The Effects of Glen Canyon Dam on the Colorado River
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THE EFFECTS OF GLEN CANYON DAM ON THE COLORADO RIVER. 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! TABLE OF CONTENTS ACKNOWLEDGMENTS ii CHAPTER I. INTRODUCTION 1 II. HISTORY OF THE DAM 4 III. LIFE BEFORE THE DAM 7 IV. FORMATION OF THE GRAND CANYON 9 V. LIFE AFTER THE DAM 14 Lake Powell 14 Water Releases 15 Rapids 16 Sand and Sediment 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 Habitats 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 Colorado River. Since the 1960's Glen Canyon 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 river ecosystem. 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 Glen Canyon Dam management, proposed an idea. They suggested that a controlled flood be released from the dam to simulate the natural spring floods 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 government 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 John Wesley Powell set off on the last great scientific expedition of the continental United States. 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 waters were traveling down stream 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 irrigation 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, Utah and New Mexico, shared the water supply with the lower basin of Arizona, Nevada and California. 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 technology 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 canyons and scores of tributaries 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 dams represent a change to life on immediate downstream river systems. Their presence on rivers has caused a rippling affect, altering the life of the community located beneath. Rapids, stream vegetation and valley landscapes 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 reservoir in the United States came into existence. Lake Powell. 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 concrete. The crest width is twenty-five feet, while the base width is three-hundred feet. The foundation geology consists of Navajo 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.