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Home , Cataract Canyon, Dam, Glen Canyon, Glen Canyon Dam

THE EFFECTS OF

ON THE .

by

Margaret Gebren

A SENIOR THESIS

m

GENERAL STUDIES

Submitted to the General Studies Council in the College of Arts and Sciences at Texas Tech University in Partial fulfillment of the Requirements for the Degree of

BACHELOR OF GENERAL STUDIES

Approved

Dr. JeffLee Depal'tmenr of Economics and Geography Co-Chair of Thesis Committee

Dr. Rob Mitchell Department of R WFM Co-Chair of Thesis Committee

----~~------Dr. Dale Davis Director of General Studies

May 1999 /ILZ ''55< ' /

7 3 ACKNOWLEDGMENTS

I wish to express my deep gratitude to Dr. Lee and Dr. Mitchell for taking time out to read and critique my work and also for their commitment to teaching, which is greatly underrated. Thanks also to my family, for graciously correcting my grammar and spelling all these years! OF CONTENTS

ACKNOWLEDGMENTS ii CHAPTER I. INTRODUCTION 1

II. HISTORY OF THE DAM 4 III. LIFE BEFORE THE DAM 7

IV. FORMATION OF THE 9 V. LIFE AFTER THE DAM 14

Lake Powell 14 Releases 15

Rapids 16 Sand and 16 Vegetation 17

Backwaters 18 Water Chemistry and Temperature 18

Heavy Metals 19 Salinity 20 Endangered Species 21

VI. THE PLAN 24 VII. THE EXPERIEMENT 27 VIII. RESULTS 30

Sandbars and Sediment Transportation 30

Rapids 31

ni Camping Beaches 31

Backwater 32 Geochemistry 33

Fisheries 33

Riparian Vegetation and Resources 34

Cultural Resources 34 IX. CONCLUSIONS 35 BIBLIOGRAPHY 36

IV CHAPTER 1

INTRODUCTION

Mankind has become so used to controlling nature that we often forget or over-look the consequences of our handiwork. Such is tme in the case of the . Since the 1960's Dam, located on the Colorado River, has been operated in such a way that it has changed the downstream community of the river. It was not until the 1980's that scientists began to take a serious look at just how the dam's operations were affecting the . After much study and discussion, one of the greatest scientific experiments done to date was conducted. On March 26, 1996, an experiment was conducted to test how the dam operations had altered the Colorado River ecosystem.

Scientists, fearing that the Colorado River ecosystem would be changed forever by the current management, proposed an idea. They suggested that a controlled be released from the dam to simulate the natural of the past. The main idea was to observe and to study the effects That Glen Canyon Dam has had on the Colorado River. In this thesis, the question of what have been the environmental consequences of the building of Glen Canyon Dam on the Colorado River will be studied.

It has always been known that floods represent a cleansing and rejuvenation process for a river ecosystem. What scientists and dam operators did not realize was just how much the dam had changed the downstream river community. From studying the formation of the Grand Canyon, scientists had hoped to discover exactly why natural floods were necessary in controlling the equilibrium state of a river. When pre-dam conditions of the river were compared to the conditions of the river after the dam and startling resuUs were discovered. With the backing of Congress and the Office of the Secretary of the Interior, a new era in river management was about to begin.

1 Never before had such an experiment been conducted on a project currently in use. So on March 26,1996, the Bureau of Reclamation opened the dam's spillways in an attempt to re-create a high-flowing flood. Scientists from universities, the US Geological Survey and other agencies set up their equipment to take vital data measurements that would ultimately decide the fate of the Colorado River and Glen Canyon Dam. From their data, new operational procedures would be set to regulate the flow of water through Glen Canyon Dam. Thus, the story of a dam versus a river ecosystem begins.

To tmly understand the significance of the experiment, the history of the Colorado needs to be discussed. As Palmer explains, in 1869 set off on the last great scientific expedition of the continental . After battling the wild and unpredictable Colorado River, he became set on damming and irrigating the desert lands of the Western United States. After being named the Director of the United States Geologic Survey (USGS), he wrote that the water from the Colorado River was being wasted. The flood were traveling down and being squandered into the salty sea. Why throw away all this water instead of harvesting it for human consumption? Man was powerfiil enough to reap the benefits the river provided, so why not develop the surrounding areas? Even though he believed that the West should be settled, he cautioned against indiscriminate settlement. He proposed that the government should set aside and reserve possible dam sites for the settlements and that districts be organized. Even though he became a hero to dam builders and river mnners, people did not listen and did not plan their communities very well. (Palmer, "Lifelines" 78-79)

Frontiersmen set up residence in areas around the river, and then began to move fiirther and further away, taking the river with them. Palmer notes that channels and aqueducts were built to siphon the water to desired territories. In 1922, the Colorado River Basin Compact was established, dividing the river into two regions. Through the

2 agreement, the compact allocated water equally among the specified basins. The upper basin, consisting of Colorado, and New , shared the with the lower basin of , and . In addition to these allocations, a contract was made with Mexico guaranteeing stream flows for Mexican irrigation.

When the West was settled. Palmer goes on to say, it was established with a frontier outlook. The people believed that the land should be colonized and subdued at all costs. The waterways were thought to exist expressly for the people and their needs. Desert lands were to be turned into an environment like that of the East, wet and rainy. To achieve this goal, the Bureau of Reclamation (BOR) was created to populate the West by selling subsidized water for whatever price the farmers could afford. The land was planted, and the Colorado river was used for drinking and irrigation water.

When was advanced enough, the decision to build a dam was set in motion. In 1916, the first survey of the Colorado had identified a possible dam site in Glen Canyon. It was not until 1957 that the constmction of the dam began. With constmction of the dam, so begins the story of a river's demise. It is a story that caused 180 miles of the Colorado River and scores of to be flooded (Palmer, "Lifelines" 13). It is a story that tells how a dam can alter a fragile and dynamic river ecosystem, which this thesis will present. CHAPTER II

HISTORY OF THE DAM

It is no coincidence that represent a change to life on immediate downstream river systems. Their presence on has caused a rippling affect, altering the life of the community located beneath. Rapids, stream vegetation and become flooded and currents stop. These changes bring variations in water temperature, species adaptation and water chemistry (Palmer, "Endangered Rivers" 21-29). If dams cause so many alterations, then one might ask why they are built in the first place. The answer to that is for human requirements. The people of the Southwestern United States depend heavily on the Colorado River and Dam system for their water and electricity needs. Because of this, Glen Canyon Dam was buih.

By modem standards, Glen Canyon Dam is quite remarkable. It is only one of fourteen major dams built in the United States before the National Environmental Policy Act of 1969 was signed into law. The policy required an environmental review or impact statement to be conducted to assess the ramifications of the proposed project. Because no such study was conducted, the outcome of the dam would not be realized until many years later (Wegner 1-2). Glen Canyon Dam was constmcted about fifteen miles upstream of Lee's Ferry and twelve river miles downstream of the Arizona-Utah state line. With its constmction, the creation of the second largest in the United States came into existence. .

By itself. Lake Powell is quite impressive. It extends 186 miles upstream and has a total storage capacity of 27,000,000 acre feet (U.S. Dept. of Interior. BOR. Glen Canyon Dam, Arizona 1-2). 1,960 miles of shoreline are touched by the lake. Water is supplied to twenty million people and electricity to 800,000 households or five-and a-half miUion customers (Forbes 28). However, it was the constmction of Glen Canyon Dam that created Lake Powell.

Glen Canyon Dam is named after the canyon in which it was built. It is the fourth highest dam in the country and the twenty-second highest in the world. When completed in 1964, it had a stmctural height of 710 feet, a crest of 1560 feet and contains 4,901,000 cubic yards of . The crest width is twenty-five feet, while the base width is three-hundred feet. The geology consists of sandstone that forms the canyon walls. The sandstone is particularly uniform and homogeneous. Its texture is medium to fine grained and moderately hard to soft. The porosity is moderate and highly absorptive, which creates high capillary due to the small size of the intergranular pore spaces (U.S. Dept. of Interior. BOR. Glen Canyon Dam, Arizona 1-2). The porosity of the , means the amount of fluid it is able to hold in-between its grains. Because the sandstone is moderate and highly absorptive, it is able to draw-in a sizable amount of water. This is not entirely a desirable trait because water is able to escape the reservoir into the sandstone supporting the dam. As impressive as it is, the Glen Canyon Dam was not built as a technological marvel. The people who built it had other intentions.

Glen Canyon Dam was created for two main reasons: and electricity. Only after these two were accomplished was the last consideration of natural and cultural resource protection taken into account ("The Big One" 65-66). The electricity for the people of the Southwest comes from the power plant located within the dam. Hydroelectric power is produced by the movement of water through the power plant. Eight generating units provide a total generating capacity of 1,042,000 kilowatts. Water is conveyed from the reservoir to through eight fifteen-foot diameter penstocks embedded within the dam (U.S. Dept. of Interior. BOR. Glen Canyon Dam, Arizona 1-2). Main components of the power plant include four river outlet conduits located near the left abutment of the dam. They are the controls from which water is released for downstream commitments when the power plant is not in operation and to assist in making releases during natural floods. The conduits from which water is released are ninety-six feet in diameter with a total capacity of 15,000 cubic feet per second. The units of cubic feet per second, or cfs, is used as the measurement of water volume. In the experimental flood, different water volumes (measured in cfs) will be released and compared to show how different volumes affect the river system. Spillways consist of the approach channels, intake stmctures and inclined . Water is transmitted to a horizontal tunnel and a downstream defector bucket to drive the water towards the center of the river. Thus the total spillway discharge equals 276,000 cfs. (U.S. Dept.of Interior. BOR. Glen Canyon Dam, Arizona 1-2). It is this complex system that has put a strain on the Colorado River and the ecosystem it flows through.

To understand how the river has changed since the building of the dam, the basic components of pre-dam life have to be examined next. CHAPTER III

LIFE BEFORE THE DAM

The Colorado River begins in the steep upper reaches of the Rocky . These streams are no more than rocky channels with very few . Lower down, the river flows through broad valleys in Southern California and Northern Mexico on wide floodplains. Here the water is used by agricultural industries to irrigate their fields of crops. In between these areas lies the Grand Canyon. The Colorado River flows through steep rock-bound canyons in a channel barely wide enough to fit on the basin floor (Graf 17). Each spring when the snow in the Rocky melted, it would send floods racing down into the canyon. On average, the peak of the spring discharged equaled about 934,000 cfs (Anderson, Graf, Marzolf 1-4). Towards the end of the summer and eariy fall, only about 3,000 cfs flows were typical (U.S. Dept. of Interior. Geological Survey. Western Region. Effects of Glen Canyon Dam on Water 1-2).

The force of the constant floods was able to keep the growth of most perennial river vegetation to a minimum and the flow of nutrients constant (Cone 34-40). Eight native and several non-native fish species lived within the confines of the river ecosystem (U.S. Dept. of Interior. Geological Survey. Western Region. Effects of Glen Canyon Dam on Fish 1-2). Sediment load increased during the spring mnoff and then again in the late summer from the mnoff in the tributaries (U.S. Dept. of Interior. Geological Survey. Western Region. Effects of Glen Canyon Dam on Water 1-2). When the floodwaters receded, the sediment was scoured and redeposited. Sandbars were built and beaches were given a fresh dose of sand. Flood waters kept the sandbars clear of vegetation and also enabled the of polluted beaches to be replaced by unsoiled sand deposits. (Anderson 1-3). On average, the river was able to carry sixty-six million tons of sediment to the head of the Grand Canyon and then dispersed the sediment downstream in many different areas and habitats. Backwater areas were created and continually cleaned for fish habitation. The water was warmed and rich in sediment, and the turbulent waters acted as a cleansing agent ("The Big One" 65-66). The turbulent waters are able to flow in different velocities, creating random water fluctuations that stir-up and mix the water with a fresh supply and thereby cleaning stale and stagnate water. The result was that the Colorado ecosystem evolved under a seasonally dynamic hydrology of spring floods (Wegner 1-4).

Yet all this was about to be altered by the daily operations of the dam, for next matter to be discussed. CHAPTER IV FORMATION OF THE GRAND CANYON

When describing the Cirand Canyon, John Wesley Powell used these words, "...1 am able to observe the wonderful phenomena connected with this flood of lava. The canyon was doubdess filled to a height of 1,200 to 1,500 feet, perhaps by more than one flood... What a conflict of water and fire there must have been here!" (qtd. in Hamblin 34).

Sixty-five million years ago on the area where the Grand Canyon is located, Hamblin notes bulged upwards and a river cut downwards. This is how most people assume the Grand Canyon was formed, from the cutting of the Colorado River. Even though this is the most wildely accepted theory among the public on the formation of the Grand Canyon, other factors played an important role. Besides river erosion, there was continental drift, volcanism and climatic change.(Hamblin 39-40)

Climatic change came from continental drift. The Grand Canyon rests on the North American Plate. At one time this plate was located further south than it is now. Warmer temperatures allowed more water flow, while cooler temperatures caused expansion and contraction of rocks from freezing water. In the geologic past, the North American plate collided with the Pacific plate, causing it to subside beneath the North American plate. The subsidence created the formation of an enormous that grew where the Grand Canyon is today. Through erosion processes, these mountains have eroded away to form the base of the Grand Canyon. (Ribokas 3-6)

One of the main erosion factors that helped aid in the process was the Colorado River. The Colorado River was created by the merging of two rivers: the and the ancient Colorado. Together they worked to carve out a 277 mile long trench known as the Grand Canyon. The initial cutting of the rivers began no earlier than ten million years ago and continues today. To shape the Grand Canyon, the river on average drops at a gradient of no more than 7.8 feet per mile (Wallace 2). However, none of this could have happened without another important natural event. It is this other component that helps us to understand how dams can affect a river and the .

Hamblin's account of the formation of the Grand Canyon is authoritative. He recounts that the significant phenomena that are not as readily recognized are volcanic activity and the lava dams produced within the Grand Canyon. The lava dams are an important part of history because they help to explain how dams affect the river ecosystem. Powell realized that there was more than one force of nature at work when the Grand Canyon was formed. He first viewed the remnants of lava clinging to the walls of the iimer gorge in the western part of the Grand Canyon. Unfortunately, this awesome record of relatively recent volcanic activity (from about 25,000 to more than one million years ago) remains largely unknown.

It is in the Toroweap section of the Grand Canyon where the volcanic activity is observed. A cycle of lava dam formation and its destmction is what helped form the Grand Canyon. Within the deep walls of this canyon area lies a sequence of the Paleozoic strata a mile deep. Clear and distinct major fauUs line the canyon, and extinct volcanoes dot the landscape. There are black falls of "frozen" lava cascading from the canyon rim to the river almost 5,000 feet below. And above it all sits Vulcuns's Throne, a 600-foot cinder cone looking down.

To reach the surface, Hamblin further explains, lava flowed through a massive rock pipe named Vulcun's Forge. The rock pipe, situated in the middle of the river, rises sixty to seventy feet above the water. Throughout the canyon walls, numerous dikes cut their way through, marking the paths of lava flow to the surface. One of the most astounding features is the huge, vertical slabs of black basalt stacked side by side against the canyon

10 walls. Of the ancient lava dams that once blocked the Colorado River and caused huge lakes to form, these are the only remains.

To understand why there was volcanic activity in the Grand Canyon, one must note that the canyon cut across the southern margins of the Uinkaret field. The Uinkaret field is a relatively small volcanic field in Northern Arizona that has been the site of repeated emptions during the last two to three million years. These emptions formed incredible lava flows more than 3,000 feet high that eventually formed dams within the canyon. These dams caused the build-up of large lakes extending far upstream.

From studying the sequence of preserved in the inner gorge, Hamblin notes that scientists distinguished four different types of dams produced during the major periods of volcanic activity. The first type, more than a million years old, was built from several massive flows. Each flow was estimated to be more than 500 feet thick and ten to twenty miles long. Speculated to have reached a height of up to 2,000 feet, these dams were probably the highest ever in the Grand Canyon.

The second type of dams was forged by the rapid accumulation of numerous thin lava flows that were fifteen to twenty feet thick. Due to their low height, the Colorado River immediately overflowed them, depositing gravel and sand beyond its boundaries.

The third type of dams was formed by a series of six to eight lava flows. Each flow was fifty to 200 feet thick. It took extended periods of time (100 to 1,000) years to build just one of these dams. Therefore, each flow became partly eroded before the next flow covered it.

The last type of dams was formed within the last 500,000 years. These lava flows were single flows 200 to 600 feet thick. The most extraordinary feature about these flows was how far they reached downstream. One of the remnants was traced to a distance of more than eighty-five miles downstream.

11 As stated previously by Hamblin, there was the cycle of dam formation and then the destmction of the dams. There were two important aspects of erosion that began instantly after the water overflowed a lava dam. The first was the cutting of a new canyon by normal erosion of the river. The second part was the upstream migration of . The fast erosion action by migration could completely dissolve a lava dam in less than 20,000 years. Because the waterfalls migrated headward, they eventually fractured and fell apart. It is conceivable that some of them may have failed in a single catastrophic event, thus, producing a rapid and tremendous discharge of water and saturated mud and thereby creating a flood. (Hamblin 34-40)

The highest lava dam built a lake larger than the combination of and Lake Powell. It extended upstream from Toroweap through the Grand Canyon to beyond Moab, Utah - a distance of more than 400 miles. (Hamblin 34-40)

Thus, within a few thousand years after volcanic emption produced lava dams, erosion would come along and destroy the dam. This interplay between volcanism and the river shaped the evolution of the Grand Canyon. After every such event, the Colorado River would regain its undaunted position as the supreme geological force in the Grand Canyon.

These natural phenomen gave way to the recognized four-stage life cycle of a dam. The four stages are the constmction of a barrier, the formation of a lake upstream, the filling up of the lake with sediment, and the ultimate destmction of the dam with the retum of the river to its previous condition. These four cycles are the same for all dams. This means that the Colorado River basin, which has numerous dams, will experience the same cycle. All the dams on the Colorado River are now in the third stage of the life cycle, with the lakes behind them filling up with sediment. (Hamblin 34-40)

12 Because a river is part of a dynamic system, a dam cannot remain as a permanent fixture of the landscape. At some point, it will give way. Within 700 to 800 years. Lake Powell will be full of mud. So, in continuation of the massive lava dams demise, so follows the fate of Glen Canyon Dam and Lake Powell. (Hamblin 34-40)

13 CHAPTER V

LIFE AFTER THE DAM

Once a natural and dynamic river, the Colorado River ecosystem is now threatened by the daily fluctuations of water releases from the Glen Canyon Dam. The US Bureau of Reclamation never had the intention of damaging such a fragile environment, but their lack of prior knowledge and experience of water discharges never prepared them for the consequences. Environmental protection laws had not yet been established, and comprehensive studies had never been organized about the possible aftermaths of building a dam. The controlled flood was to be the vital experiment that would make or break the case for a change in dam operations. Before the actual experiment could be carried out, studies had to be performed to see how the downstream river had changed since the dam's completion.

Lake Powell Part of the problem is Lake Powell, the reservoir formed behind the dam. It took sixteen years to completely fill. Consequences of the reservoir were many. When it flooded. rapids were immersed beneath the water, and some of the most beautiful river-bank desert scenery was washed away ("The Big One" 65-66). Several Indian Ruins were either inundated or threatened by the reservoir. The deep water of the lake acts as a shield in keeping the sunlight from penetrating to the bottom. Without sunlight, bacteria growth stops as well as other essential building blocks in the aquatic food chain. Creatures that depend on the currents to deliver the nutrients suffer from a lack of food. Warming of the surface occurs from the sun, which enhances eutrophication. This is a process in which an over-fertilization of algae occurs, which in turn stifles life by using up the oxygen supply. Another problem is evaporation. Approximately

14 forty-percent of the nation's water supply is lost yearly to evaporation. In the Western US, eleven billion gallons of water are evaporated daily from (Palmer, "Lifelines" 193). In Glen Canyon, water is also lost from seepage into the canyon walls. 1.2 billion cubic meters of reservoir water is lost into the canyon walls each year ("The Big One" 65-66). Since the reservoir traps so much water for electric use, the flow through the dam is the primary problem. Therefore, the reservoir is just one concern. The flow through the dam is the factor that directly contributes to the alterations of the river activity.

Water Releases The capability of Glen Canyon Dam and Lake Powell to accept highly irregular discharges, such as floods, and then to release a large controlled output of water is called flow regulation. In order to execute this operation, the reservoir must contain a large enough capacity of water (Graf 18). Since the dam operates under a strict guideline of operating procedures, the flow through the dam on a daily and yearly basis is changed regularly. Past seasonal high and low flows are now replaced by daily fluctuations. In order to maximize the efficiency of power generation, water discharge is varied throughout the day. High flows are needed for maximum power and lower flows for lesser demands. Before the dam flowsr eached a maximum of 100,000 - 200,000 cfs. Only three-percent of the time does the flow exceed 30,000 cfs, compared to eighteen-percent in the past. In addition, only ten-percent of the time have the flows been below 5,000 cfs. This is compared to sixteen-percent before the dam. Differences between the daily maximum and minimum releases range from about 12,000 - 16,000 cfs, which equals a ten-foot difference between high and low water on any specified day.

15 (U.S. Dept. of Interior. Geologic Survey. Western Region. Effects of Glen Canyon Dam on Water l). With the daily changes in flow regulation, there has also been significant changes in the downstream rapids.

Rapids Rapids are formed by the creation of debris fans. The fans consist of piles of rock fragments ( to boulder size) that have tumbled down from the canyon walls and tributaries. During heavy falls, the rock fragments break loose or are transported by the turbulent flow to a new location. Rapids form when the river charmel becomes constricted by massive amounts of debris. Spring floods that once averaged 100,000 cfs contained enough energy to clear out the debris, allowing water to msh in and transport and break-up the debris. Now, because the flows are not strong enough to move many of the heavier objects, new material is able to pile up on top of the older debris. Since the flows rarely exceed 30,000 cfs, there is not enough energy to pick up and move the majority of the debris fans. Debris fans continue to pile-up, constricting the river even further. As the river continues to clog-up, the backwater channels begin to receive heavy loads of sediment. As the backwaters increase with sih, they block the habitats of native species. (U.S. Dept. of the Interior. Office of Sec. Babbitt Signs Permanent Colorado River Protection 1-2) This snowball effect leads to problems with the sand and .

Sand and Sediment

Before the dam, the river would bring sixty-six million tons of eroded sediment to the head of the Grand Canyon each year ("The Big One" 65-66). The sand and sediment would be used for camping beaches, species , and stmctural support for archaeological sites. After the dam, the majority of the sediment became trapped in the reservoir, unable to be carried downstream. With the installation of flow regulations, the

16 altered frequency of flooding has had dramatic effects on the sandbars and beaches. It has reduced the size of sand bars and caused a reduction in the number of beaches built and cleaned-out on a yearly basis. The loss of sand and sediment means a loss of habitat space for animal species and river mnners. In the past, the river skillfully eroded away beaches and then rebuilt them thicker and wider. River mnners and wildlife had relied on these beaches to camp and seek shelter. But the reduced flows have just carried the beaches away and not rebuilt them. Polluted beaches were once replaced with clean material, but now the process is very limited (Graf 51-52). Archaeological sites were in jeopardy due to the erosion. The wearing away of the beaches supporting the canyon walls were eroding at a greater rate than the of new material. If the process continues, the walls could be undermined, potentially causing the walls to collapse (Shapard 26-30). The sediment and sand input combined with the erosive daily variations, has dismpted the cycle of deposition (U.S. Dept. of Interior. Geological Survey. Western Region. Effects of Glen Canyon Dam on Sediment 1-2). This direct influence of the sand and sediment can be seen in the vegetative communities.

Vegetation

A river environment operates in a dynamic state of equilibrium. But since a variety of water discharges are released from Glen Canyon Dam on a daily basis, an equilibrium has been hard to establish. One of the places to see this is in the vegetative communities.

The plant communities growing in and near the river and its channels are directly influenced by the water processes. Not only do they depend on river conditions for their range; they also depend on the altitude. The river and altitude help in preserving ecological diversity, landscape aesthetics, and wildlife management. Fish, birds and animals all depend on the vegetation for spawning areas, food, shelter, and protection. Thus, any activity that harms the vegetation harms the entire community. Once accommodated to

17 drastic levels of water fluctuations, vegetative populations have had to adjust to more consistent and generally higher levels of flows. In the past, the raging floods would sweep in and clear out overgrown vegetation. Because of the low levels of the water, the vegetation is able to grow thicker and fiirther down by the river channel. The management of the floods on the plants served as control measures to remove the obstmcting plants and let the water move across flood plain surfaces and through channels where they have grown. As a result, exotic plant species have been able to intmde and grow at a rapid pace. Russian Olive (Elaegnus aqustifolia) and Elm (Dyssodia sup.) are two such species (Graf 57). The floods would also bring in fresh water to channels and eddies suffering from stagnate water. If not flushed out, the stagnant water cripples the backwater habitats.

Backwaters Backwater areas are the places where water is held or pushed back by the river or current. With less water flow and floods, the delicate marshes are quickly becoming filled in and losing their energetic nutrient cycle (Wegner 1). They are becoming overgrown with riparian vegetation and stale water. Stagnant water is not flushed with newer water and sediment. Insects that feed the birds are not hatching because of the absence of agitated water (McNamee 20). The backwaters are missing the higher periodic flows that scoured the accumulated fine and vegetation. A rejuvenation process was needed to recreate a low-velocity habitat for the fish (Anderson 2). The combination of vegetative communities and backwater locale relied not only on the water levels for their survival but also on the water chemistry.

18 Water Chemistry and Temperature Water temperature, heavy metal content and salinity have altered the river in many ways. Shaphard explains that the once churning and turbulent waters were able to mix oxygen from the atmosphere into the water. Yet after the dam, less oxygen occurred and a rise in nitrogen was noted. Water temperature dropped from a maximum temperature of eighty-two degrees Fahrenheit to a maximum of fifty-four degrees Fahrenheit today, a difference of twenty-eight degrees. Although the temperature maybe a blessing for trout fisherman, the temperature is too low for the native fish species such as the Humpback Chub. Water released from the bottom of the reservoir is too cold and nutrient deficient. This differs from the water near the surface of the reservoir where it is warm and nutrient rich. The river used to mn warm and muddy, but now mns cold and clear. This would be ideal for a cold mountain stream, but that is not its locality. (Shapard 26-30) In addition to water temperature and chemistry, the dilemma of heavy metals lie concealed within the river.

Heavy Metals

Heavy metals from and milling processes are released in large amounts into the river. By traveling in the river, Graf notes they are mobilized and deposited onto the surface environment. Common heavy metals include gold, silver, vanadium, radium and uranium. Once in the river, they dissipate into solutions and can travel as particles entrained by the flow. A typical problem with heavy metals, especially mercury, is biomagnification. When organisms consume toxic chemicals, higher and higher concentrations accumulate in the succession of higher level organisms. Because the chemicals cannot be broken down or excreted from the body, they stay with the organism and are passed along, thus threatening the life of such organisms. (Graf 64) A more alarming problem associated with heavy metals is salinity.

19 Salinity Salinity is a growing problem with the ovemse of the utilization of water. When water evaporates, the material left behind is salt. Graf explains that water that is transpired by growing plants and the evaporation from and water surfaces leave's behind its dissolved minerals. This increases the concentration of materials left in the trailings. The salt can be left in the soil and then picked up by the next flood and carried along to be relocated in another area. It can also be a result of the evaporation process in reservoirs. Roughly twelve-percent of the Colorado's river flow evaporates from Lake Powell. This raises the salt levels and increases the salinity in the downstream flow. Net results mean an increased cost in the use of and a decline in agricultural productivity. Water resource costs increase because urban water must be treated to reduce the salinity content. The normal amount of salt that a human being can tolerate is 500 parts per million, (ppm). Normal conditions are about 250ppm, but have doubled since the dam.

An increase of evaporation per acre of irrigation in the Upper Basin (CO, UT, NM) has contributed an additional 1.7 tons of salt to the river. Consequently, the water that is allocated to Mexico is in such poor condition that a desalinization plant has to be constmcted. The Mexican treaty allowed for an allocation of a percentage of the river's flow. However, the water that is delivered to the Mexican government can hardly be used because it carries ten-million tons of salt per year. United States taxpayers are spending $365 million dollars to build the world's largest desalting plant to improve the lower Colorado River water. Half of the salt is a direct result of upstream water projects that divert the flows for irrigation. When the fields are flooded, salts in the soil dissolve into the water, which then mns into the river. (Graf 61-62) Mexico gets the left-over resuhs of our mismanagement.

20 Endangered Species The final call for operation change was the threat of forever losing endangered animal species. In 1973 the Endangered Species Act was signed into law. Under the law, the Secretary of Interior maintains a list of endangered species and prohibits buying, selling, or killing of those species. The law was enacted to help save and repopulate species in danger of extinction. With respect to wildlife, there are three values used to justify their existence. Esthetic value encompasses the appreciation of the wildlife for their natural beauty. Recreational value includes hunting, bird watching, photography and money. Ecological value embraces the importance of their special role in an ecosystem. The values are subjective and lead to the irony of the Colorado River system. In the river system, three native species have disappeared, two are listed as endangered, and one is a candidate for the list. The Colorado Squawfish, Bonytail Chub and Roundtail Chub have completely disappeared. The Humpback Chub and the are listed as endangered. The Flaimelmouth Sucker is a candidate for listing under the Endangered Species Act. The only two native species still in relatively abundant numbers are the Bluehead Sucker and the Speckled Dace. Reasons for the fish species decline are complex. Simple known factors include competition and predatation by non-native fish, habitat changes, and a fragmented ecosystem, all brought by the constmction and operation of Glen Canyon Dam (U.S. Dept. of Interior. Geological Survey. Western Region. Effects of Glen Canyon Dam on Fish 1 -2).

The dam has blocked nutrients in a way that damages the streams and that feed off the Colorado. The build-up of sand and vegetation has blocked the migration offish to their spawning beds. Fish need spawning grounds of gravel that are washed and cleaned by the current; stagnant water is of no use to them. The grounds need to bring in fresh oxygen to the fish eggs. The oxygen is also needed to help the larvae of

21 mayflies, stoneflies and other fish to survive. (Palmer. "Endangered Rivers" 9) Fish have had to change from the pre-dam condition of a high silt load river to a more clear, cold, and low silt environment. McNamee notes that these changes put stress on the species, which dismpts their lives. The only really good feed they receive is from the area directly below the dam. Here, nutrient rich sand is scraped from the river bottom during a flood and the vegetation is torn away from the riverbanks, providing fresh feed (McNamee 20-22).

Changes in other parts of the river have caused numerous problems for the native fish. The Colorado Squawfish, a relative of the minnow, used to grow to a length of two meters. Now they have disappeared. The Humpback Chub and Razorback Sucker rely on the formation of backwaters along the river. It is a key habitat for the fish that has suffered (McNamee 20-22). The Humpback Chub is endangered because its habitat is defined by the Colorado River; it is the only place it is found. Oddly shaped, the Chub is two pounds and can live up to thirty years. For safety it uses turbid water as cover during feeding season as well as against predatation. Lower water temperatures from the dam have significant consequences on its reproduction capability. The water in the main stream is too low for it to successfully reproduce. Today, locals claim that they rarely see the Chub in the Colorado River. This was once a fish that was so common that boaters used it regularly as food. (Cone 34-40)

One fish that has thrived in the Colorado since the dam is the . The Rainbow Trout is not a native species. It was introduced in 1964 by the Arizona Department of Game and Fish. Even though many other non-native species have been introduced through-out the years, trout make up the majority of non-native species in the Colorado River through Glen and Grand Canyons. Catfish and Carp have been present since the late 1800's. Other warm water non-native species have dominated the natives

22 since the 1950's, but after the dam their numbers declined. Trout is the only non-native post-dam species to be successful. The post-dam conditions support a highly successful Rainbow Trout fishery in the Grand Canyon below the dam. Their success is due to the clear and cold water. One positive attribute from the trout is the attraction of Bald Eagles. Bald Eagles stop in the Grand Canyon during the winter to feed on the spawning trout and fish stranded by fluctuating flows (U.S. Dept. of Interior. Geological Survey. Western Region. Effects of Glen Canyon Dam on Fish 1-2). Many fisherman have expressed concern over the controlled experiment for fear that their favorite recreational pastime would be threatened. But ironically, they showed hardly any concern over the river's disappearing native creatures.

If the controlled flood was to be carried out, a plan of action would need to be made. With the backing of the Bureau of Reclamation, a gathering of ideas became a reality.

23 CHAPTER VI

THE PLAN

A river ecosystem that once thrived in the dry desert of the Southwestern US, was reaching a critical point of permanent alteration. As mentioned before, the Glen Canyon Dam had stifled the delicate ecosystem of the Grand Canyon. If changes were not brought about soon, the balance of the river would change forever. In 1982, the Bureau of Reclamation conducted a Grand Canyon Environmental Study to review the impacts of Glen Canyon Dam operations (U.S. Public Affairs Office. Temperature Control Modification at Glen Canyon Dam 1-2). This was a very important first step in leading to the eventual experimental flood of the Grand Canyon.

During an unusually heavy flooding in the Fall of 1983, the flood alerted scientists to the possibility of regulating the riparian environment by imitating the course of nature. This sudden unexpected flood promoted scientists to analyze the effects of hydroelectric-power-plant releases into the water. The accidental flood of 1983 raised the level of Lake Powell so high that a temporary eight-foot wall was built on top of the dam and water was released as fast as possible to keep the Lake from overiapping the dam. The flood discharges were maintained for about a month with a peak discharge of almost 100,000cfs. This was comparable to the natural floods and proved to be the evidence to support the experimental flood (U.S. Dept. of Interior. Geological Survey. Post Dam Floodflows Through the Grand Canyon 1)

Scientists soon discovered that a release greater than 33,000 cfs could have a dramatic and positive affect on downstream life (McNamee 20-22). As a result, from 1900-1991, dam operators released various flows to enable scientists to test their hypothesis. The flows were tested to determine how their rate impacted the downstream

24 environment and how these flows affect the cost of hydroelectric power (U.S. Dept. of the Interior. Office of Sec. Babbitt signs Permanent Colorado River Protection 1-2). The accidental flood was not the first time major releases happened. In 1965 excess water had to be released from the reservoir due to unusually high rainfall amounts. In 1980, excess water was again released from Lake Powell to test the spillways. This would later turn beneficial because the spillways were a major factor in releasing so much water during the experiment. For one month in the years of 1984, 1985 and 1986, a flow rate of 40,000-50,000 cfs had to be maintained because Lake Powell was so full. These other major releases soon became the backbone of data for the experimental flood in 1996 (U.S. Dept. of Interior. Geological Survey. Post Dam Floodflows Through the Grand Canyon

!)• From these results, Congress passed the Grand Canyon Protection Act in October

1992. The act directed the Secretary of the Interior to "operate Glen Canyon Dam... in such a manner as to protect, mitigate adverse impacts to, and improve the values for which the Grand Canyon National Park and Grand Canyon were established" (U.S. Dept. of Interior. Office of Sec. Babbitt Signs Permanent Colorado

River Protection 1-2). For the first time, a concentrated and serious look at the dam was being taken. To further the cause. Secretary of the Interior Bmce Babbitt called for an

Environmental Impact statement to be conducted. It was the first ever to be carried out on a federal project already in operation (Wegner 1-2). Thus, it was decided to conduct the biggest living experiment to date. In March of 1996, Glen Canyon Dam would be put to the test in an experiment that would be watched around the world.

One of the main driving forces behind the experiment was the BOR Glen Canyon

Environmental Studies. The main goals of the experiment were to determine the right temperature combination to benefit the native endangered fish, while discouraging

25 non-native competitors. The US Department of Fish and Wildlife wanted to have the water drawn from different levels of the reservoir. Instead of all the water being discharged from the lower levels, they wanted the water drawn closer to the surface to ensure warmer water (U.S. Public Affairs Office. Temperature Control Modifications at Glen Canyon Dam 1-2). The idea was that a raise in water temperature would benefit the endangered species, but still keep the water cool enough to sustain the trout population. Other tentative assumptions about the experiment focused on the problem of sediment flow. Scientists predicted that the periodic high flows could be used to retain the sand in the canyon by depositing it along the river banks. They assumed that the sand immersed in the river is not completely stationary, that it is slowly being transported downstream along the river channel. They believed that the flood would just increase this process at different rates and elevations. Hydraulic energy produced from the flood would be great enough to suspend the sand and to form bars higher up on the riverbanks . The higher sandbars are desirable because they are less subject to erosion and are more useful for camping, compared to the bars formed by lower rate flows. Finally, the increased water amounts should be powerful enough to clear out debris fans and to reshape many of the rapids. (Anderson, Graf, Marzolf 1-4) With their preliminary theories, the BOR set out to perform the experiment.

26 CHAPTER VII

THE EXPERIMENT

With eager anticipation, the flood gates of Glen Canyon Dam were opened. People watched with amazement as 117 billion gallons of water were released from Lake Powell into the Colorado River. For a brief time, the Colorado River would mn wild again with man's blessing.

The experiment was being conducted to test the dam's operations procedures and to see if a change in dam releases would benefit the Colorado river ecosystem. Scientists had become alarmed when the downstream river ecosystem began to suffer under low and methodical water flows. It was now time to test the river and to begin a detailed study on why spring floods are needed to regulate plant and aquatic species that depend on the river system for their existence.

The actual experiment began on March 22, 1996, four days before the massive water releases. Discharges from the dam were lowered and held at 8,000 cfs, 4,000 cfs below the normal dam release. The drop in discharge was required so pre-flood pictures of the river could be taken. Then, on March 26, 1996 the gates were opened and the flow was raised to 45,000 cfs. The dam operators opened four eight-foot wide overflow tubes to raise the flood to its peak release level. For seven days the release was kept steady at 45,000 cfs. On the eighth day, the flow was changed back to 8,000 cfs to assess the post-flood conditions. By mid-April the flows were increased back to the normal flow of around 12,000 cfs. In all, 117 billion gallons of water were drained from Lake Powell. The fastest flow rate was 45,000 cfs compared to just 10,000 cfs under normal operating conditions (McNamee 20-22). In order to measure and observe the flood, several observing areas and data collection techniques were used throughout the experiment. In

27 addition, physical and chemical measurements of the water in Lake Powell would be made near the dam on a daily basis. The purpose would be to help locate and define the area from which the controlled flood water was drawn (Anderson, Graf, Marzolf 1-4).

To keep the scientists and the general public informed on up-to date information, satellite telemetry was used. Because of this, real-time stream-flow data would be made available on the Intemet. Four stream-flow gauge stations along the river below the dam were equipped with satellite telemetry. Through this, means anyone who wanted to observe the flood in action could click in and the events of the day would be available for viewing (Anderson 1-2). The river stage data would be measured at about forty sites. The stage data would be used to test the methods of predicting the arrival of the peak waves of the flood. Discharge would be monitored at five main-stream and sites.

Maps were also used to understand the flood. Historical surveys were consulted to review pre-dam conditions and images. Secondly, global positioning system was used to map the regions in question and to provide future data sets. A baseline was used by pin-pointing exact locations of dozens of geographic points. These points would later be used for fiirther mapping and image comparisons. Inflatable boats carried tools to map the river bottom's contours.(Cone 34-40) All this would serve as a valuable information base for further reference.

Dye was injected into the river on March 27, 1996, to measure the velocity of the flood flow. 2,200 pounds of non-toxic dye was injected into the Colorado river. Measurements taken on how fast the dye traveled downstream and mixed with the water would aid in the generation of computer models of the river and the flood. The dye, Rhodamine WT, was mixed with 400 gallons of water and then sprayed into the river with gas powered pumps and fire hoses at one mile from . Total time to inject was twenty

28 minutes. The velocity of the river was measured by its timed arrival at pre-determined distances downstream. (Anderson 1-3)

Measurement of the velocity would allow for the estimation of basic river-channel characteristics needed to extend methods for predicting flow and sediment transport in floods. Several eddies would be intensely monitored to document the flow patterns and accumulation of sand. This would help explain the critical role of eddies in trapping and storing sand along river banks. To measure transport of sediment, approximately 100 cross sections of river channel would be measured before and after the flood to determine changes in sand storage. On selected cross sections, measurements would be done to determine the rate of change of transportation. Collections of suspended sediments would be taken to check for concentration and particle size at several main-stream sites. (Anderson, Graf, Marzolf 1-3)

When the initial seven day experiment was over, the beginning of data study began. Scientists will scmtinize the data, graphs, and measurements to study how the experimental flood changed the river.

29 CHAPTER VIll

RESULTS

From a bold innovative experiment came the critical data to support the need to protect the critical ecosystem of the Colorado River through the Grand Canyon. After a seven day release of elevated discharge rates, the data were analyzed and a conclusion was made. The results were able to support the theory that increased controlled releases of water from a dam to simulate spring floods can have many positive effects on downstream activity. Key results were noted in the physical and biological environments.

Among the physical system changes were reconstmction of sandbars and camping beaches, sediment transport, rapids, and backwater habitats. (The U.S. Dept. of Interior's report Glen Canyon Environmental Studies presents an authoritative account of these changes.)

Sandbars and Sediment Transportation

A study of bathymetric surveys revealed that the sandbars had gained a significant amount of sand during the flood. On average, the volumes increased fifty-three-percent.

The flood waters raised the sand high enough on the banks to avoid daily erosion. Even though the sand was deposited at higher sites, the overall area of the sandbars increased only slightly. The main eroding process of the flood occurs at the beginning when the sediment-transport capacity is rising. The massive scouring action occurred from unexplained rapid changes in eddy circulation. Sand was scoured from the steepest part of the channel and eddies to be deposited and built on the channel margins. The supply of sand and channel geometry of a particular location determines how sand storage occurs at that particular location. A net deposition of 0.5 to 2 meters of sand at eddy reattachment

30 points was the average. Generally,the middle of the eddies were the places that were scoured (U.S. Dept. of Interior. Office of Sec. Glen Canyon Environmental Studies.

Floods in the Grand Canyon 1)

Rapids The two largest rapids in the Grand Canyon, Lava Falls and Crystal Rapids, had significant changes. The biggest changes were in the movement of debris fans. Before the flood, the was raised by the deposition of debris flows, thus constricting navigation. After the flood, the constrictions widened anywhere from thirty-four-percent to forty-two-percent, and the aggregated areas (debris fans) were reduced by twenty-three-percent. At Lava Falls, the reworking of the debris fans made the left side mn less dangerous, but steeper by rearranging the debris. Overall, out of sixteen studies of debris fans, eight decreased in size by ten-percent or more, and four of them had 1,900 cubic meters of debris eroded away. The overall velocities in all the rapids decreased from the clearing, making the navigation through them safer and easier. It was decided that the debris fans would be changed and rebuilt about every five years after a if the discharge rates were similar to the ones in the experiment. Altogether, the debris fans located where the stream power is the highest are the ones that had greater change compared to debris fans adjacent to riffles. (U.S. Dept. of Interior. Office of Sec. Glen Canyon Environmental Studies. Floods in the Grand Canyon 2).

Camping Beaches

River mnners would commonly use the large riverside deposits located above the

area of daily river fluctuations as campsites during their trips. As a result of the flood, fifty-percent of the campsites increased in size, thirty-nine-percent remained the same size and only twelve-percent decreased in size. The ones that did increase in size grew by an

31 average of fifty-seven-percent. In addition, the flood created eighty-two new campsites and destroyed only three previously existing campsites. The post-dam deposits of the sites are smaller in area, but reach to a greater elevation and are much thicker and extensive than previously. (U.S. Dept. of Interior. Office of Sec. Glen Canyon Environmental Studies. Floods in the Grand Canyon 2).

Backwater Habitats

Due to changes in shape and extent of reattachment sandbars, new backwater habitats were created. Because backwaters are dependent on the degree to which reattachment bars are created, the flood benefited them greatly. The amount of deposition in the channels and the volume of water that flows though a river system define the health of the backwaters. The flood was able to scour out retum flow charmels and rejuvenate the backwater habitats. Fresh water and sand from the main channel was brought in and the number of backwater habitats increased by twenty-percent immediately after the flood. (U.S. Dept. of Interior. Office of Sec. Glen Canyon Environmental Studies. Floods in the Grand Canyon 3).

Within the biological system of the controlled flood, changes were noted in several areas. The geochemistry of the water grew healthier. Fisheries and endangered species saw several benefits. The riparian vegetation and resources were reduced as planned. Finally cultural resources were protected.

Geochemistry

Biochemical rejuvenation of the river ecosystem resulted from the flooding. Burial and accelerated decomposition of organic matter occurred by the burial of living and detrital organic material under 0.2 to 0.95 meters of sand. Measured sites revealed ground

32 water had an increase in ammonium and non-purgeable organic carbon with decreases in dissolved oxygen. This was evident from the increasing rates of microbial respiration in the beaches and cycling of dissolved carbon from the beaches into the mainstream. (U.S. Dept. of Interior. Office of Sec. Glen Canyon Environmental Studies. Floods in the Grand Canyon 3).

Fisheries During the controlled flood, no significant decrease in fish density of non-native fishes occurred because they found shelter beneath submerged riparian vegetation. The juvenile Humpback Chub remained along the shorelines. The Speckled Dace relocated from rifflest o the debris fans, and the feathered minnows moved from the tributaries to the backwaters. Radiotelemetry and netting studies indicated that many of the larger native species elected during the flood to stay in low velocity areas in recirculation zones below large debris fans. As for the trout species, there have yet to be any negative impacts noted. Their distribution, condition, density and health have remained constant. It is still yet to be know if fiirther floodso f warmer water will help repopulate the endangered native fish species. (U.S. Dept. of Interior. Office of Sec. Glen Canyon Environmental Studies. Floods in the Grand Canyon 3).

Riparian Vegetation and Resources The overall hypothesis of scientists concerning the riparianvegetatio n was correct. Many of the herbaceous species, especially the annuals, were significantly reduced in the flooded areas. The perennial herbaceous species have since recovered after the flood. An overall positive effect on the woody perennial species was notable. Except for a small amount of , they are flourishing.Th e overgrown and dense vegetation was

33 cleared from the sandbars, and the growth near the water levels were also cleared away. (U.S. Dept. of Interior. Office of Sec. Glen Canyon Environmental Studies. Floods in the Grand-Canyon 3).

Cultural Resources After completion of the dam, many cuhural sites were threatened by the undercutting of the beaches supporting them. Following the flood,i t was found that no erosion had occurred, but also no great amounts of sand and sediment were deposited either. This is believed to be so because of a lack of sediment near many of the sites. When sediment was deposited, it was located in the mouths of the deep cut by the intermittent stream. (U.S. Dept. of Interior. Office of Sec. Glen Canyon Environmental Studies. Floods in the Grand Canyon 4).

34 CHAPTER IX

CONCLUSIONS

In conclusion, it was determined that the controlled flood was essential to learn the relationship between aquatic organisms and their habitat. Organisms within a river ecosystem have come to rely on periodic disturbances in order to sustain survival. Without water fluctuations, such as floods, their habitats suffer. By researching species composition, diversity, dynamics and stability of Colorado River ecosystem, scientists have concluded that periodic floods are an essential element.

The controlled flood has initiated a complex sequence of adjustments. Backwater habitat are rejuvenated, beaches are in greater quantity and quality, and water temperatures have risen. Overall, the hypothesis was proved that a river ecosystem is altered by dams and can be restored by periodic controlled floods. Scientists continue to analyze their data and monitor critical areas. At the present moment, the research is still considered short term and thus no immediate decisions will be made for dam operations. The long term research and studies resulting from the experimental flood will continue to be monitored to ensure that a valid decision will be made. This is only the start in the change of dam operations. Until more research on releases can be done, the full value of a flood will not be known.

35 BIBLIOGRAPHY

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Anderson, Mark T. "Press Release: USGS to use Dye in Study of Controlled Flood in the (jrand Canyon; Real-Time Data from Flood will be Available on the Intemet." Water Resources Division, USGS 21 Mar 1996: 1-4. http://www.daztcn.wr.usgs.goy/floorpr.html

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36 Ribokas, Bob. "The Geology of the Grand Canyon." Grand Canyon Explorer . Sept. 1996: 1-10. http://www.daztcn.wr.goy.gce/geologygc.html

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37 United States. Department of the Interior. Geological Survey, Western Region Coastal and Marine Geology. Effects of Glen Canyon Dam on Sediment in the Grand Cany£ML8 Apr 1996:1-2. http://walms.wr.usgs.gov/docs/projects/grandcan/sedeffects.htnil

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