Return to Case Digest Archives
Archive of Prominent Section 106 Cases:
Fall 2000


Hoover Dam Bypass

U.S. Courthouse
(San Diego)

Yosemite Valley Plan

Letterman Project
(San Francisco)

Long Beach Naval Station

District of Columbia:
WWII Memorial

Fort Benning

Industrial Canal Lock
(New Orleans)

Stillwater Lift Bridge

Philadelphia Naval Hospital

South Dakota:
Francis Case Reservoir

Chancellorsville Battlefield

Return to Archive of Prominent Section 106 Cases

Arizona-Nevada: Construction of
Hoover Dam Bypass

Agency: Federal Highway Administration

Criteria for Council Involvement:

  • The proximity of the proposed bypass around Hoover Dam presents high potential for adverse effects to this National Historic and Engineering Landmark (Criterion 1).

  • The project alternatives lie within an area identified by several Indian tribes as containing properties of tribal religious and cultural significance (Criterion 4).

Recent Developments

In August 2000, following further consultation with tribal elders and the completion of ethnographic studies, the Federal Highway Administration (FHWA) convened a meeting to discuss the potential National Register eligibility of several traditional cultural places which may be affected by the proposed highway bypass around Hoover Dam. Representatives of the Council, affected tribes, and other consulting parties attended.

The meeting led to a recommendation that FHWA determine the hot springs of Gold Strike Canyon and an area around Sugarloaf Mountain to be eligible. FHWA will coordinate closely with the tribal working group and the State Historic Preservation Officers (SHPOs) of Arizona and Nevada to finalize the determinations of eligibility and proceed with development of a Programmatic Agreement.


The Central Federal Lands Division of FHWA is the lead Federal agency for development of a proposed bypass around Hoover Dam. Currently, traffic over the Colorado River between Arizona and Nevada is carried across the dam via U.S. Highway 93. Increased congestion and conflicts between through traffic and dam visitors have sparked the need for a second river crossing. (For more information on the project, visit

The Bureau of Reclamation initially began environmental review for the project in 1989 but withdrew in 1993. FHWA took over the project and published a Draft Environmental Impact Statement (DEIS) in 1998. Following public meetings, FHWA selected the “Sugarloaf Alternative” as the preferred alignment. This alternative calls for a new 2,000-foot bridge to be located approximately 1,000 feet downstream of the dam and 230 feet above its crest.

Hoover Dam

Hoover Dam
(Photographer: Bureau of Reclamation, Lower Colorado Region)

Dedicated in 1935, Hoover Dam is among the largest and earliest of the Bureau of Reclamation’s massive multi-purpose dams. Distinguished by its size, its Art Deco detailing, and its engineering significance, the dam has had a critical impact on the development of the Southwest. Construction of the “Sugarloaf Alternative” would introduce a significant visual intrusion into the dam’s setting, which remains unchanged in many respects from the 1930s. Several archeological sites along the Arizona approach also require further investigation.

When the Council was notified of the project in September 1999, the only identified effects to historic properties were visual impacts to the dam. Limited ethnographic studies had been conducted prior to publication of the DEIS, so additional coordination with Indian tribes was necessary to meet the provisions of the Council’s revised regulations. Over the past year, FHWA has made great strides toward rectifying this problem.

FHWA convened a meeting in January 2000, inviting 17 tribes to discuss properties of cultural or religious importance that might lie within the project’s area of potential effect. Attending tribes noted that FHWA’s preferred alternative would significantly impact Sugarloaf Mountain, a tribal sacred site. Another alternative that avoids visual impacts to the dam would nevertheless have significant impacts on Gold Strike Canyon, a canyon downstream from the dam that contains hot springs of cultural significance to several of the tribes.

The alternative generally preferred by the tribes lies upstream of the dam across Lake Mead. However, this alternative poses a potential safety risk to this major water supply, should there be a hazardous waste spill on the bridge.

In February, FHWA met with representatives of the Council and the Arizona and Nevada SHPOs. It was agreed that the next step for FHWA is to make formal findings of effect for each of the three alternatives, following completion of efforts to identify historic properties in the area of potential effect. To advance the identification effort, a core working group of tribal representatives was identified to act as points of contact representing the Indian tribes with major interest in the area.

Policy Highlights

This project demonstrates the importance of adequate consultation with Indian tribes during Section 106 review to ensure that historic properties of concern to tribes off tribal lands are identified and addressed. It also highlights the challenges posed in attempting to balance consideration of project impacts to historic buildings and structures with impacts to properties of religious and cultural significance.

Staff contact: MaryAnn Naber

June 2000 report on this case

Return to top of page

ACHP home page Working with Section 106

We welcome your feedback