WSP09130

• File Number: 8200.300.20.F
• Description: Grand Canyon Protection Act
• Basin: Colorado Mainstem
• Date: 1/1/1994
• Author: Michael Conner
• Title: Extracting the Monkey Wrench from Glen Canyon Dam: The Grand Canyon Protection Act - An Attempt at Balance
• Water Supply Pro - Doc Type: Report/Study

144

PUBLIC LAND LAW REVlEW-_

[Vol. 15

1994J

GRAND CANYON PROTECTION ACT

145

2. Glen Canyon Environmental Studies and the Effect oj Dam
Operations

deposits must come from tributaries within the Canyon.ss The National
Park Service is concerned with decreases in the size and number of
sandbars since construction of the dam.'f In fact, the National Park
Service has designated preservation of sandbars as one of its highest
priorities.'l'O This priority is understandable, considering the importance of
sandbars as habitat for riparian lifelI and as campsites. '72 If sandbars are to
be maintained in the Grand Canyon, releases from the dam will have to be
planned so that they build up the sandbars without causing a net loss of
sand-size particles. 'I'll
In addition to the dam's impact on sediment fiof's, differences in the
temperature and clarityofthe water have had a tremendous effect on plant
and animal life downstream of the dam. Sunlight-the most important
source of energy for plant and animal growth--can now penetrate the clear
water. This causes a tremendous increase in the growth of algae, H the basis
of the river's food chain.1ll Thus, the Colorado River through the Grand
Canyon is much more biologically active than it was in its pre-dam
condition.
Probably the most controversial result of this change in biology has
been the emergence of the Colorado River as a world-renowned trout
fishery at the expense of native fish species, Glen Canyon Dam, although
not solely responsible for this change, has certainly played a significant role
in the process. Before the early 1900s, the dominant fish were squawfish,
one of three chub species (humpback, bony tail, or round tail), and

Widely fluctuating flows from Glen Canyon Darn appear to harm the
downriver environment in many ways. Th,eJirst attempt to investigate thi~
harm began in 1982 with the Gle~,j~iinYOI). EnvirqDInental Studies
(GCES) program, initiated as an envirdnmental assessment of the effects
of up rating and rewinding the eight generators in place at the dam,60 The
broad objectives of the program were to (1) determine the impacts of dam
operations on the natural and recreational resources of the Grand Canyon,
and (2) decide whether there were ways, within the mandates of the
CRSPA and the law of the river,61 to adjust operations so as to minimize
downstream impacts,611
To date, the program has identified a number of impacts. Records
indicate that before Glen Canyon Dam was built, the average annual flow
through the Grand Canyon varied from a maximum range of 85,000-
95,000 cfs during spring runoff, to a minimum of about 4,000 cfs.u The
dam eliminated these seasonal extremes, replacing them with daily
extremes of 1,000 to 31,000 cfs. The dam also destroyed the seasonal
temperature patterns of the river. Before the dam, temperatures ranged
from a winter lQw of approximately 40 degrees Fahrenheit, to 60-70
degrees in the spring, and a high of7 5-85 degrees in the summer.64 Now the
water released from Glen Canyon Dam comes from the bottom of Lake
Powell, and its temperature stays nearly constant at about 48 degrees.611
The most significant result of the new flow regime is the alteration of
sediment flow through the Grand Canyon. For millions of years, the
Colorado River and its tributaries have deposited and removed sediment
from the canyon in a complex pattern of erosion and deposition." Glen
Canyon Dam interrupted this pattern by trapping sediment in Lake
Powell, The dam's effluent is now clear and free of sediment and thus has an
enormous potential to erode (especially at high flows) but little ability to
deposit.67 Consequently, the only sediment available to replenish eroded

68. Id. at 52-54. !
69. GCES COMMITTEE,supranote8,at 68. One investigator attributes the majorcauseo -beach
erosion to the great !toad of 1983, which resulted in the opening of the spillways at G]en Canyo.. Dam
IInd outflows exceeding 92,000 cfs. C...ROTHERS & BROWN, supra note 29, at 28. This extremely high
rate of flow, not carrying a significant al1lount of sediment, resulted in cha ngedbeachprollles.Since
that time, the beaches within Grand Canyon have consistently eroded.ld. at 57-59. Of twenty beaches
studied since the 1970s, four were gone by 1985,andelevenothersha d significantly decreased in size.
Only three had actually gained sand./d. at 58.
70. GCES COMMITTEE, supra note 8. at 68.
71. Notwithstanding the erosion of sandbars, riparian habitat has henefittedsomewhat from the
presence of the dam. Controlling the e",tremes of water flow through the Canyon has resulted in
stabilityforsomerip:arianareasandallowedforagreaterabundanceoffoodresources. resulting in an
increase in numbers and species of animals along the river. CAROTHERS & BROWN, supra note 29, at
117-28.]48.
72. Id. at 59. Recreationists must also contend with the daily change in flows. River runners
. mU5t sometimes choose between scheduling runs at low water stage. when they might he confronted
withexposedrocksinthechannel.oratahigherstagcwhenlarger.moredangerouswavesarepresent.
Id. at 37.
73. GCES COMMITTEE, supra note 8. at 68.
74. Id. at 65.
75. CAROTHEiIS & BROWN, supra note 29, at 64. Other physical and chemical factors affecting
aquatic productivity are water temperature, nutrient levels. water fluctuations, bank and bottom
conditions, substrate stability. and water velocity. Eaehofthcse factors has bcen affect edbyre]eascs
from Glen Canyon Dam. Id. at 65. '"

60. GeES COMMITTEE, supra note 8, at 227.
61. The law of the river consists of the set of compacts, statutes, and court de<: isionsallocating
thellowoftheColorado Riveramongstatesandbetween tbe United States and Mexico. Gctches,suprQ
note 10. at 414.
62. Id. at 229.
63. CAROTHERS & BROw/'I, suprQ note 29, at 22.
64. Id. at 67. "
65. Id. All elfe<:l.S of the dam, however. disSipate downstream of the Glen Canyon due to
additiona1llows from natural downstream tributa~ies. ld. at 71.
66. ld. at 47.
67. ld. at 52.

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