Recreational Use Considerations in Planning and Permitting of Low Head Dams

by Michael G. Donahue, Esq. and T. Andrew Earles, Ph.D.


Public safety is of paramount importance at all hydraulic structures and reservoirs. Planners, owners and operators of these structures must perform a careful evaluation to identify known and potential significant public safety hazards to the public associated with the structure, its operation and the surrounding area. Once identified, reasonable measures should be taken to eliminate these hazards together with the a comprehensive safety program to warn and protect the public from remaining hazards.

In 1992, the Bureau of Reclamation’s Public Safety Around Dams and Reservoirs: An Interim Working Guideline (BOR, 10/92) defined a “significant public safety hazard” as a site or condition where there is a reasonable potential for a person to suffer injury or death because of a hazardous condition present at the site. A well recognized significant public safety hazard of dams and other hydraulic structures is structural failure. A less recognized, but also significant, hazard is the potential for injury or death to recreational users of the reservoir or surrounding area as a result of dangerous hydraulic conditions created by the structure.

Paddle sports and other water based recreational activities have dramatically increased in popularity over the past twenty years. The American Canoe Association reports that Forty Eight million Americans experienced canoeing, kayaking and other paddle sports in 2002. Of these, four million people consider themselves avid paddlers. In addition, specific activities have surged substantially in popularity. For example, kayaking has experienced a growth of 185% during the past seven years.

It is expected that participation in kayaking, canoeing and boating will continue to increase. The barriers of entry to these sports have fallen. Kayaks, canoes and other craft are becoming less expensive and commonly available through “super” sporting good stores. As it becomes easier to experience and enjoy these activities, it should be expected that the knowledge and training of the average entry level participant will likely be low as there is no formal training, certification or license requirements for such operators of these crafts.

Additionally, many members of the general public find themselves closer than ever to seemingly safe and suitable reservoirs and other waterways for recreational activities. As the population density of the United States continues to rise, previously remote waterways and hydraulic structures are now easy to access and have neighbors to residential communities. Reservoirs, waterways and other areas near dams are popular locations for recreational activities. Further, new hydraulic structures which change the character of the waterway may “create” new opportunities for recreation.

The growth in popularity of recreational activities and an increasing use of reservoirs associated with hydraulic structures, there has been a corresponding increase in the number of incidents and fatalities related to the use of these facilities. (BOR, 10/92) It is an unfortunate truth that unskilled, novice recreational users may not recognize the serious threat posed by some innocuous appearing hydraulic structures. While high dams and spillways present an imposing facade, low head and small diversion dams and weirs do not appear menacing. (FERC, 3/92) The placid, shallow water in areas surrounding such structures can lull the novice into a false sense of security. Short drops over low heads during high water can seem harmless, much like a waterside at an amusement park.

While the water downstream of a low head often appears harmless, the plunging water flow over the dam may result in turbulent, hazardous conditions which can be deadly. Under certain flow conditions, a “reverse flow” or “reverse roller” are created. These flow conditions carry objects back towards the face of the dam where they are subject to the water falling over the crest. Objects (or persons) are then submerged by the falling water only to resurface and recirculated towards the face of the dam by the “reverse roller.” The uniform nature of the current along the length of the structure makes escape or rescue difficult and sometimes impossible. (Chambers, 6/03)

The hidden, deadly hydraulic hazard of the “reverse roller” has claimed many lives of paddle sport participants as well as those who have tried to rescue trapped victims. While it is impossible to estimate the number of fatalities which have arisen from recreational activities near low head dams and other water control structures, statistic obtained from specific rivers support the significance of the public safety hazard. Twenty nine (29) people died on the Fox River in Illinois over a ten year period.

As the popularity and participation in water based recreation increases, the designers, builders and owners of water structures must recognize the potential that the public may intentionally or unintentionally encounter their structures during recreational activities. A review of the current dam safety permitting regulations reveals that most do not require planners, designers or owners to address the potential hazards created by the structure to recreational users of the waterway and surrounding areas. Also most often absent from these regulations is any requirement that designers and owners create and implement a safety program to reduce the risk to recreational users.

Hazard Potential Classification and Permitting

To examine recreational use considerations in the dam permitting process, the authors reviewed federal and state guidance on hazard potential classification of dams and dam construction permitting requirements. Dam hazard potential classification is typically a centerpiece of a dam construction permit application and is a well-known measure of the potential for a dam to cause loss of life or damage to property. The basis for dam classification is described in the Federal Emergency Management Agency (FEMA) Federal Guidelines for Dam Safety: Hazard Potential Classification Systems for Dams (FEMA 1998):

Common practice among federal and state dam safety offices is to classify a dam according to the potential impact a dam-failure (breach) or mis-operation (unscheduled release) would have on upstream and/or downstream areas or at locations remote from the dam.

States have a variety of classification systems (some numerical, some “low” to “high” hazard ratings, etc.); however, all share common elements, relating the hazard potential to dam characteristics including height, storage volume, drainage area and upstream and downstream river and floodplain characteristics including residential development and vital infrastructure. The hazard potential classifications characterize potential loss of life of damage to property resulting from a breach or uncontrolled release, but do not necessarily provide an accurate characterization of hazards arising from typical dam operation. Typically, low head dams are not classified as high potential hazards, since, by definition, the height of the dam is limited. Nonetheless, such dams can be very hazardous to recreational users because of hydraulic conditions such as the reverse roller.

State and federal dam hazard potential classifications are not entirely devoid of recreational considerations–the State of New Jersey Dam Safety Standards(State of New Jersey 2000, N.J.A.C. 7:20-1.8 (a) 1. iii) has provisions for consideration of recreational facilities along rivers in hazard potential classification. The Federal Energy Regulatory Commission (FERC) and United States Department of Agriculture (USDA) Soil Conservation Service (SCS, now Natural Resource Conservation Service [NRCS]) also address recreational facilities in hazard potential classification (FERC, 1991 and USDA, 1981). While these hazard potential classification guidelines do raise the issue of recreational use of rivers near dams, it is only in as much as the facilities or users of the facilities would be impacted by a breach or unscheduled discharge.

Dam construction permit applications requirements vary from state-to-state but typically request information on dam location, design parameters, hazard potential classification, and hydrologic and hydraulic analysis related to the design. Of the more than forty state applications surveyed by the authors, none requested that the applicant specify the recreational use classification (if any) of the river to be dammed. While one would hope the applicant and design engineer would take the recreational use classification of a waterway into consideration in evaluation of public health, safety and welfare implications of a proposed dam, drownings in states including Oregon, New Jersey, Illinois and West Virginia demonstrate that this is not always the case.

Wisconsin has regulations which address recreational considerations in the vicinity of dams. These regulations establish procedure and criteria for use in evaluating boating use and hazards around dams. They also address warning signs, portages and navigation at these structures to minimize the risk of exposure by the general public. The procedure, however, places the burden on the state to inspect the dam with the owner and issue an order to the owner specifying warnings signs and devices, portage requirements and signs at dams. (Wisconsin Administrative Code, Chapter NR 330, Warning Signs and Portages For Dams)

Of the state construction permit applications surveyed, only Pennsylvania’s application directly addressed recreational use. In the “Project Description Narrative” section of the permit application, the permit application guidance states “the narrative must also describe in detail what effects the project will have on public health, safety and the environment.” (Commonwealth of Pennsylvania 1998) This information is obtained by completing an Environmental Assessment, which is required for all dams that are regulated by the Pennsylvania Department of Environmental Protection (DEP). The Environmental Assessment specifically addresses recreational uses in the dam permitting process:

Recreational boating may also need to be considered, regardless of the official designation, where there is documented on-going use of the watercourse for boating, canoeing or other types of regulations, (Commonwealth of Pennsylvania 2001).

The direct reference to recreational uses in the Pennsylvania dam permitting process enhances dam safety by bringing these considerations to the attention of the applicants, engineers and regulators. Wisconsin requires the state to inspect dams and monitor safety programs, but this procedure is outside the permitting process. It is conceivable that other states’ dam safety programs require such environmental assessments that have similar requirements for consideration of recreational uses; however, none are directly evident as a part of the permitting process.

Recommendations for Recreational Use Considerations in Permitting

Public safety would be well served by state permitting regulations which require formal consideration by the applicant of the hazards present to recreational uses near low head dams and other such structures. Regulations should be considered which require an assessment of the recreational uses of an area and require applicants to expressly recognize hazards posed to recreational users. Applicants should also evaluate the areas where potentially hazardous waters may pose serious threat to users. Access should be restricted to these areas through the use of warnings as well as physical barriers and obstructions. These could be appropriately presented and considered as part of the application for permit approval. Permitting regulations place the appropriate burden on the applicant to address these concerns, rather than requiring the state to initiate and maintain inspection and evaluation procedures.

Initially, the environmental assessment should be required to include identification of recreation uses of the area in and around the proposed project which may be potentially impacted. The individual or team responsible for this assessment should determine the relevant communities and resources from which to obtain specific information with regard to the recreational uses of the surrounding area. This analysis can begin by simply utilizing a map which identifies state and local park and recreational areas. In addition, relevant national, state and/or local associations such as the American Canoe Association can also be consulted to develop a comprehensive listing of the type and frequency of recreational uses.

A site inspection can be used to specifically identify recreational uses. The location of boat ramps, canoe drop-in points and portage paths, and any other physical characteristics of the project area should be identified as they often provide important evidence of specific types of use. (BOR 1992; FERC 1992) Public meetings convened to address other aspects of the assessment and design plan can be used to obtain input from the community with regard to recreational uses.

The information gathered through these inquiries should be summarized and set forth in the environmental impact or assessment statement. This allows for consideration of the potential and actual recreational uses in the surrounding area when the hydraulic design is proposed, revised, and finalized.

Once the uses of an area are identified, the applicant should identify potential hazards posed by the project to recreational users at or near the project area. This should include an evaluation of how the project area may be used for recreational activities and the potential for users to be exposed to known and potential hazards. Some hazard are present as a result of the design and function of the structure. Others may arise from site specific characteristics of the surrounding area. For example, projects such as low head dams may create dangerous downstream turbulence capable of entrapping small crafts such as canoes or kayaks. The applicant should evaluate whether there is a reasonable likelihood that recreational users will be exposed to this hazard. Lastly, a determination should be made regarding the most appropriate means to safeguard the general public from potential hazards created by the project.

The most effective way to minimize risk at a low head dam or other structure would be to completely eliminate access by the general public to the dam and the waterway. (BOR, 1992) Most often this is not practical due to economic, political and other considerations. States should consider regulations which require applicants to evaluate the project area to evaluate the potential for the presence of and exposure to hazardous waters and conditions. Applicants should also be required to propose and implement methods to restrict access to these hazardous conditions. This recommendation is based upon U.S. Army Corps of Engineers regulations and manuals.

All Corps of Engineer owned dams and other civil work structures must be evaluated to identify hazardous waters, both upstream and downstream of the project structure, and designate these as “restricted areas.” (ACE ER 1130-2-341) Hydraulic criteria and operational considerations can be used to determine the extent of the restricted area for a particular structure. It is imperative that hydraulic engineers have some input in determining the means to best limit exposure of the general public to hazards such as reverse rollers and other dangerous conditions. (ACE EM 1116-2-1605)

The “hydraulic line” is used to fix the minimum size of a restricted area. The Corps of Engineers defines the hydraulic line based upon characteristics and criteria specific to the project and its surrounding area. These lines create border upstream and a border downstream between which access is prohibited to members of the general public. The waters between these lines present the most significant hazards from turbulence. These location can be determined by data from site specific model studies and/or hydraulic jump or other appropriate calculations. (ACE ER 1130-2-341)

The minimum size of the restricted area can be defined by the upstream and downstream hydraulic line. The Corps also recommends that the restricted area should include a buffer zone beyond the hydraulic line. A buffer zone will provide a factor of safety consistent with certain general principles as well as the operational characteristics of the structure. The buffer zone beyond the hydraulic line upstream of a structure must be sufficient to allow a boater to reach the shore before being carried by currents into the dam or other structure. It should also allow a reasonable expectation of a rescue in the event of a boating accident or equipment failure. (ACE ER 1130-2-341)

Downstream restricted areas must be sized to include a buffer zone which will prevent a boat that is without power or a swimmer from being drawn into the structure. All turbulent waters caused by the operation of the structure must be encompassed by the restricted area as they pose significant risk of swamping or capsizing small boats. (ACE ER 1130-2-341)

Final determinations regarding the boundaries of the restricted area are based upon the operational considerations of the project. While this most certainly can be performed during the design plan stage of the project, these considerations must be revisited following the commencement of operation to determine whether the operation varies from assumptions made during design. It is recommended that a review of operational considerations is prescribed on a regular basis to assess and allow for any changes which occurred during operation. (ACE ER 1130-2-341)

Corps regulations also recommends that methods are proposed and inCorpsorated to warn the public of hazardous waters and conditions and limit access to restricted areas. Generally, the use of buoys, floats, physical barriers, audible warning devises, and other measures should be considered. These should include measures to prevent access to identified restricted areas from the structure, adjacent banks and the waterway, both upstream and downstream.

The authors recommend that states consider expressly requiring applicants to identify the recreational uses of the affected waterway and its surrounding area. Further, states should consider implementing regulations which require applicants to evaluate, establish and maintain “restricted areas” and methods to inform and warn the public of these significant safety hazards to reduce the potential for exposure to hazardous waters surrounding low head dams and other projects. The Corps regulations provide a potential model from which state regulations can be developed.

There are numerous benefits that may flow from additional regulation addressing this topic. By including a requirement as part of the permitting process, the state agency stimulates and assures that the applicants’ assessment and design process to address the problem of hazardous waters present as a result of a new project. By demanding that consideration to be given these issues before the permit is actually granted, there is a greater liklihood that appropriate measures will be in place when construction is completed and operation commences. Lastly, permiting regulations would place the burden on the applicant, rather than the state, to initiate and develop safe practices.


Water based recreational activities are enjoyed by millions of Americans every year. Unfortunately, many novice enthusiasts fail to understand the significant danger created by otherwise unassuming hydraulic structures such as low head dams. Further, hydraulic engineers designing these structures may not appreciate the recreational activities enjoyed in the vicinity of proposed structures. By requiring an identification and assessment of the recreational uses near a structure, state dam safety regulation can focus attention on the potential for tragedy and provide a framework to assure safe and adequate planning and restrictions on access.


  • Bureau of Reclamation 1992, Public Safety Around Dams and Reservoirs: An Interim Working Guidline, BOR Dam Safety Inspection Section.
  • Commonwealth of Pennsylvania 1998. Instructions for Completing Dam Permit Application. Commonwealth of Pennsylvania, Department of Environmental Protection, Bureau of Waterways Engineering, Instructions 3140-PM-WE0001 Rev. 3/98.
  • Commonwealth of Pennsylvania 2001. Environmental Assessment Form (E.A. Form) Instructions. Commonwealth of Pennsylvania, Department of Environmental Protection, Bureau of Waterways Engineering, Instructions 3930-PM-WE0017 Rev. 11/2001.
  • Chambers, Virgil. Low Head Dams: A Not-So Clear and Present Danger,, National Safe Boating Council, June, 2003.
  • Federal Emergency Management Agency (FEMA) 1998. Federal Guidelines for Dam Safety: Hazard Potential Classification Systems for Dams. FEMA Mitigation Directorate, prepared by the Interagency Committee on Dam Safety.
  • Federal Energy Regulatory Commission (FERC) 1991. Engineering Guidelines for the Evaluation of Hydropower Projects. FERC Office of Hydropower Licensing , FERC 0119-2.
  • Federal Energy Regulatory Commission (FERC) 1992. Guidelines for Public Safety at Hydropower Projects. FERC Division of Dam Safety and Inspections.
  • State of New Jersey 2000. Dam Safety Standards. N.J.A.C. 7:20, Effective Date: April 28, 2000, Readoption; June 5, 2000, Amendment; Expiration Date:April 28, 2005.
  • U.S. Army Corps of Engineers (ACE), Hydraulic Design of Navigation Dams-Engineer Manual, EM1110-2-1605, 12 May 1987.
  • U.S. Army Corps of Engineers (ACE), Hydraulic Design of Spillways-Engineer Manual, EM1110-2-1603.
  • U.S. Army Corps of Engineers (ACE), Restricted Areas for Hazardous Waters at Dams and Other Civil Work Structures, ER 1130-2-341, 1 Feb. 1991
  • United States Department of Agriculture (USDA) Soil Conservation Service (SCS) 1981. TSC Technical Note – ENG LI-43, Re: Hazard Classification of Dams. USDA SCS, Lincoln, NE.

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