Constructed 16 miles upstream from the Grand Canyon National Park, the Glen Canyon Dam was built in 1963 - at a time when there was no legislation to protect the country's natural resources. The Glen Canyon Dam stores and releases water from Lake Powell, with its capacity of about 27 million acre-feet of water. Built to provide power for Western states, the Glen Canyon Dam has changed forever the fragile ecosystem of the 286-mile Colorado River, which stretches through the majestic Grand Canyon.
      Thirty-two years after the dam's construction, scientists and researchers involved in the Glen Canyon Environmental Studies project are researching and monitoring the long-term effects of the Glen Canyon Dam on the environment, native vegetation and wildlife. The subject area for the project is the Colorado River corridor - which runs from the Glen Canyon Dam through the Grand Canyon to Lake Mead - and includes resources located in the river channel and along a narrow band of adjacent land.
      Scientists and researchers are carefully monitoring the environmental impact of the dam, studying how changes in water level, rate of flow and temperature affect wildlife and archaeological sites. Participants in the project employ a range of technology instruments - from electronic data collectors typically used by commercial surveyors, to PCs loaded with software that accurately maps the geographical contours of the land.
      One software package in particular - TERRAMODEL, 3D land-modeling software from Plus 3 Software Inc. of Atlanta - is being used to create highly contoured maps of the riverbed and shoreline. The maps are used to identify changes in vegetation growth along the Colorado River, to illustrate the differing water temperatures of the river's channels, to mark sediment shifts, and to pinpoint spawning areas for particular species of fish.
      Methods of data-collection for the map-making include dependence on the satellite-based Global Positioning System, land-based and aerial photogrammetry, as well as Sokkia (Lietz) Total Stations and TDS and Sokkia data collectors. Another software program, Hypack from Coastal Oceanographics, is used to generate x,y and z values from just underneath the water's surface to the river's floor. These numbers are then fed into the TERRAMODEL system and are used to generate river channel-mapping.
      Years of monitoring and recording changes in the Colorado River have been used to develop an Environmental Impact Statement that identifies the changes to the ecosystem that have taken place since the dam's construction and potential changes in dam operations. Mandated by the U.S. Department of the Interior in 1989 and fueled by the Grand Canyon Protection Act of 1992, the Environmental Impact Statement was released this past spring. The statement also offers some alternatives for reducing further damage. The Environmental Impact Statement will be used by decision-makers in the U.S. Bureau of Reclamation and the Department of the Interior to guide the dam's future water flow.
      The hope is that future power needs generated by the Glen Canyon Dam will yield to environmental considerations. Scientists and researchers involved in the project agree it is unlikely that the Colorado River ecosystem can ever return to pre-dam conditions. However, the dam's operation can be modified to significantly reduce the current degradation of the geography and indigenous wildlife and offer unique opportunities for restoration of critical resources and ecosystem processes.

The Long-Term Effects of Man's Intervention
In the beginning, it seemed ironic that something as beautiful and as deeply rooted in Mother Nature as the Colorado River could be used to serve the needs of man. Lake Powell, the artificial reservoir that resulted from the dam's construction, is today a popular recreational site. Electricity is generated by releasing water from the Lake Powell reservoir, through the Glen Canyon Dam's turbines into the Colorado River. This process represents a relatively inexpensive power source that is utilized by five Western states.
      According to Chris Brod, a licensed surveyor who is also a senior programmer and systems analyst with the Glen Canyon Environmental Studies project, it is the rapid release of water through the dam's turbines that is the most detrimental to the river's ecosystem. Although the release of water is necessary to generate power, it causes water levels in the Colorado River to fluctuate dramatically.
      "We've seen changes in water levels as much as 10 feet in one day," says Brod. "This contributes to the erosion factor on the canyon riverbed. In addition, the dam traps sediments that used to flow freely down the river so the shorelines aren't being replenished as they have been naturally for thousands of years."
      Prior to the dam, the Colorado River did endure its share of flooding. In fact, flooding during the spring was common. But with natural flooding, the waters brought with them the valuable sediments to replenish the riverbed and shoreline. In essence, even though the floods were destructive, they nurtured as well. Now, however, the rapid release of water is a man-made occurrence, and the clear water brings with it none of the sediments, which are now trapped at the bottom of Lake Powell. This means that the rapid release of water from the dam can have only one result - erosion.
      When the water released by the Glen Canyon Dam reaches its highest point, it is wearing away at many important archaeological sites along the canyon's red-rock walls. Some of the sites are prehistoric, while others include historic sites of Native Americans.
      Water being released from the dam's turbines is perennially cold - a significant factor, since the average water temperature in the Colorado River downstream from the dam has dropped by some 28 degrees. Previously, the water was seasonally warm, but it now averages only around 46 degrees Fahrenheit year-round. The cold water is being drawn from the coldest depths of Lake Powell, 230 feet below the lake's surface.
      This change in water temperature has helped Rainbow Trout - which were introduced into the area soon after the dam's completion - to thrive. Many native species of fish are unable to spawn in such cold waters. The native Humpback Chub is now listed as a federally protected endangered species, while three other species of native fish - the Colorado River Squawfish, the Bonytailed Chub and the Razorback Sucker - are already eliminated from their historic habitats.

Working To Preserve The Ecosystem
Scientists and researchers involved in the Glen Canyon Environmental Studies set out for days, sometimes weeks, into the wilderness, where they monitor the changes taking place in and along the Colorado River. While they carry the traditional supplies one might expect for living and working outdoors - inflatable rafts, rugged clothing, camping equipment and food rations - it is just as likely that their backpacks will contain a laptop PC as a pocketknife or compass.
      The teams conducting research along the Colorado River take with them at least four to five laptop PCs, usually 486/66 computers with color screens. According to Brod, the computers are taken into the field to immediately download information gathered from the data collectors and other equipment.
      "We work in a rough, often hazardous environment - not only to people, but to our equipment, as well," says Brod. "We have had equipment damaged in a raft that got hung up on the rocks. For this reason, as soon as we collect data, we try to archive it by downloading it to a computer and then putting it on a floppy as a back-up. It's too expensive to have to go out and repeat the data-gathering process, in the event that a piece of equipment gets damaged and the data is corrupted."
      More than 150 scientific projects have been conducted in the Grand Canyon since the Glen Canyon Environmental Studies originated 12 years ago, involving literally hundreds of researchers. Brod has worked with a number of the research teams studying the Colorado River. In particular, he has worked with two groups of researchers - one studying changes in water temperature in the Colorado River; and another studying shifts in the range of vegetation growing along the riverbank. By early May, Brod had spent a total of 25 days in 1995 on outdoor excursions into the wilderness areas that run along the Colorado. In total, he has spent nearly five years with the Glen Canyon Environmental Studies project.
      "In order to more fully understand the dam's effects, we've been required to carefully map and georeference the areas and resources in and along the Colorado River," says Brod. "Although we use traditional surveying instruments, we're also using computer-based modeling software to create highly accurate contour maps. The range of studies are incredibly comprehensive and on-going, which means that we're dealing with extremely huge databases of information that can't be realistically looked at without the use of computers."
      For instance, as part of the project to monitor and report on water temperature changes at remote sites along the Colorado River, the research team is required to take temperature readings using electronic equipment designed by Ryan Instruments and Campbell Scientific. The research team starts by developing a grid of the river that includes a range of positions and geographic points. The temperature grid is designed using software that Brod wrote himself. Hypack, the data collection software used to gather data from underneath the water's surface, is hooked to a depth sounder that actually travels underwater and sends back data to a computer on the boat. These values - horizontal, location and elevation are sent from a survey instrument on shore to Hypack via radio modem - and are then fed as ASCII files into the TERRAMODEL land-modeling software.
     TERRAMODEL creates a realistic and highly accurate 3D map of the river corridor, including the riverbed and shoreline. The maps not only indicate water depth but the temperature variations as well. The maps are used by aquatic biologists working on the project to monitor the habitats and available use areas of the endangered fish.
      Brod says the use of 3D modeling software lets him plot an accurate map within a few hours, where previously it might have taken a week to do the same task by hand. At times, Brod has been known to generate the maps with TERRAMODEL on the laptops carried into the field, using the data collected by the surveying equipment to immediately create maps instead of waiting to return to the computer workstation in his office.
      "My personal preference when doing topography in the field is to immediately download the data and use it to generate a map," he says, adding that the procedure gives him the peace of mind that the data collected was both accurate and comprehensive. "It costs too much to have to go back and repeat the process if you wait until you get home to find out that you didn't do things right. Also, our job is to report changes - in water temperatures, water elevations - and other factors that aren't constant. If you miss your chance to collect the data at a certain time then that chance is gone forever. We're not dealing with a dynamic environment and TERRAMODEL helps us capture the ever-changing system."
      Brod believes the modeling done with TERRAMODEL as part of the studies has not previously been accomplished on the same magnitude with any other water system as large or as complex as the winding Colorado River. "Our research determines how the river's ecosystem has changed since the dam was first constructed," he says. "It's a rewarding experience to work with such a knowledgeable and dedicated group as the researchers and scientists who have been involved with the Glen Canyon Environmental Studies. Some of the brightest people I've ever come into contact with are working on this project."
      Of course, the release of the Environmental Impact Study has no definitive impact over the eventual fate of the Colorado River ecosystem. That will be left up to legislators and the public who will make the ultimate decisions. One can only hope that lawmakers will learn from the past and look beyond the dam's traditional value as a cheap power source.
      Many researchers believe that the dam can continue to be operational without further degradation of the ecosystem. To do this however, it will be necessary to put certain measures into place. The Studies' Environmental Impact Statement suggests a number of alternatives that would allow the dam to operate without further damage to the river and surrounding areas. Among these alternatives are proposed changes in the maximum and minimum flows, changing the river flows below the dam (also known as discharges or releases), and a number of variations on dam operations that range from unrestricted fluctuations to steady flows.
      Agencies involved in the development of the Environmental Impact Statement for the Glen Canyon Dam are the U.S. Bureau of Reclamation (Department of the Interior), the Bureau of Indian Affairs, National Park Service, U.S. Fish and Wildlife Service, Western Area Power Administration, Arizona Game and Fish Department, and the Hopi Tribe, Hualapai Tribe, Navajo Nation, San Juan Southern Paiute Tribe, Southern Paiute Consortium and Zuni Pueblo.
      A summary of the Environmental Impact Statement is available through the Bureau of Reclamation; 125 South State Street, Room 6107; Salt Lake City, Utah 84138-1102; 801/524-5479 (phone).
      Additional information on the scientific studies in the Grand Canyon can be obtained by calling the GCES office at 520-556-7363 or writing to P.O. Box 22459, Flagstaff, AZ 86002-2459.

About the Author:
Derrick Darby is the founder and president of Plus III Software Inc. in Atlanta, Ga. He may be reached at 404-396-0700.

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