000 acre-feet, or 139 percent If the inflow to Lake Powell is at the of the long-time average. This inflow lower quartile or less, the release will be raised the level of Lake Powell to an all­ 8,230,000 acre-feet. If the inflow is time high of 3685 feet in July of 1979. average, the release is projected to be 8,330,000 acre-feet. If the inflow is at the upper quartile, the release will be 9,742,000 acre-feet as required by the filling criteria to split storage with Lake Mead, after accounting for the additional releases from Hoover Dam as if still stored in Lake Mead. Most of the differ­ ence in release would be in the summer of 1980.

14 Electricity for home use Glen Canyon Dam, Utah-Ariz. Inflow - Outflow Storage Actual 1979 in 1000 Cubic Feet/Second Content in Million Acre-Feet Elevation in Feet (Non-Linear Scale) 50 f--+--f--+-I---I---I--+-hi'-~-I----&-----4 3700 40 f--+--f--+-I---I---I--+-+-I---I----'~___&_____4 25 CCDD=1=I=t=t=t=IIIIIrrrr=CI2t:iiilii 30 f---+---f--+-f---I---I-~L--I---I--~__+~ 20 I--+---+-­ 10 20 f----I--+---+-+--+---+--+---l-_f_, Projected 1980 Upper Quartile 50 ,..---,---.,.----r-r---r---y----,...-r---r---y------r_ 40 f---+---I---+--I---I---+---I~lq--~--+-+----1 15 30 f---+---f--+-f--+--I---h~f--+4r--+-__+~ 20 f---+--+-="""*-+---+----+-",...e-+-+---+--,; 10

10 Average

40 f---+---I---+-+--+--+---If----I-=::-+---+-+---1 30 f---+--+---+-+--+--+---If--.-2III~--PiII:~'+-+--1 3506 20 1---+---+---+--I---4-----f-,~I---_+_-+-~..._+---J 5 10

>XY».'> >:=::~::~=:.,»>., ·3132 Lower Quartile J ASONDJ F 30 f---+--+---+-+--+--+---+---Jq.---Pilr--+---+----I Projected 1980 20 ....---+--+---+-+--1---+-~-4--+-~-+--_t 10 Iii..

Most Adverse Legend 20 1---I---I--+-+---+---I---+-+---f--~__+-1 Most Probable Upper Quartile 10 ... Lower Quartile o NDJFMAMJJAS Most Adverse -- ••••••• .. •

15 Lower Basin Reservoirs Lake Mead (Colorado River)

Hoover Dam and Lake Mead, Ariz.-Nev.

Water Year 1979 Water Year 1980 lake Mead Active Storage* Chart 6 At the beginning of water year 1979, Lake During the 1980 water year, the Lake Mead, impounded by Hoover Dam, had a Mead water level is scheduled to rise to Reservoi r (Acre-Feet) EI. (Ft.) water surface elevation of 1185 feet and elevation 1203 feet at the end of February an active storage of 20,890,000 acre-feet. 1980, then be drawn down to a low eleva­ Maximum Storage 27,377,000 1229 During the water year, releases were tion of 1192 feet at the end of June 1980. Rated Head 13,653,000 1123 made to meet downstream water use re­ At that level the lake will have an average Minimum Power 10,024,000 1083 quirements in the United States and Mex­ active storage of about 21.8 million acre­ Surface Area (Full) 162,700 Acres ico, programmed levels of Lake Mohave feet. During water year 1980, a total of Reservoir Length and Havasu, and transit losses which 8.2 million acre-feet is scheduled to be (Full) 115 Miles include river and reservoir evaporation, released from Lake Mead to meet all Power Plant uses by phreatophytes, changes in bank downstream requirements; this includes storage, unmeasured inflows, and diver­ about 700,000 acre-feet additional Number of Units 17 sions. Additional anticipatory releases scheduled release. All releases are Total Capacity 1,344,800 Kilowatts totaling 688,500 acre-feet were made from scheduled to pass through the turbines *does not include 2,378,000 acre-feet of dead Hoover Dam and downstream reservoirs for electric power production. storage below 895 feet during water year 1979 to decrease the likelihood of having to make flood control With an upper quartile inflow to the releases during 1980 and 1981. The total system's reservoirs, it is anticipated that release from Lake Mead through Hoover instantaneous peak discharges from Dam was 7,388,000 acre-feet. At the end Hoover, Davis, and Parker Dams would of the water year, Lake Mead had a water not be greater than normal year peaks; surface elevation of 1195 feet and an ac­ however, sustained discharges may pose tive storage of 22,242,000 acre-feet, minor problems in the United States por­ which, in spite of additional releases, tion of the Lower Basin and more signifi­ reflects an increase in storage during the cant problems within the Republic of water year of 1,352,000 acre-feet. Mexico.

On September 30, 1979, the active storage of Lake Mead was 606,000 acre­ feet more than the active storage in Lake Powell.

16 Lake Mead Marina 19 Millionth Visitor - Hoover Dam Outflow Release in 1000 Cubic Feet/Second Storage Actual 1979 Active Content in Million Acre-Feet Elevation in Feet (Non-Linear Scale) 27.4'J---+~~--I--+--+---+--+--+---+--+--+--t-t---+--+--+--t--t---t---r--t-r----;I 1229

25 f----+---+-----i 1214

Projected Operation 1980 Upper Quartile

Average, Lower Quartile, Most Adverse

15 10 ~-+---+---+- 5 o N 0 JFMAMJJAS 5

895 ONDJFMAMJJASONDJ FMAMJJ Actual 1979 Projected 1980

Legend Most Probable Upper Quartile

17 Lake Mohave (Colorado River)

Davis Dam and Lake Mohave, Nev.-Ariz. spillway Water Year 1979 Water Year 1980 Lake Mohave Active Storage* Chart 7 At the beginning of water year 1979, the The water level of Lake Mohave is water surface elevation of Lake Mohave, scheduled to rise through the fall and Reservoir (Acre-Feet) EI. which is impounded by Davis Dam, was winter months and reach elevation 643 (Ft.) 635 feet with an active storage of feet by the end of February 1980. It Maximum Storage 1,810,000 647.0 1,479,000 acre-feet. should remain near that yearly high eleva­ tion through May 1980. Because of heavy Rated Head 1,188,000 623.0 During the winter months, the water level irrigation use during the summer months, Minimum Power 217,500 570.0 Surface Area (Full) 28,200 Acres was raised to 645 feet, with an active the water level in Lake Mohave is ex­ Reservoir Length storage of 1,760,000 acre-feet on February pected to be drawn down to elevation 631 (Full) 67 Miles 6, 1979. The water level was drawn down feet by the end of water year 1980. During Power Plant during the summer months to its lowest that time, a total of 8.3 million acre-feet is elevation of the year, 633 feet. The reser­ scheduled to be released from Lake Number of Units 5 voir ended the water year at elevation 633 Mohave to meet all downstream require­ Total Capacity 240,000 Kilowatts feet with 1,428,000 acre-feet in active ments and the additional 700,000 acre­ *does not include 8,530 acre-feet of dead storage storage. feet release. All releases are scheduled to below 533.39 feet pass through the turbines for electric Lake Mohave releases were made to power production. satisfy downstream requirements, with a small amount of re-regulation at Lake With an upper quartile inflow to the Havasu. The 688,500 acre-feet of addi­ system's reservoirs, it is anticipated that tional releases from Hoover Dam were instantaneous peak discharges from also routed through Lake Mohave. During Hoover, Davis, and Parker Dams would not the water year, 7,646,000 acre-feet were tie greater than normal year peaks; released at Davis Dam, all of which however, sustained discharges may pose passed through the turbines for power minor problems in the United States por­ generation. tion of the Lower Basin and more signifi­ cant problems within the Republic of Mexico.

18 Citrus groves, Ariz. Palo Verde squash, Calif. Lake Mohave Outflow Lake Mohave Storage Actual Operation 1979 Usable Content in Million Acre-Feet Elevation in Feet (Non-Linear Scale)

1.8 1----I-----+-~-+--I-----+-~-+--+---+-+---+--+----+-_+____+__+____1f___+__+___+-+____t___; 15 1Ot---+---t---+-~ 5 _1i11lli. 1.5 636 Projected Operation 1980 Upper Quartile

1.0 15 10 5

Average, Lower Quartile, 589 Most Adverse

15 10t---+--+---+-- 5 o N 0 J FMAM JJ AS

~19 Lake Havasu (Colorado River)

Parker Dam and Powerplant, Ariz. Colorado River Wat&r Year 1979 Space in the top 10 feet of Lake Havasu Lake Havasu Active Storage* Chart 8 At the beginning of water year 1979, the (about 180,000 acre-feet) is reserved by Reservoir (Acre-Feet) EI.(Ft.) water level of Lake Havasu, impounded the United States for flood control and by , was at elevation 447 feet, other uses, including river regulation. Maximum Storage 619,400 450.0 with an active storage of 565,000 acre­ Normally, only about the top 4 feet, or Rated Head 619,400 450.0 feet. The reservoir was drawn down to 77,000 acre-feet, have been used for this Minimum Power 439,400 440.0 about elevation 444 feet with an .active purpose since Alamo Reservoir on the Surface Area (Full) 20,400 Acres storage of about 509,000 acre-feet in Bill Williams River has been in operation. Reservoir Length February. This provided flood control (Full) 35 Miles space for runoff from the drainage area Water Year 1980 Power Plant between Davis and Parker Dams. The Lake Havasu is scheduled at the highest water level was then raised to about levels consistent with the requirements Number of Units 4 elevation 448 feet by mid-May. During for maintaining flood control space. The Total Capacity 120,000 Kilowatts mid-May through June, the reservoir yearly low elevation of 445 feet is *does not include 28,600 acre-feet of dead storage water level was maintained between 448 scheduled for the high-flood hazard below 400.0 feet and 447 feet, with an active storage of period of October through March. The about 562,000 acre-feet at the end of yearly high of 450 feet is scheduled for June. By the end of the water year, Lake the low-flood-hazard month of June. Havasu was at 447 feet, with an active Du ri ng water year 1980, a total of 7.3 storage of 565,000 acre-feet. million acre-feet is scheduled to be released from Lake Havasu to meet all During the water year, 6,729,000 acre-feet downstream requirements, including the were released at Parker Dam, all of which additional 700,000 acre-foot release. All passed through the turbines for power releases are scheduled to pass through generation. That amount included the ad­ the turbines for power production. ditional releases from Lake Mead which totaled 688,500 acre-feet during the year, With an upper quartile inflow into the and flood control releases of approx­ system's reservoirs, it is anticipated that imately 226,000 acre-feet from Alamo instantaneous peak discharges from Dam on the Bill Williams River. Hoover, Davis, and Parker Dams would not be greater than normal year peaks; however, sustained discharges may pose minor problems in the United States por­ tion of the Lower Basin and more signi­ ficant problems within the Republic of Mexico. 20 Hay bales Parker Dam and Lake Havasu, Ariz.

Outflow Release in 1000 Cubic Feet/Second Storage Actual Operation 1979 Usable Content in 1000 Acre-Feet Elevation in Feet (Non-Linear Scale) 450 .---+---+---+-f---+--+---+----f-+---+--+--+---f-+--_+_-+---+--I---+--+--+~~_+____l 449 15 1 01----4---+-~+---+-- 5_..ibii 444 Projected Operation 1980 Upper Quartile 438

• 431 - 424 ONDJ FMAMJJ ASONDJ FMAMJ J AS Actual 1979 Projected 1980 o ND J FMAM JJ AS

21 River Regulation

Lees Ferry on the Colorado River Lake Powell The natural virgin runoff reaching the The projected release from Lake Powell, the normal releases are made when con­ streams of the Colorado River drainage based on the most probable forecast of ditions permit satisfactory water recrea­ system above Glen Canyon Dam during runoff is 8,330,000 acre-feet. This could tional activities. Adjustments are also water year 1979 was estimated at about vary from a minimum of 8,230,000 acre­ made to transport riverborne sediment to 17.9 million acre-feet. Of this amount, feet with most adverse or lower quartile desilting facilities, and to assist in con­ about 3.5 million acre-feet of water was runoff to 9,635,000 acre-feet with upper trolling water quality. Minimum releases consumptively used within the Upper Col­ quartile runoff. When added to the flow from Lake Powell were 1,000 ft3/s during orado River Basin States. of the , this would result in the winter months and were increased to an Upper Basin delivery ranging from 3,000 ft3/s during the summer months Adjustments in storage in other main­ about 87.1 to 88.6 million acre-feet for the with an average daily flow of 8,000 ft3/s. stream reservoirs resulted in an inflow to 10-year period ending September 30, These flows in the Grand Canyon are Lake Powell of 14.6 million acre-feet. The 1980. typical of a normal water year. They are release from Glen Canyon Dam, based on similar to flows in past years and have measurements at the gaging station at Water releases scheduled for the Colo­ proven satisfactory to recreational users Lees Ferry, Ariz., was 8,222,000 acre-feet. rado River Storage Project and partici­ in the Grand Canyon. For the 1-year and 10-year periods end ing pating project reservoirs were planned September 30, 1979, 8,293,000 acre-feet to accommodate all of the multiple River regulation below Hoover Dam re­ and 87,565,000 acre-feet, respectively, purposes for which the project was sulted in delivery to Mexico of 1,266,278 passed the compact point at Lee Ferry, designed, in addition to the many acre-feet in excess of the normal treaty­ Ariz. day-to-day demands which develop guaranteed quantity of 1,500,000 acre-feet throughout the year. during water year 1979. Of that quantity, 170,593 acre-feet of drainage waters were Normally, daily releases are made from bypassed for salinity control pursuant the storage reservoirs in the Lower Basin to provisions of Minute No. 242 of the to meet the incoming orders of the water International Boundary and Water user agencies. All water passes through Commission. the powerplant units. The daily releases are regulated on an hourly basis to meet, as closely as possible, the power loads of the electric power customers. Minimum daily flows are provided in the river to maintain fishery habitat. Adjustments to

22 Flood Control

Lake Mead The "Temple", Lake Mead Lake Mead is the only reservoir on the Williams River and Painted Rock Dam on Colorado River in which space is exclu­ the Gila River (both in the Lower Basin) sively allocated for mainstream flood con­ received unusually large amounts of flood trol. Flood control regulations for Hoover inflow during the winter months. As a Dam are being updated and revised by result of flood control protection within the Water and Power Resources Service the basin, major flood damages were and the Army Corps of Engineers with prevented in the Palo Verde ($3.0 million), the consultation and advice of State and Yuma ($2.0 million), Parker ($1.3 million), local interests. and Gila ($1.2 million) areas along the lower Colorado River. An interim agreement on flood control regulations prior to the formulation and Flood control storage space will be main­ approval of the revised regulations takes tained in Lake Mead as stipulated in the into account the available effective space new interim agreement between the in CRSP reservoirs as well as in Lake former Bureau of Reclamation and the Mead. Modified terms for this agreement U.S. Army Corps of Engineers. This agree­ will go into effect during calendar year ment was also formulated with the con­ 1980. sultation and advice of State and local in­ terests. Alamo Reservoir and Painted Extensive flood control protection was Rock Reservoir are continuing to be provided by the reservoirs within the drawn down and, barring further inflow, basin during water year 1979. Several will each reach minimum flood control severe storm systems swept across the elevations during 1980. watershed and saturated wide areas with damaging rains. In addition to the main­ stem structures, Alamo Dam on the Bill

23 Beneficial Consumptive Uses

Thermal powerplants Grapefruit harvest, Palo Verde Valley, Calif. Upper Basin Uses and Losses About 5.5 million acre-feet of water were provide for releases at Parker Dam; to Agricultural use within the drainage added to storage in Upper Basin supply diversion requirements of the basin, diversion for all purposes to adja­ mainstem reservoirs during 1979. This MWD, miscellaneous contractors, and cent drainage systems, and evaporation water will be released to the Lower other users; to offset evaporation and losses from all reservoirs are the three Basin in future years as required by the other transit losses between Davis and largest categories of depletion in the Up­ Colorado River Basin Project Act and the Parker Dams; and to maintain the per Basin. During water year 1979, agri­ laws, compacts, and treaties upon which scheduled levels of Lake Havasu. cultural and municipal and industrial the operating criteria were promulgated depletions in the Upper Basin were esti­ pursuant to Section 602(a) of the Act. During water year 1979, releases of mated to be 2,700,000 acre-feet. Approx­ 7,388,000 acreMfeet were made from Lake imately 640,000 acre-feet evaporated from Lower Basin Uses and Losses Mead at Hoover Dam to regulate the mainstem reservoirs in the Upper Basin During water year 1979, 6,729,000 acre­ levels of Lake Mohave and to provide for and approximately 600,000 acre-feet were feet of water were released from Lake the small uses and the losses from this diverted to adjacent drainage basins. It is Havasu to meet the requirements for reservoir. In addition, 107,000 acre-feet estimated that an additional 160,000 acre­ water deliveries at Imperial Dam, as well were diverted from Lake Mead for use by feet evaporated from other reservoirs and as those of the Colorado River Indian Lake Mead National Recreation Area, stockponds in the Upper Colorado River Reservation near Parker, Ariz., the Palo Boulder City, Basic Management, Inc., Basin, for a total annual depletion of Verde Irrigation District near Blythe, and contractors of the Division of Colo­ 4,100,000 acre-feet. Calif., other miscellaneous users along rado River Resources, State of . the river, and transit losses between During water year 1979, the total releases Consumptive uses and losses in the Up­ Parker Dam and Imperial Dam. and diversions from Lake Mead were per Basin for the 5 years beginning with 7,495,000 acre-feet. The 688,500 acre-feet 1971 are summarized in the following The major water diversion above Parker anticipatory releases from Hoover Dam table: Dam was made by The Metropolitan Water also were passed through Davis and District (MWD) of . Parker Dams. MWD pumped 783,000 acre-feet from Year 1,000 acre-feet* Lake Havasu during water year 1979. This Lower Basin consumptive uses and included 890 acre-feet for delivery to the losses for the 5-year period ending in city of Tijuana pursuant to a contract for 1975, as published in the "Colorado River 1971 3,413 temporary emergency delivery of a por­ System Consumptive Uses and Losses 1972 3,500 tion of Mexico's Treaty entitlement. Dur­ Report" were as follows: 1973 3,403 ing water year 1979, releases of 7,646,000 1974 3,819 acre-feet were made from Lake Mohave to 1975 3,653

*Published in the "Colorado River System Consumptive Uses and Losses Report" for the 5-year period ending in 1975 Harvesting hay, Utah Oil refinery

Year Mainstream1 Tributaries2 Lower Basin Water Passing total to Mexico

(1,000 acre-feet) 1971 7,795 3,759 11,554 1,561 1972 7,959 4,096 12,055 1,600 1973 7,766 4,267 12,033 1,594 1974 8,315 4,470 12,785 1,721 1975 7,693 4,482 12,175 1,656

11ncludes reservoir and channel losses. 21ncludes uses supplied from ground water overdraft.

For water year 1980, a release of Consumptive uses by small users, river 7,302,000 acre-feet from Lake Havasu has losses or gains, and reservoir losses be­ been projected, including consumptive tween Davis Dam and Parker Dam are use requirements in the United States projected to be a net loss of 211,000 acre­ below Parker Dam, transit losses in the feet. river between Parker Dam and the Mex­ ican Border, Treaty deliveries to Mexico There are no major users between Hoover and the 700,000 acre-feet additional Dam and Davis Dam. During water year releases from Hoover Dam. 1980, consumptive uses by small users, river losses or gains, and reservoir losses During water year 1980, The Metropolitan between Hoover Dam and Davis Dam are Water District of Southern California is projected to be a net gain of 60,000 acre­ expected to divert 773,000 acre-feet by feet. The net diversions from Lake Mead pumping from Lake Havasu. are projected at 105,000 acre-feet. Evap­ oration from Lake Mead is expected to be about 926,000 acre-feet and net gain be­ tween Glen Canyon Dam and Lake Mead is expected to be about 872,000 acre-feet.

25 Water Quality Operations

Partly constructed salinity by-pass drain, U.S.-Mexico border Desalting facility, Gila Gravity Main Canal Since water quality aspects of Colorado Under the provisions of Minute No. 242, In recognizing the need to manage water River operations are extensively de­ the Republic of Mexico is entitled to quality of the Colorado River, it has been scribed in the biennial series of reports receive at water of a quality recommended that long term §alinity in­ entitled "Quality of Water, Colorado River no worse than 115 parts per million (p/m) creases in the river be controlled through Basin," only minimal discussion of this (± 30 p/m) greater than that arriving at a water quality improvement program aspect of operation is presented in this Imperial Dam. Due to the additional generally described in the Water and report. Report No. 10 of the biennial releases from Hoover, Davis, and Parker Power Resource's report, "Colorado River series will be issued in January 1981. Dams and the flood control releases from Water Quality Improvement Program," Alamo Dam on the Bill Williams River and dated February 1972, and a status report During water year 1979, the United States from Painted Rock Dam on the Gila River, of the same title dated January 1974. , bypassed only 3.4 acre-feet to the Col­ the quality of water delivered above orado River below Morelos Dam and Morelos Dam during water year 1979 was The program calls for a basinwide ap­ 170,590 acre-feet through the Bypass only about 762 p/m. The average salinity proach to salinity control while the Upper Drain for a total of 170,593.4 acre-feet of the waters reaching Imperial Dam Basin continues to develop its compact which was replaced with a like amount of during water year 1979 was 816 plm, apportioned waters. The initial step other water, pursuant to Minute No. 242 resulting in a salinity differential of ap­ towards improvement of the quality of the of the International Boundary and Water proximately - 54 p/m. river's water was authorization by the Commission. Congress (Public Law 93-320) of the Colo­ Due to the large amount of Colorado rado River Basin Salinity Control Project, River infiltration to the Wellton-Mohawk June 24, 1974. Irrigation and Drainage District, it is ex­ pected that all drainage wells will be pumping at a maximum rate. As a result, the total flows in the bypass drain during water year 1980 are estimated to be 200,000 acre-feet. No bypass waters are expected to be returned to the Colorado River below Morelos Dam during water year 1980.

26 Enhancement of Fish and Wildlife

Blue Heron chicks Gunnison River, Colo. Upper Basin Flaming Gorge Penstock Intake Despite inconclusive results, it appears For the benefit of fish habitat, the interim Modification that there was a significant improvement operating rules for Fontenelle Reservoir The shutter system of the three selective in fish growth this past season. Rainbow provide a continuous flow of at least 300 withdrawal structures, now part of trout planted in the Green River below ft3/s in the channel immediately below Flaming Gorge Dam, went into operation the Dam-from Greendale to Indian Fontenelle Dam. During water year 1979, on June 20, 1978, and was found to func­ Crossing at the head of Browns releases for power production and other tion properly. It affects the downstream Park-have grown approximately four in­ purposes provided flows of at least 500 water temperatures as predicted by with­ ches during the five-month period during ft3/s. drawing water from the warmer surface which the withdrawal structure was in level of the reservoir. Water released last operation. By comparison, the 1977 A release at least 76 ft3/s throughout the summer was at a constant 56 0 F until the growth reports noted a one-half inch winter of 1976-77 assured good fish reservoir surface started to cool in the growth during an eight-month period; and habitat in the river below Taylor Park and fall. When the surface temperature ap­ in a 1976 report, three inches of growth Blue Mesa Reservoirs. Coordinated opera­ proached 39 0 F, the lower shutters on the during a 12-month period was recorded. tion between Taylor Park and Blue Mesa 30- x 30- x 200-foot withdrawal structure Cutthroat trout showed a similar growth Reservoirs in delivering irrigation water to were used to maintain the 39 0 F rate increase. Rainbow trout stocked in the Uncompahgre Project provided addi­ temperature until spring when the surface 1978 almost doubled in weight, and both tional fishery and recreational oppor­ water temperature begins to rise. The up­ the catch rate and the number of fish in tunities between the two reservoirs. The per shutters on the structures are used the creel increased significantly. interim operating rules specify a during the warm months to raise the minimum of 200 ft3/s to maintain fish temperatures of the downstream water These changes indicate that the fish are habitat below Crystal Dam and below the releases by withdrawing water from the feeding more actively since the water Gunnison Tunnel. warm upper layers which range in depth temperature increase. There has been a from 40 to 70 feet. significant increase in the numbers of in­ A continuous flow of at least 530 ft3/s vertebrates, commonly called scuds, on was maintained throughout the year im­ Operation of the penstock modification which trout feed. These are the same in­ mediately below Navajo Dam for fish has already resulted in some apparent vertebrates that populate the Colorado propagation. changes in the downstream fishery. River below Glen Canyon Dam and sup­ However, studies documenting the port one of the top trout fisheries in the Clear water and a minimum release of fishery changes, being conducted by the western United States. 1,000 ft3/s provided good habitat for in­ Utah Division of Wildlife Resources and troduced species of fish in the river BiolWest, Inc. under a three-year contract below Glen Canyon Dam. with the former Bureau of Reclamation, report that results are not yet conclusive and that definitive measurements of the fishery are not yet avai lable. 27 Canadian Geese Great Blue Heron

Other changes indicate the downstream The Fish and Wildlife Service has con­ Lower Basin fishery is improving. For example, catfish ducted preliminary examinations of During the 1979 bass spawning season, are being caught at Little Hole and carp several Water and Power projects under the Lake Mead water level declined ap­ are now in the river where they have not the formal Section 7 consultation proximately 5 feet and temperatures were been recorded for a number of years. The procedures, as provided for by the cooler than the previous year. Bass increased water temperature also appears Endangered Species Act of 1978 as nesting on the Nevada side was good, to be affecting the composition and amended. Conclusions from these initial with a 48 percent nesting success, but reproduction of fish species in Ladore examinations and other documentation nesting was not as frequent or as intense Canyon and as far downstream as indicate that the proposed actions may this year as last. Nesting attempts were Jensen, Utah. Precise changes are not jeopardize the continued existence of fewer this year in portions of the Arizona yet known but will be analyzed and both fish species. Fish and Wildlife has side, possibly due to a shorter spawning reported when the three-year study is stressed the need for Water and Power to period. However, there was increased completed in 1980. develop additional data on the habitat re­ nesting in other portions of the Arizona quirements of these species. Therefore, a side, possibly because of increased Fishing activity was the highest last year team has been charged with studying the habitat. Arizona had an overall sucess si nce 1970 and other recreational use, problem and preparing the necessary rate of approximately 37 percent, which especially rafting, has also increased. biological opinions and assessments. represents a decrease of 1 percent from last year. However, the success rate was The Water and Power Resources Service The team will determine habitat re­ higher than 2 years ago. and the Fish and Wildlife Service are quirements, monitor existing habitats, presently consulting over the impacts of and expand life history information on To provide satisfactory fish habitat along various water development projects on the endangered Colorado squawfish and the lower river and in Lake Havasu, endangered Colorado River fish, specifi­ humpback chub. The study will be con­ releases from Lakes Mohave and Havasu cally,the Colorado squawfish (Ptycho­ ducted on the Green and Colorado Rivers were regulated so that minim4,m flows cheilus lucius) and humpback chub (Gila above Lake Powell. were 2,000 ft3/s and the level of Lake cypha). Havasu remained relatively stable during the spring spawning season.

28 Preservation of Environment

Topock March dredge A dredge on the Lower Colorado River. Preservation or enhancement of the en­ proposals for several large thermal elec­ wildlife, will assist management deci­ vironment is a matter of high importance tric generating plants cooled with water sions on water savings in the irrigation in the planning, construction, and opera­ and for coal gasification plants using disticts. tion of all Colorado River storage water from Water and Power facilities in features. Contracts for water services, the Colorado River system have required The Water and Power Resources supplies, grants of rights-of-way and in­ special consideration to protect the en­ Service's 12-inch dredge "Little Colorado" dentures of leases for use of Federal vironment of the area. The Secretary of spent several months in Beale's Slough land, and participating agreements ap­ the Interior's responsibility for water just south of Needles, Calif., creating a proved by the Secretary of the Interior in­ pollution control has been delegated to back-water with scalloped banks for cude language to control water and air the Commissioner of Water and Power fisheries. This project was developed by pollution, to require restoration and Resources and redelegated to the Re­ the Bureau of Land Management and the reseeding of lands scarred by construc­ gional Director of the Upper Colorado California Department of Fish and Game tion and operation activities, and to Region. The Regional Director of the to enhance fisheries along the lower encourage conservation of the aesthetic Lower Colorado Region has been dele­ Colorado River. beauty of nature. gated responsibility for water pollution control at the Mohave Powerplant. The Hoover Powerplant Modification In­ In operating the reservoirs of the Colo­ vestigation, being conducted to study the rado River system, releases from This past year was the second year of a feasibility of increasing the electrical out­ Fontenelle Reservoir are scheduled so 3-year study, jointly funded by the Water put of Hoover Dam to provide greater the flow pattern wi II not adversely affect and Power Resources Service and the peaking power, is continuing. This modifi­ the downstream goose nesting areas. Fish and Wildlife Service. The study is cation study, if implemented, would Minimum flows are maintained below all designed to develop vegetation manage­ change the releases from Hoover Dam, dams to provide a desirable habitat for ment procedures for the lower Colorado which in turn would affect the fisheries fish, animal, and plant life. Flood control River. The study program will replant below the dam. Studies are now in prog­ operations at Navajo Reservoir and Lake native riparian communities in selected ress to determine what these affects Mead protect the downstream channels spots to determine the economic and would be. These data will be collected and flood plains from erosion and scour­ biological feasibility of reestablishing and evaluated before any modification is ing during periods of high flow. Recent native riparian communities along the made. lower Colorado River.

The first year of a 3-year study was spent on the relationship between wildlife pro­ ductivity and irrigated agriculture on the lower Colorado River. This study, which is assessing the influence of agriculture on 29 Power Operations

Crystal Dam, Colo. Upper Basin- Water Year 1979 Revenue Colorado River Storage Project (CRSP) Firm Energy Sales $39,900,000 Sources of Energy Nonfirm Energy Sales The following table summarizes the (Oil Conservation) 9,062,000 CRSP generation, purchases, disposition, Net Generation kW·h Hoover Def. and revenue from power operations for Flaming Gorge 480,236,000 reimbursement 500,000 fiscal year 1979. The last part of the table Blue Mesa 332,449,000 Parker-Davis firming 2,293,000 is a projection for fiscal year 1980. Morrow Point 442,904,000 Wheeling for others 3,040,000 Fontenelle 63,846,000 Miscellaneous Income 300,000 The total revenue from power operations Glen Canyon 3,829,791,000 $55,095,000 in fiscal year 1979 was $58,095,000. For Crystal 223,285,000 fiscal year 1980 it is estimated to be Subtotal-Net Generation 5,372,511,000 Water Year 1980 $72,500,000. This increase is anticipated Purchases (for) partly because of an estimated power Hoover Deficiencies 549,296,000 Estimated Energy Sales 6,489,000,000 rate increase and partly because of in­ Parker-Davis firming 63,658,000 Estimated Purchases 1,000,000,000 creased sales resulting from oil conserva­ Rio Grande firming 10,523,000 Estimated Peaking Capacity Sales tion. CRSP firming 420,951,000 Winter 79/80 375,000 kW Fuel Replacement 287,880,000 Summer 80 183,000 kW Subtotal Purchases 1,332,308,000 Estimated Revenues $72,500,000 Transmission for others 134,517,000 Total Energy Receipts 6,839,336,000

Disposition of Energy

Firm Energy Sales 5,467,000,000 Nonfirm Energy Sales (Oil Conservation) 287,880,000 Del. to Hoover allottees 549,296,000 Parker-Davis 63,658,000 Rio Grande firming 10,523,000 Net Interchange 141,408,000 System Losses 319,571,000 6,839,336,000

30 Generator rewinding, Glen Canyon Powerplant Generating Unit Maintenance GC -1 GC-2 - GC-3 - GC-4 - - GC-5 - GC-6 - ~ GC-7 ~ GC-8 - F.G. - 1 F.G. - 2 F.G. - 3 8.M. -1 8.M. -2 M.P. -1 - M.P. - 2 - Crystal -- IFontenelle Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Sep. Fontenelle~ - Crystal - M.P. -1 - - M.P. - 2 - -I--- 8.M. -1 I- o - co "- ~ 8.M. -2 F.G. -1 - (J) > ~~ F.G. - 2 -r-- c: c: :::::> .- F.G - 3 Q) - og IG.C -1 c: ctS ._ c: ..- +J Q) G.C. -2 co C - ~ .- Q) ctS G.C. -3 c: ~ G.C. -4 Q) (; = CJ:;; G.C. - 5 0-3 G.C. -6 - (/)-0 rn a:~ G.C. -7 uas IGC. -8 - I- Power Operations

Parker Dam, Ariz.-Calif. Davis Dam lower Basin Hoover Dam have been estimated to ex­ During water year 1980, the Parker Dam ceed minimum downstream requirements. Powerplant will be modified for remote Water Year 1979 These include diversions by The Metro­ automatic control for the four As discussed in the section on additional' politan Water District, and comply 30-megawatt units and Davis Dam will releases, on April 27, 1979, the Secretary with the overall requirement to meet have remote automatic control completed of the Interior declared that extra water Compact and operating criteria release for three of its five units. An inspection would be released from Hoover Dam to provisions. The excess water will and preventative maintenance program is reduce the probability and magnitude of generate 100 percent of defined firm carried out during the time each of those mandatory flood releases in1979 or 1980. energy. The estimated monthly Hoover units is out of service for the installation releases during the operating year total of the remote control equipment. . The total energy delivery to the Hoover 8,496,000 acre-feet. It is estimated that allottees during the operating year ending generation from these Hoover releases, May 31, 1979, was 3,838,327,402 kilowatt­ along with the interchange between hours (kW-h). Of this total delivery, Hoover and Parker-Davis interchange, will Hoover generation plus Parker-Davis inter­ result in delivery to the allottees of about change amounted to 3,287,243,402 kW-h 3,962,080,000 kW-h of electrical energy. and replacement energy amounted to 551,084,000 kW-h. No deficiency power purchases have been budgeted for operating year 1980. Water Year 1980 In operation studies of Lake Mead and All scheduled periodic maintenance at Lake Powell for the Hoover operating year Hoover, Davis, and Parker Dams was per­ which ends May 31,1980, the releases at formed in water year 1979. The program for installation of high pressure thrust bearing lubrication will be completed dur­ ing water year 1980 for all generating units at Hoover Dam.

The lower Nevada penstock at Hoover was scheduled to be out of service for approximately three weeks starting December 1, 1979. This measure was for the purpose of inspection and repair of the penstock lining.

32 ~u.s. GOVERNMENT PRINTING OFFICE: 1980-0-678-524 As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our na­ tionally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving the environmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recrea­ tion. The Department assesses our energy and mineral resources, and works to assure that their development is in the best interests of all our people. The Department also has a major responsibil­ ity for American com­ munities and for people who live in Island Territories under U.S. administration.