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Archive of Prominent Section 106 Cases:
June 2000


Criteria for

Hoover Dam Bypass

U.S. Courthouse
(San Diego)

Geothermal Developments
(Modoc & Klamath National Forests)

District of Columbia:
General Post Office

South Lawrence Trafficway

Industrial Canal Lock
(New Orleans)

Stillwater Lift Bridge

U.S. Courthouse

New York:
Hudson River Park
(New York City)

South Dakota:
Francis Case Reservoir

South Dakota:
Federal Lands along Missouri River

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Archive of Prominent Section 106 Cases:
June 2000

Arizona-Nevada: Construction of
Hoover Dam Bypass

(Latest update)

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, including the Paiute, Ft. Mojave, and Hualapai, as containing properties of tribal religious and cultural significance (Criterion 4).

Recent Developments

In March, Council staff attended a second tribal consultation meeting convened by the Federal Highway Administration (FHWA) to explore the potential impact of a proposed highway bypass around Hoover Dam on traditional cultural properties. A core working group was identified to act as points of contact representing the Indian tribes with major interest in the area.

Primary places for additional site visits were identified, a plan for further consultation was developed, and the tribal role in any Section 106 agreement was clarified. Further coordination with tribal elders and ethnographic studies are underway, the results of which will be reported at a scheduled quarterly meeting.


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

Hoover Dam

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

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

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 is 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. Only 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. With the appointment of a new project director last summer, FHWA has made great strides toward rectifying this problem.

FHWA convened a meeting in January 2000, inviting 17 tribes to discuss the issue of properties of cultural or religious importance that might lie within the project’s area of potential effect. Tribes in attendance noted that FHWA’s preferred alternative would have significant impacts on the tribal sacred site from which its name derives: Sugarloaf Mountain.

Another alternative that avoids visual impacts to the dam would nevertheless have significant impacts on Gold Strike Canyon, a canyon downstream from the dam containing 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 risk to the safety of 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 State Historic Preservation Offices of Arizona and Nevada. 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.

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

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