H a z a r dM a n a g e m e n ta n dP u b l i cWa r n i n g

TABLE 3.U.S.AVALANCHE DANGER SCALE (1996)

Danger Level

(& color)

(what)

Low
(green)

Moderate
(yellow)

Moderate
to High
(orange)

High
(red)

Extreme
(red w/black
border)

Avalanche Probability

and Trigger

(why)

Natural avalanches
very unlikely.
Human triggered
avalanches unlikely.

Natural avalanches
unlikely.Human
triggered avalanches
possible.

Natural avalanches
possible.Human
triggered avalanches
probable.

Natural and human
triggered avalanches
likely.

Widespread natural
orhuman triggered
avalanchescertain.

Degree & Distribution

of Avalanche Danger

(where)

Generally stable
snow. Isolated areas
of instability.

Unstable slabs
possibleon steep
terrain.

Unstable slabs
probableon
steep terrain.

Unstable slabs
likelyon a variety
of aspects and slope
angles.

Extremely unstable
slabscertainon most
aspects and slopes.
Large destructive
avalanches possible.

Recommended

Action

(what to do)

Travel is generally
safe.Normal
caution advised.

Use caution in
steeperterrain on
certain aspects
(defined in accom-
panying statement).
Be increasingly
cautious in steeper
steeperterrain.

Travel in avalanche
terrain is not recom-
mended.Safest
travel on windward
ridges of lowerangle
slopes w/o steeper
terrain above.

Travel in avalanche
terrain should be
avoided.Travel con-
fined to low angle
terrain well away
fromavalanche path
run-outs.

Class 5- Roped climbing requiring protection such as run-
ners, artificial chocks, and pitons,as well as belays.

Class A- Roped climbing with an artificial assist,such as
stepping on a piton or climbing a chain of slings or pre-
tied stirrups.

Scouting is mandatory forall but the best paddlers.A
solid roll is a necessity.

Class 5- Class 5 is essentially the upper limit of what can
be run without serious risks, even by experts.Scouting
is a must.The rapids are exceedinglycomplex and tur-
bulent.Holes may be very large andnasty.Youhave to
be"spot-on"torun Class5water.The price fornot
being exactly where you want to be can be high.

Class 6- Basically unrunable.Niagara Falls, forexample,
qualifies quite admirably for a Class 6 rating.Someone
claiming to run Class 6watereitherissuicidal
or,more likely, has overrated the water.
Neitherscale specifically addresses relative risk,but the
concept is implicit in each.For thepurposesof describing
avalancheterrain risks, the river scale was found to be the
closestmatch.Itwasobservedthatthesamesortsof
featuresthatcancause severeinjuryordeathinrivers
compare favorably to similarfeatures on avalanchepaths.
These include rocks,trees,drops,deep holes,strong hy-
draulic forces and late rescue forriverenvironments; and
rocks,trees, cliffs,deep burials,avalancheforces and late
rescue foravalanchepaths.The ATR Scale, therefore,as-
signs levels of relative risk of severe injury or death to site-

3

TABLE 5.

RIVER RATING SCALE

Class 1- Slow-moving water with fewor no obstacles.Easy
to read, easy to paddle.

Class 2- The wateris faster andthe river makes afew bends.
Rocks,holes,and waves are presentbut recognizable
from upstreamand easilyavoided.Requires basic white
water skills.

Class 3- The current is fasteryet,and rocks,waves,and
holes increasein bothnumber andsize.Routes are fairly
apparent,butshorescouting isadvisable.Areliable
rollishighlyrecommended.Yourwhitewaterskills
should be in good shape.

Class4-Thewaterisdifficult,big,orboth.Holesand
waves may be quite big,and finding a clean route will
require somedetectiveskill.Shouldyougetoff-line,
there is a possibilityof getting trashed.