Technical Rescue Interface: Swiftwater Rescue

Technical Rescue Interface: Swiftwater Rescue

Justin S. Padgett


Since the late 1960s, recreational river use has increased, and continues to do so. Equipment has become more user friendly, and skill development and experience has correspondingly grown. Classification of whitewater rivers has matured, and recreational users have been going further into remote places to navigate ever more difficult whitewater.

Swiftwater rescue was born out of a need to help ourselves and those traveling with us on rivers. As discussed in Chapter 16 (Management of Submersion Injuries) and Chapter 27 (Open Water Rescue), drowning is a leading cause of death worldwide. Currently, development in swiftwater education has led to the creation of swiftwater teams preparing for flood rescue around the world.

Swiftwater is unique, as its environment becomes more violent and challenging to navigate with increasing speed of current, steepness of elevation in the river bed, and increased volume of water. Drowning is often due to reasons beyond poor conditioning, medical emergencies, and lack of swimming skills. Drownings in swiftwater are commonly tied to long swims in difficult currents, entrapments while swimming and in watercraft, lack of equipment, inappropriate equipment usage, and lack of experience in swiftwater conditions.1

There are unique skill and equipment requirements for rescuers in swiftwater conditions. Specialized training accompanied with experience in swiftwater conditions is essential to rescue success. Much like the management of motor vehicle accidents, extrication will take precedence over medical care. With a focus on scene awareness and rescuer safety, most medical care will take place once the patient and rescuers are out of the water on the river shoreline.

Scope of Discussion

In this chapter, we will discuss in further detail the swiftwater environment and the rescue philosophy that this environment demands. We will discuss common group and personal equipment along with on water communications. Shoreline and water-based rescues, along with an abbreviated version of incident command, will illustrate the unique nature of swiftwater rescue. Note that incident command in WEMS operations is discussed in more detail in Chapter 3. Formal training and personal experience in swiftwater conditions is paramount to success with swiftwater rescue skills. This chapter serves as an academic overview for this area of special rescue, but cannot replace hands-on training, and ideally certification in a standardized swiftwater rescue curriculum, such as Swiftwater Rescue Technician. In closing, we will integrate the understanding of medical care provided by swiftwater responders.


As mentioned in Chapters 16 and 27, drowning data in the world have discrepancies in the language used, methods for collecting
data, and categories used to funnel that data. We know that the World Health Organization (WHO) and United States Centers for Disease Control (CDC) have identified drowning as a leading cause of death, with numerous causal categories ranging from bathtubs to the ocean. WHO reports over 327,000 persons per year die from drowning, and CDC asserts that the percentage of drownings in natural water settings, including lakes, rivers and oceans, increases with age. More than half (57%) of both fatal and non-fatal drownings among those 15 years and older occurred in natural water settings.2 Drowning prevention in the United States focuses on prevention measures that include learning to swim, barriers for swimming pools, and increased supervision by lifeguards for medical emergencies such as seizures. Unfortunately, these drowning prevention factors are not as common in the remote swiftwater environment. This is unfortunate, as strainers and sieves, flush drownings, poorly fitted lifejackets, and low head dam entrapments remain at the top of the list of causes of death and disability in whitewater as reported by the American Whitewater Association (AWA).3 The AWA has kept data on river accidents since 1973. The data further reveal that fatalities in the recreation whitewater boater population has risen and fallen over that period, with a large spike in 1999, an all-time low in 2004, and then the highest recorded incidence in known history in 2012. Conclusions from analysis of their data suggest an increase in accidents and fatalities in years when local rainfall has been exceptionally heavy.

Care Environment

Rescue in the swiftwater environment can be broken down into whitewater (or “swiftwater”) rescue and flood rescue. Although there are numerous similarities, the flood environment is less predictable in its crosscurrents, and moving obstructions and human-made debris making it more challenging to navigate for the rescuer. Whitewater river environments have recognizable features such as waves, hydraulics, eddy currents, confluences with additional streams of water, undercut rocks, boulder piles, trees, and vegetation that create obstructions. These features are also more predictable in that they change less often, whereas by definition flood features may be recently formed by flooding and may rapidly change.

Water follows the path of least resistance and seeks the lowest point of gravity. It weighs 8.33 lb per gallon, making any fully or partially submerged object much heavier than it would be empty on the surface. Additionally, water volume in a river bed is measured in cubic feet per second, or cfs, which is calculated by the following formula: width × depth × speed. Monitored streams will have nationally available reports of flow or volume in cfs. Often the cfs expressed by river gauges that are referencing a specific river section do not precisely correspond to the cfs at the rescue site; nonetheless, they will provide a foundation of river conditions to be expected. As speed doubles, the force of water quadruples, making fast water very powerful as it moves through a high gradient. The higher the volume, the greater the gradient, and the larger the obstructions, the greater the whitewater hazards.

Rescuers must be familiar with reading the water in the river environment. This understanding helps the rescuer make navigation decisions in the water and aids in the anticipation of outcomes with specific technical skills. The following are common terms used to describe river features.

Eddies are a horizontal reversal of water flow where the pressure of current along an obstacle (such as a rock) causes the water behind the obstacle to reverse flow upstream (Figure 26.1). These are rescue staging and break areas along the river flow. Eddies create eddy lines—obvious lines in the river where current moves in opposite directions on each side of the line (Figure 26.1). This current differential between an eddy and downstream current ranges from a gentle surface line to a wall of water dropping around the obstacle and recirculating horizontally. Swimming and paddling require the understanding of eddy lines, so they can be crossed efficiently.

A hole or hydraulic (Figure 26.1) is a vertical reversal of water flow where the pressure of the current falling over a gradient (such as a dam) causes the channel water at the base of the gradient to be forced downward into a loop style reversal and back to the surface. At the surface, part of the water continues downstream and part reverses back upstream to the base of the gradient. This reverse flow tends to be hazardous, because it can cause an object to be recirculated (stopped or kept) in the hydraulic—hence the commonly used name stopper or keeper. The churning whitewater of a hole consists of between 40% and 60% air. As a rule of thumb, when you look downstream, a frowning hole is a natural hydraulic whose outer edges curve upstream. When viewed from upstream, it has the appearance of a frown. A frowning hole tends to be a keeper by recirculating on itself. In contrast, a smiling hole is a natural hydraulic whose outer edges curve downstream. When viewed from upstream, it has the appearance of a smile. A smiling hole tends to flush a patient or object free due to the downstream current at its sides.

Standing waves are a rhythmic series of waves caused by the convergence of main channel currents as the result of rising river water, or underwater obstacles or ledges.

Increasing river gradient or increased volume converts the hydraulic effect of holes to a wave or series of waves that form downstream from the gradient. A downstream “V” in the river creates a hydraulic effect in the form of a “V” pointing downstream (Figure 26.1). This is caused by the convergence of downstream water flow into the channels of least resistance. The largest series of “Vs” pointing downstream indicates the main channel. By contrast, an upstream “V” creates a hydraulic effect in the form of a “V” pointing upstream which is caused by downstream water flow up and around an obstacle (Figure 26.1).

FIGURE 26.1. Basic hydrology. Courtesy of Dave Bradford and Landmark Learning.

Strainers, sieves, and undercut rocks are river entrapment hazards. Strainers are a buildup of tree and shrub debris that may run deep in the water restricting downstream flow (Figure 26.1). Sieves are a buildup of boulders, sometimes mixed with strainers, that restrict downstream flow (Figure 26.1). Both of these entrapment hazards shift with high water and cannot always be readily seen from the surface of the water. Expect that after high water these obstructions may have shifted in the river to the outside of river bends. When rocks are carved by the force of water over time, a submerged hazard is created. An undercut rock is defined by water flushing under the rock, often with the absence of a water pillow on the face of the rock and an eddy replaced by downstream current on the backside of the rock (Figure 26.1). These hazards may drag an unsuspected swimmer under the rock along with other debris that may be held there.

A confluence is a flowing together of streams where two bodies of water converge (Figure 26.1). This feature could be hazardous at high water levels causing a disorganized and powerful current. What initially may be disguised as an eddy ends up being a forceful crosscurrent creating undertow as it forces its way downstream.3

The International Scale of River Difficulty, as described by the AWA, categorizes rivers based on their difficulty to navigate. Class I rapids are described as fast-moving water with riffles and small waves. Few obstructions are present, all of which are obvious and can be easily avoided with little training. Risk to swimmers is slight; self-rescue is easy.

Class II rapids are straightforward rapids with wide, clear channels which are evident without scouting. Occasional maneuvering may be required, but rocks and medium-sized waves are easily avoided by trained paddlers. Swimmers are seldom injured and group assistance, while helpful, is seldom needed. Rapids that are at the upper end of this difficulty range are designated “Class II+.”

Class III rapids become more challenging to navigate, with moderate, irregular waves that may be difficult to avoid and are capable of swamping an open canoe. Complex maneuvers in fast current and good boat control in tight passages or around ledges are often required; large waves or strainers may be present but are easily avoided. Strong eddies and powerful current effects can be found, particularly on large-volume rivers. Scouting is advisable for inexperienced parties. Injuries while swimming are rare; self-rescue is usually easy, but group assistance may be required to avoid long swims. Rapids that are at the lower or upper end of this difficulty range are designated “Class III−” or “Class III+,” respectively.

Rescuers will find that Class IV rapids test the limitations of most rescues. In Class IV rapids, intense and powerful but predictable rapids requiring precise boat handling in turbulent water. Depending on the character of the river, it may feature large, unavoidable waves and holes or constricted passages, demanding fast maneuvers under pressure. Rapids may require “must” moves above dangerous hazards. Scouting may be necessary the first time down. The risk of injury to swimmers is moderate to high, and water conditions may make self-rescue difficult. Group assistance for rescue is often essential but requires practiced skills. Rapids that are at the lower or upper end of this difficulty range are designated “Class IV−” or “Class IV+,” respectively.

Class V rapids are extremely long, obstructed, or very violent rapids which expose a paddler to added risk. Drops may contain large, unavoidable waves and holes or steep, congested chutes
with complex, demanding routes. Rapids may continue for long distances between pools, demanding a high level of fitness. The eddies that exist may be small, turbulent, or difficult to reach. At the high end of the scale, several of these factors may be combined. Scouting is recommended but may be difficult. Swims are dangerous, and rescue is often difficult or impossible even for experts. Because of the large range of difficulty that exists beyond Class IV, Class V is an open-ended, multiple-level scale designated by subdivisions using Arabic numerals and decimal classifications, such as 5.0, 5.1, 5.2, etc. Each of these levels is an order of magnitude more difficult than the last; for example, increasing difficulty from Class 5.0 to Class 5.1 is a similar order of magnitude as increasing from Class IV to Class 5.0.

At the extreme end of river navigation are Class VI rapids. These runs have almost never been attempted and often exemplify the extremes of difficulty, unpredictability, and danger. The consequences of errors are very severe and rescue may be impossible. These rapids should be run by teams of experts only, at favorable water levels, after close personal inspection and taking all precautions. After a Class VI rapids has been run many times, its rating may be changed to an appropriate Class 5.x rating.3 This scale of difficulty leaves much room for subjective assessment, making one person’s Class III another person’s Class V.

Time in the river environment in different conditions aids in evaluation and judgment of river conditions, which may change with melting ice, rainfall, or dam breaches far upstream. Be aware of steep canyons below large land masses that have histories of flash flood. Steep rivers and creeks may create a need for vertical or low angle rescue skills in addition to the other hazards described previously. High and low angle rescue is specifically discussed in Chapter 25.

Rivers that are not dam controlled but dependent on natural flow may be less predictable than standard flows on dam-released rivers under normal weather conditions. In dam-released rivers, the water will have a designated start and shut off time, which could be adjusted in the time of emergency to assist the rescue effort. In addition, dam-released rivers can be used for WEMS training, with releases timed and engineered to generate flow characteristics and cfs volume to replicate various operational situations.

Consider that air temperature and wind speed will have a rapid cooling effect on both patients and rescuers, turning a functional rescuer into a patient quickly. Finally, inadequate lighting due to the time of day or angle of light in deep river gorges may limit visibility and shorten the window of rescue potential.

Environmental Teams

Swiftwater teams commonly take two forms:

1. rescue teams made of persons traveling on the river (referred to in the following as “recreational rescuers”); and

2. professional teams made up of rescuers who are associated with county, state, or federal rescue agencies.

Both teams are important in the niche of swiftwater rescue. Recreational rescuers are often at the scene when the event occurs, making their timeliness for action a great benefit for preventing fatalities. These rescuers are commonly adept at quick, low tech rescue with few resources, and their accident assessment and river navigation skills may actually exceed those of professional rescuers.

Professional rescue groups benefit from increased personnel numbers, specialized equipment, and transportation resources. In addition, these professional rescuers, as formal EMS responders, are part of a larger rescue and medical system able to call for air medical support, and mutual aid from neighboring counties, states, or other federal agencies.

The downfall of professional rescuers in this setting may be lack of training, experience, and comfort in the whitewater environment. Additionally, these specialized teams will take time to physically form before deploying to the rescue scene.4 When speed makes the difference between a rescue and body recovery, the recreational rescuers may be the only personnel capable of intervening quickly enough (remember, as discussed in Chapter 16, that fatal drowning occurs after only minutes of submersion, often before a professional WEMS team can be deployed). Often when recreational rescuers are unsuccessful, professional rescue teams are deployed for body recoveries.


Technical rescue skills used in river rescue are dependent on experience, training, continuity of training, water conditions, and access from shore. Swiftwater rescue ranges on a scale of simple patient assists to technical rescues requiring specialized equipment and coordination with other rescuers. Rescuer safety is paramount and must remain a focus for all rescuers in this environment. Well-intentioned persons and sometimes trained rescuers are killed in the line of rescue due to inappropriate equipment or overwhelming environmental conditions.4 Rescuers in this setting do well to develop a sense of “river judgment” through training, practice, and personal and group experience. Good decisions are often born from previous bad experiences.

Oct 16, 2018 | Posted by in EMERGENCY MEDICINE | Comments Off on Technical Rescue Interface: Swiftwater Rescue
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