VAl'J DUZEN RIVlill
Humboldt County
Stream Section :
Tribut-ary To:
Source of Data:
Acc essibility:
Remarks:
Source of Data:
Olmership:
From Highway 36 at Bridgeville to the state bridge on High\~ay
36 on the Blocksburg Quad, T1N, R5E, sect . 4.
Eel River
Personal observation; travel b;.' foot .
The primary accessibility to the portion of the Van Duzen
watershed surveyed is State Highway 36. The river is
accessible by High>:ay 36 for one mile upstream from the
state bl~dge at the town of Bridgeville. Further accessibility
to the river entails crossing private property . Logging roads
on the Cottrell Ranch provide access to the Van Duzen River for
approximately 6 miles upstream from the tmm of Bridgeville.
Upstream from the Cottrell RMch the river is accessible in t,;o
places by a private ro ad on the Eaton Roughs Ranch. The above
r;lentioned roads provide access to ,dthin 100- 200 yards of the
river .
The primary scope of t.his survey was t 0 note natural barriers to
upstream migrant salmonids and the extent of suitable spawning
areas . The survey included observations of aquatic life, both
vertebrate anti invertebrate, and wate r shed stream conditions .
Fersonal observation
The area l.;iGuediately s t:rroundL;g the stream in the portion
surveyed was privately o,-med. Farties o,ming the surrou11ding
terrain are Cottrell, Lucas, and Acsely.
DFlhhAGE DESCRIPTION
1•
Topography
A ,-,este rly trend in the river's coarse predominated in the portion
surveyed. Approximately 16 mil es of the river were surveyed over which
dista~ce it dropped from 2500 feet to 600 feet .
The stre&u is quite young ,
geologically speaking, a.'1d flows in a steep ;lalled, V-shapeci canyon .
Tributary streams ,{ere seen to be gene rally quite precipitous, especially
i ,1 the upper portion of the river surveyed.
2.
Vegetation
Fir, oak, pine, alder, en6. madrone trees 1;ere found in dense thickets along
l!luch of the river; heX-lever, open meadows were encountered as Vlell. These
grassland areas became more numerous as the lovrer end of the survey ,~as
reached.
Organic constituents of the soil were cieri ved fron decomposec sedL-n.elltarymetemorphic strata .
S'I'ill,Ah CCHDITIONS
1.
Streamside Vegetation
Virtt:.ally no vegetation '-las seen i mmediately
surrounding the stream ;:hich Vias in low water condition at the time of
survey .
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2.
Gradient
Although the stream averaged a 120 foot drop per mile of
stream in the portion surveyed, most of the total drop was attained in
the upper half "ihere Roughs and small falls ~iere c9.uite common .
3.
\ii dth
The vd,dth of this stream a verage about 15 feet but in many
places was seen to "iiden as t he main f low was broken up into t ,vo or more
smaller channels or was forced to f lO1"I around large boulders.
4.
Depth
foot i n
lJepth of the stream, at the time of survey , r anged from one
areas to an estimated 12 feet in many pools .
rif~le
Flow vlaS estimated at 40 c . f. s .
6.
Bottom
The bottom of both riffles and pools in this portion of the
Van Duzen consisted largely of one to three i nch rounded g ravel ,'lith
some coarse rubble in places . Sand and s ilted areas Vlere also encountered
but were restricted largely to the lovIer five miles of the survey . The
bottom type in potential spawning areas vias considered to be excellent.
No cementation of bottom material was encountered . Boulders c.ictated t he
streruns coarse to large degree in t he upper portion but became practically
nonexistent in the 10'l1er three miles of survey .
7.
Pool-riffle ratio r anged from 1: 1 in the upper regions " here the gr adient
lias fairly steep, to nearly 1 : 9 in the 10Vler porti ons v.nere the floVl \Vas
much mo re unifo rm due to lack of boulders in the stream. The pools present
were generally quite deep and large in surface area, ranging fro m fifteen
to fort y feet in diameter .
HABITAT SUITABllITY
All in a ll, t he Van I)uzen Hiver vias found to afford hi ghly suitable habitat
for salmonids . Pools were deep , large , and even though little overhanging
brush \Vas present, provided sufficient cover as nursery areas due to the
presenc e of large overhanging r ocks .
Aquatic invertebrates uere noted as being fairly abundant . Spro'ming areas ,
as has been indicated , were nu~erous and highly satisfa ctory .
FISllliRIES
Salmonids r a11.ging from one to t.,elve inches N'ere seen along t he entire
l ength of survey; hO~lever, they >!ere found to be more abundant in the
upper portions .
At the time of surve;r, SUllBller steel head were very abundant from the
" Salmon Hole" near Chimney Rock to approxilr.ately 2 miles dm;nstream.
SJuall suckers ( . 5 inches) we re seen t h roughout the surveyed portion .
STil.l.;,A,of OBSTRUCTIONS
Obstructions in this s t retch of river Here limited t o natural rock falls,
seven of ,;hich were recorded . (Please see separate sheet for detailed
descriptions) . Perhaps t he most important obstruction ~Ias the falls at
"Salmon, Hole" near Chimney Ro ck vThich create d a partial barrier to migratory
fish . This ,,,as evidenced by fact that the largest concentration of the
sunmer steelhead seen was in the pool innnediately belovl the falls . A f~1
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steelhead ;lere present above this point but certainly in no great numbers .
;-mo::.ARY
This report has been concerned with the 16 miles of Van Duzen River between
Bridgeville and the Dinsmore Bridge, all of \-lhich nOl'lS through private land.
This portion of the river \'{as seen to contain excellent habitat for
salmonid fisheries which, in fact, were seen throughout. Oaly the lower
six miles of the stream were available to anadromous fish at the time of
survey due to a falls approxhlately this distance from Bridgeville locally
knOl·m as "Salmon Hole" . Spawning and nursery areas were seen to be highly
desirable all along the stream but '''ere more abundant in the upper portions
due to a lack of material in the stream in the lower reguins to obstruct> .,-ater
flow. Salmonids ranging from one to t"lelve inches were seen throughout the
portion of river su rveyed and surrrrne r run steelhe ad 'jere seen up to the
aforementioned "Salmon Hole". Water flo" in the stream was estimated tobe
40 c . f . s . Pool to Riffle Ratio ranged from 1:1 in the upper regions to 1:9
in the louer .
SURVBY CRE.'1:l:
Del Hi§ks, Hike [',cCurdy, Jay Roberts, John Bellinger, Harold Cribbs ,
and Dan Nongol d .
DAtE OF SURVEY :
llliPORT BY:
June 29 , 1965
Dan Mongold .
VAN DUZEN RIVER OBSTRUCTIONS
Number
Description
1•
A rock falls 10 fe et in height ''las located approxmately
It rJiles upstream from 36 mile bridge . The falls
appeared to be impassable to sununer migrating fish .
2.
A 30 foot rockfalls, located approximately
above nt1Wer 1, appeared to be i mpassable to
migrating fish during summer flow .
3.
A 6 foot rockfalls , located approximately ~ mile
above nUlnber 2, appeared to be ir,lpassable to
migrating fish during 10';' flow periods .
1;
mile
A series of three rockfalls , located approximately
2 miles above nlli~ber 3, appears to be impassable to
to migrating fish during 10';' flow periods .
5.
A 12 foot rockfalls, located approxir.tately 3/4 mile
above number 4, appeared to be impassable to migrating
fish during low flow periods .
6.
A 10 foot rockfalls, located approxi:nately 3/4 mile above
number 5, appeared to be L npassable to migrating fish
during 10l" flow periods .
7.
A 10 foot rockfalls, located approxia ately 3~ miles
above nwnber 6, appeared to be impassable to migrating
fish during periods of 10l" flow .
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