Public Safety of Reclamation Low-Head Dams

Project ID: 1799
Principal Investigator: Connie Svoboda
Research Topic: Public and Employee Safety
Funded Fiscal Years: 2016
Keywords: None

Research Question

Are there public safety concerns at low-head Reclamation dams that should be addressed? Can existing low-head
dams be retrofitted to improve public safety? Can new structures be designed to minimize public safety concerns?
Dam safety has been in the forefront for the last four decades since the failure of several large dams in the 1970s.
Forty nine states and all federal agencies with dam oversight responsibility have established dam safety programs
to regulate the design, construction, operation, inspection, and maintenance of dams (Tschantz and Wright,
2011). Reclamation has its own Dam Safety Program created in 1978 under the Reclamation Safety of Dams Act.
There is, however, little oversight of smaller structures because they will not cause loss of life or property if the
dam fails or they are exempted because they fall below a certain height or storage capacity (FEMA, 2004).
Reclamation's Dam Safety Program oversees high and significant hazard dams, so many low-head dams fall
outside of their program. High and significant hazard classification relates to the failure of the dam rather than
the hydraulic conditions that the dam produces. Dams or other structures that do not fall under the high and
significant hazard designation may still create dangerous currents, hydraulic forces, and other hazardous
conditions to someone trapped downstream of the structure. A submerged hydraulic jump occurs when the
tailwater depth exceeds the sequent depth of the hydraulic jump causing strong rotational currents toward the
dam face. Hydraulic structures that produce this type of flow condition have been termed "drowning machines".

Need and Benefit

The safety of low-head dams has not been given as much consideration as the safety of high-head dams.
Although breaching or failure may not cause loss of life or extensive property damage downstream, low-head
dams can cause significant dangers to recreationalists because of localized hydraulic conditions.
Tschantz (2014) shows how the number of dam-related fatalities caused by dam failures has decreased from
1960 to 2014 while the number of fatalities caused by low-head dams has increased over the same time period.
Kayakers, swimmers, boaters, anglers, and other recreationalists are at particular risk. Public awareness, signage,
buoys, and portage opportunities can minimize risk, but dangers from hydraulic forces remain. Tschantz (2014)
states "Hydraulic engineers are aware of the forces created by moving water and have a professional responsibility
to design safe structures to control and contain these forces."
Reclamation has a number of existing low-head structures in its inventory (e.g. Huntley Irrigation Project
Diversion Dam on the Yellowstone River and Power Canal Diversion Dam upstream of Roosevelt Dam, Arizona)
that do not even meet the criteria for a low-hazard dam based on height or impoundment volume. Reclamation is
also involved in designing new low-head structures (e.g. St. Mary Diversion Dam near Babb, Montana and Blue
River Fish Barrier, eastern Arizona) where public safety should be incorporated at the design level.
There are likely a number of other Reclamation structures such as low-head diversion dams, drop structures,
grade control structures, and fish barriers that could cause a public safety risk. The purpose of this scoping level
study is to determine the extent of the problem within Reclamation (existing structures and new construction),
identify current research regarding retrofits and design guidance for safer structures, and determine if research
gaps exist where future research is warranted. All of Reclamation's regions will benefit from improvements in
public safety.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Public Safety of Reclamation Low-Head Dams (final, PDF, 1.4MB)
By Connie Svoboda, Jeffrey Riley, Nathaniel Gee,
Research Product completed on September 30, 2017

This research product summarizes the research results and potential application to Reclamation's mission.

Return to Research Projects

Last Updated: 6/22/20