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Glen Canyon Dam Long-Term Experimental and Management Plan EIS
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Glen Canyon Dam Long-Term Experimental and Management Plan EIS


What Is in the LTEMP FEIS?

The LTEMP FEIS evaluates the impacts of a long-term experimental and management plan for operations of Glen Canyon Dam on resources in and along the Colorado River.

The LTEMP FEIS analyzes the potential environmental impacts of alternative operating protocols and other management actions to protect downstream resources for future generations, conserve species listed under the Endangered Species Act, avoid or mitigate impacts on National Register of Historic Places (NRHP)-eligible properties, and protect the interests of American Indian Tribes, while meeting obligations for water delivery and the generation of hydroelectric power.

What is the geographic scope of the analysis in the FEIS?

The geographic scope of the LTEMP FEIS analysis is the area affected by Glen Canyon Dam operations and other components of the LTEMP.

In general, the region examined in this FEIS includes the area potentially affected by implementation of the LTEMP (normal and experimental operations of Glen Canyon Dam and non-flow actions). This area includes Lake Powell, Glen Canyon Dam, and the river downstream to Lake Mead. More specifically, the scope primarily includes the Colorado River Ecosystem, which includes the Colorado River mainstream corridor and interacting resources in associated riparian and terrace zones, located primarily from the forebay of Glen Canyon Dam to the western boundary of Grand Canyon National Park (GCNP). It includes the area where dam operations impact physical, biological, recreational, cultural, and other resources. Portions of Glen Canyon National Recreation Area (GCNRA), GCNP, and Lake Mead National Recreation Area (LMNRA) are included within this area. For certain resources, such as socioeconomics, air quality, and hydropower, the affected region is larger and includes areas potentially affected by indirect impacts of the LTEMP. The potentially affected regions for these resources are specifically identified in Chapters 3 and 4 of the FEIS.

Generalized Locations of Glen Canyon Dam, Lake Powell, the Colorado River between Lake Powell and Lake Mead, and Adjacent Landsclick to view larger image
Generalized Locations of Glen Canyon Dam, Lake Powell, the Colorado River between Lake Powell and Lake Mead, and Adjacent Lands (This map is for illustrative purposes only, not for jurisdictional determinations; potential area of effects varies by resource and is addressed in Chapters 3 and 4 of the FEIS.)

What alternatives were analyzed in the LTEMP FEIS?

The FEIS assesses the potential environmental effects of seven alternatives: the No-Action Alternative (Alternative A) and six action alternatives (Alternatives B, C, D, E, F, and G). These alternatives are described in the Notice of Availability (NOA) and the Description of Alternatives (Chapter 2) in the FEIS.

What impacts and issues were addressed in the LTEMP FEIS?

The LTEMP FEIS analyzes impacts on those resources that could be affected by operations of Glen Canyon Dam and other components of the LTEMP.

Direct, indirect, and cumulative impacts of the effects of the proposed action, in combination with the effects of past, present, and reasonably foreseeable future projects, were analyzed in the LTEMP EIS for the following impact topics:

  • Water resources, including annual, monthly, and hourly patterns of releases, water temperature, and water quality;
  • Sediment resources, including sand and sandbars within the active river channel, and sand that accumulates in the Colorado River delta of Lake Mead;
  • Natural processes that support ecological systems within the Colorado River Ecosystem;
  • Aquatic ecology, including aquatic food base for fishes, nonnative fishes (warmwater, coolwater, and trout), native fishes (including the endangered humpback chub and razorback sucker), and aquatic parasites;
  • Vegetation, including Old High Water Zone vegetation, New High Water Zone vegetation, wetlands, and special status plant species;
  • Wildlife, including terrestrial invertebrates, amphibians and reptiles, birds, mammals, and special status wildlife species;
  • Cultural resources, including archeological resources, historic and prehistoric structures, cultural landscapes, traditional cultural properties, and ethnographic resources important to American Indian Tribes;
  • Tribal resources, including vegetation, wildlife, fish, and wetlands, water rights, traditional cultural places, traditional knowledge, and continued access to important resources within Glen and Grand Canyons;
  • Visual resources in GCNRA, GCNP, and LMNRA;
  • Recreation, visitor use, and experience as related to fishing, boating, and camping activities in the Colorado River and on Lakes Powell and Mead;
  • Wilderness and visitor wilderness experience;
  • Hydropower, including the amount and value of hydropower generation at Glen Canyon Dam, marketable electrical capacity, capital and operating costs, and rate impacts;
  • Socioeconomics, including recreational use values, nonuse economic value, employment and income, and environmental justice;
  • Air quality effects related to changes in Glen Canyon Dam operations, including air emissions; and
  • Climate change, including the effects of Glen Canyon operations on greenhouse gas emissions and the effects of climate change on future impacts of Glen Canyon Dam operations.