USDA Forest Service Research Note. PSW-RN-426. 2004. 1

Wooster, John; Hilton, Sue. 

2004. Large woody debris volumes 

and accumulation rates in cleaned 

streams in redwood forest in southern Humboldt County, California. 

Res. Note PSW-RN-426. Albany, 

CA: Pacific Southwest Research 

Station, Forest Service, U.S. Department of Agriculture; 16 p. 

Large woody debris (LWD) 

was inventoried in 1999 in 

five streams where LWD was 

removed in the early 1980s, and 

no LWD has been artificially introduced since. All study sites 

are second order channels near 

the confluence of the South Fork 

and main-stem Eel River, California. Watershed contributing 

areas range from 4.7 to 17.4 km2, 

and mean active channel widths 

within study reaches range 

from 5.6 to 8.4 m. Vegetation is dominated by redwood 

(Sequoia sempervirens (D. Don) 

Endl.); three streams have 

old- and second-growth study 

reaches and two streams are 

entirely second growth. LWD 

volumes in old-growth reaches 

averaged 589 m3/ha compared 

to 251 m3/ha for second-growth 

Introduction

Large woody debris (LWD) is a fundamental component of streams in forested 

watersheds. LWD can provide stability to the streambed and banks, influences the routing of sediment, promotes pool formation, provides nutrients 

for aquatic invertebrates, and is an essential element of quality anadromous 

fish habitat (Bilby and Likens 1980, Harmon and others 1986, Bisson and others 

1987). The complex input and output relationships that determine a stream’s 

LWD “standing crop” are often affected by land use practices. Murphy and 

Koski (1989), using a model developed for undisturbed old-growth streams in 

southwest Alaska, predict that in the 90-year period following clear-cut logging without a streamside buffer strip, LWD would be reduced by 70 percent 

and recovery to pre-logging levels would take more than 250 years. Andrus 

and others (1988) report that in a small coastal Oregon watershed riparian 

trees must grow longer than 50 years to supply an adequate volume of LWD. 

Documenting accumulation rates of LWD in streams with different forest 

management practices is important for understanding how land management 

affects stream ecosystems.

Before the positive aspects of wood in streams were widely understood, 

LWD was considered deleterious to anadromous fish because it formed (continued on page 2)

United States

Department

of Agriculture

Forest Service

Pacific Southwest

Research Station

http://www.fs.fed.us/psw

Research Note

PSW-RN-426

February 2004

Large Woody Debris Volumes and Accumulation 

Rates in Cleaned Streams in Redwood Forests 

in Southern Humboldt County, California

John Wooster and Sue Hilton

Old growth (L) and second growth (R) redwood streams with "cleaned" LWD in foreground and recently 

recruited LWD spanning the channel in the background. (1.5 m stadia rod for scale).
2 USDA Forest Service Research Note. PSW-RN-426. 2004.

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

potential migration barriers and contributed to increased bank erosion 

attributed to deflected flow. Early salmonid restoration efforts focused on 

removing LWD from streams, a practice known as “stream cleaning.” Floods 

in the north coast region of California in 1955 and 1964, combined with 

intensive logging, delivered large volumes of LWD to streams. The Energy 

Resources Fund of 1980 and the 1981 Bosco-Keene Assembly Bill 951 allocated 

one million dollars per year for salmon restoration. As part of the salmonid 

restoration plan, streams were to be cleaned at the rate of at least 100 miles per 

year (California Resources Agency 1982). Early stream cleaning efforts often 

removed all LWD below a stream’s high water mark. By 1986-87 the stream 

restoration paradigm began to shift towards selectively removing debris jams 

while strategically replacing LWD as instream structures.

This study investigates cleaned streams in order to measure current LWD 

loads and to quantify LWD accumulation rates since cleaning. Study sites 

with no instream structures were selected to minimize artificial contributions 

to accumulation rates. Stream cleaning provides a reference point to measure 

rates of LWD deposition. Accumulation rates were estimated based on accrued 

LWD volumes and time elapsed since cleaning. Accumulation rates and volumes were compared between channels adjacent to unharvested old-growth 

(OG) redwood stands and channels in managed second-growth stands. The 

results provide information on how quickly cleaned reaches are recovering, 

and how much additional LWD is required to compensate for diminishing 

potential recruitment volumes following conversion from old-growth to second-growth forests.

Study Sites

Five streams in or bordering Humboldt Redwoods States Park (HRSP) in southern 

Humboldt County, California were selected as study sites (fig. 1). The two primary 

selection criteria were: 1) extensive stream cleaning pre-1986 and 2) no installation 

of instream structures. Vegetation in all study sites is dominated by redwood. 

Bridge, Elk, and Fish Creeks are tributaries to the lower South Fork (SF) Eel River 

and are partially in HRSP. The reaches within HRSP boundaries are unharvested 

old-growth (OG) redwood. Old-growth reaches begin at the confluence with the 

SF Eel River and extend upstream 500 to 800 meters. All stream channels within 

old-growth boundaries were cleaned. Above park boundaries, cleaned reaches 

Figure 1—Location of five study 

sites in southern Humboldt County, 

California

reaches. The mean volumes 

in cleaned old-growth streams 

were significantly less (90 

percent confidence level) than 

in undisturbed old-growth 

redwood streams in Prairie 

Creek, California (Keller and 

others 1985), with our reaches 

averaging less than a third of the 

mean volume in undisturbed 

reaches. LWD accumulation 

rates since cleaning were estimated using field evidence to 

exclude any pieces left during 

cleaning. Input rates averaged 

13.7 m3/ha/yr for old growth 

and 4.2 m3/ha/yr for second 

growth. The discrepancy between old- and second-growth 

accumulation rates is primarily 

in the rate of input from the 

hillslope to the potential zone 

(defined as >0.5 m above the 

water surface and extending 1 

m laterally from the active channel). Of new LWD in the active 

channel, 41 percent (by volume) 

was associated with pools and 

65 percent (by volume) was 

trapped in debris jams.

Retrieval Terms: stream cleaning, large woody debris (LWD), 

accumulation rate, redwood 

forests, riparian, channel, debris 

jams, salmonid habitat, northern 

California (CA)

(continued from page 1)
USDA Forest Service Research Note. PSW-RN-426. 2004.

3

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

extend into privately owned second-growth redwood stands. Mill Creek is a trib-

utary to Bull Creek; Bull Creek drains into the SF Eel. HRSP acquired Mill Creek 

in 1965, and the riparian zone is second-growth redwood that was last harvested 

in the early 1950s. Weber Creek is a tributary to the main stem Eel River directly 

below the confluence of the main stem and SF Eel. Weber Creek watershed is a 

managed redwood forest owned by Pacific Lumber Company. For all study sites, 

stream cleaning began at stream mouths and proceeded upstream.

The climate of the SF Eel River is one of the wettest in California; average 

annual precipitation ranges from 140 to 280 cm/yr (period of record 1900-1980, 

Rantz 1968, Goodridge 1981). Most rainfall in the region occurs in large, frontal 

storms between November and April that produce the bulk of stream runoff. 

Snowmelt and rain on snow are minor contributors to runoff (Brown and Rit-

ter 1971). Prior to stream cleaning, the study region experienced approximately 

100-year flood events in 1955 and 1964. Based on data from Scotia (on the main 

stem Eel downstream of study sites), there were three 20- to 25-year flood events 

between cleaning and data collection: February 1986, January 1995, and January 

1997 (USGS 2002; Syvitski and Morehead 1998). The lower SF Eel is underlain by 

Franciscan greywacke sandstone deposited in deep marine environments during 

the Cretaceous (Page 1966). Slopes are steep and mantled with highly erodible 

soils in which large rotational slides are common. All study reaches are in lower 

depositional reaches of second order streams (based on USGS quad maps) where 

the gradient is ≤4 percent and elevations are ≤200 m above sea level (table 1). 

Methods

Calculation of Cleaned Reach and Sample Plot Selection

The California Conservation Corps (CCC) provided labor crews that cleaned 

the study sites in the 1980s. A CCC database provided dates of stream cleaning, 

length of cleaned reach, and a history of fish habitat improvement structures (table 2). The California Department of Fish and Game (CA DFG) surveyed all study 

streams before CCC cleaning. The CA DFG stream surveys outlined sizes and 

locations of debris jams and recommended reaches suitable for cleaning. The CCC 

database and CA DFG stream surveys were used to identify potential lengths of 

cleaned reaches for each study site. In Bridge, Fish, and Weber Creeks, potential 

lengths of cleaned reaches were shortened based on field observations of a taper-

ing off or termination of cleaning efforts. The total length of cleaned reach at each 

site was broken into 100-m-long sub-reaches, and a random sample of these was 

selected for inventory. The first 100-m sub-reaches above mainstem confluences 

were excluded from sampling due to backwater influences during high flows in 

the trunk stream. The lower 400 m of Mill Creek function as a side channel to 

Bull Creek at high flows and were also eliminated from sampling. Active chan-

nel widths were measured at the beginning, middle, and end of each sub-reach. 

Sub-reach area was calculated by multiplying the mean active channel width plus 

2 m of potential zone by the 100-m sub-reach length.

Table 1—Characteristics of five study streams, southern Humboldt County, California.

Study 

site

Legal 

description 

at confluence 

Stream 

order

Elevation 

range 

Watershed 

area 

Stream 

gradient 

in study 

reach 

Mean 

active 

channel 

width 

in study 

reaches 

Last period 

of logging 

in secondgrowth 

reaches

(T, R, S)m km

2 pct.

m

OG2nd

Bridge 2S 3E 202 50-670 6.53 6.7 5.8 late 1950s

Elk 2S 3E 212 50-610 17.42 9.6 5.8 late 1950s

Fish 3S 3E 112 60-550 11.4 2-3 8.8 8.1 late 1950s

Mill 1S 1E 252 80-590 6.5 2-3- 7.9 early 1950s

Weber 1S 2E 142 40-730 4.74- 5.6 1960s
4 USDA Forest Service Research Note. PSW-RN-426. 2004.

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

Table 2— Summary of stream cleaning history and sample size.

Study site Time between 

last cleaning and 

survey

Length of 

cleaned reach 

Sample size Total number of 

pieces measured

yr m no. of 100 m

sub-reaches

Bridge - OG 13.7 490 3 93

Elk - OG 15.6 700 3 80

Fish - OG 19.3 600 3 60

Total Old Growth - - 9 233

Bridge - 2nd 13.7 500 4 85

Elk - 2nd 15.6 2900 5 115

Fish - 2nd 19.3 600 5 160

Mill 13.6 900 6 102

Weber 16.6 500 4 293

Total Second Growth - - 24 755

Volume of Woody Debris

LWD volumes were inventoried during the summer of 1999. In each sub-reach, 

volumes were calculated for all pieces greater than 20 cm in diameter and 1.5 m 

in length. LWD was inventoried in the effective zone, defined as within the active 

channel and up to 0.5 m above the water surface (summer low flow) or channel 

bed, and in the potential zone, suspended 0.5 m or more above the channel and 

extending laterally 1 m beyond the active channel bank on both sides of the stream. 

The definitions of effective and potential zones are identical to ones used for LWD 

studies in the Caspar Creek Experimental Watershed (O’Connor and Ziemer 1989). 

The original definitions were adapted from Swanson and others (1984). Studies 

used for comparing results presented in this paper (O’Connor and Ziemer 1989, 

Keller and others 1985, Lienkaemper and Swanson 1987) define LWD as ≥10 cm 

diameter. We used a 20-cm-diameter threshold because field observations and 

anecdotal information were inconclusive as to whether the 10- to 20-cm-diameter 

range would have been targeted by stream cleaning crews. Where conditions 

permitted, diameters at both ends were recorded for pieces greater than 5 m in 

length and for shorter pieces that clearly tapered in diameter. Lengths were broken into effective and potential segments for logs occupying both zones. Lengths 

extending past the potential zone were not included. Volumes of each piece were 

calculated using Smalian’s formula for the frustum of a paraboloid: 

where D1 and D2 are the diameters at each end and L is piece length. D1 was measured above root swell for pieces with root wads and at the largest measurable 

diameter for pieces without. When only one diameter was measured this value 

was used for D1 and D2. Volumes were calculated separately for irregular root 

wads without trunks. These volumes were calculated as a product of length, 

width, and height, and a percent pore space was estimated and deducted from 

root portions with an open framework.

Accumulation Rates

Decay classes were assigned for each piece according to a classification system 

adapted from Maser and Trappe (1984) (table 3). All measured pieces were assigned 

a pre- or post- stream-cleaning age class according to guidelines in table 4.

Accumulation rates were derived for each sub-reach by combining “new” and 

“probably new” wood and dividing by the number of years between final stream 

cleaning and the 1999 LWD inventory.

Volume = π(D1

2+D22)L

8 (1)

Accumulation Rate = (new + prob new wood(m (2) 3)) =

(sub-reach area (ha)) (yrs post cleaning)

m3/ha/yr
USDA Forest Service Research Note. PSW-RN-426. 2004. 5

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

Table 3— A five-class system of evaluating decay of coniferous woody debris (Maser and Trappe 1984).

Decay Class Bark Twigs Texture Shape Wood color

I Intact Present Intact Round Original color

II Intact Absent Intact Round Original color

III Trace Absent Smooth, some 

surface abrasion Round Original color, darkening

IV Absent Absent

Abrasion, 

some holes and 

openings

Round to oval Dark

V Absent Absent

Vesicular, many 

holes and 

openings

Irregular Dark

Table 4— Chronological classification criteria.

Classification Criteria

Old • Bucked ends and keyed into banks perpendicular to flow, usually bucked at 

active channel margin

• Trapped in jams under bucked pieces or in a position deposited prior to bucked 

logs

• Jam pieces with burn scars resulting from fires set by crews to remove jams

• Pieces identified in Department of Fish and Game stream surveys prior to 

stream cleaning

• Deeply embedded and deformed due to constant fluvial erosion: usually very 

large amorphous redwood pieces with minimal surface area exposed and fluvially incised grooves on surface, not in danger of causing a jam, and nearly 

impossible to remove

Probably Old • Decayed logs (≥IV decay class) that added bank stability, were oriented parallel 

to flow, were deeply keyed into banks, caused minimal threat of jam formation 

and would have been difficult to remove

• Trapped in jams with old pieces in a manner suggesting similar depositional 

time, usually in the internal structure of a debris jam showing evidence of 

cleaning 

• Hillslope delivered logs that were ≥IV decay class, posed no threat of forming 

a jam, and were out of the active channel

• Pieces with sprouts, alders, or other vegetative indicators that were established 

post LWD deposition and were >20 years old

• Decayed logs (≥IV decay class) that would have been inaccessible to hand 

crews

New • Pieces with recent mechanism for input such as fresh slides or bank collapse

• Minimally decayed logs oriented perpendicular to flow that had potential for 

trapping other debris and would have been easily removed by hand crews

• Logs with needles or leaves still intact (decay class I) and decay class II unless 

contradictory evidence was present

• Fluvially deposited pieces trapped on upstream side of pieces meeting “new” 

criteria defined above

Probably New • Logs trapped in debris jams with new pieces and oriented in a position that 

suggests deposition after that of “new” pieces

• Logs deposited near logs showing evidence of cleaning in an orientation/

location that would have merited removal which were easily accessible by 

hand crews

• Debris jams without distinct old or new evidence that are not identified by 

Department of Fish and Game stream surveys, are in reaches with other cleaned 

pieces, and would have been easily removed

• Hillslope delivered pieces with minimal weathering or revegetation of root 

throw pits
6 USDA Forest Service Research Note. PSW-RN-426. 2004.

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

Debris Delivery 

A delivery mechanism was assigned for individual LWD pieces in order to as-

sess predominant debris sources. Debris sources were broken into “hillslope” or 

“fluvial.” 

Direct hillslope inputs included bank erosion, landslides, and windthrow. 

Additional hillslope evidence included pieces with rootwads upslope and broken 

segments that could be linked with related pieces on the hillside. Fluvial pieces 

have been mobilized from their original channel deposition site and have no 

evident hillslope link. Although wind fragmented pieces may be in their origi-

nal location, their upslope origin is difficult to identify. Such pieces were likely 

labeled as fluvial. 

Additional Data

We noted whether pieces were associated with debris jams. A debris jam was 

defined as an aggregation of three or more pieces satisfying the LWD criteria. 

Each piece within a debris jam was measured. Tree species were also recorded. 

Redwood and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were the only 

species found in substantial quantity. Other species identified were bigleaf maple (Acer macrophyllum Pursh), tanoak (Lithocarpus densiflorus (Hook. & Arn.) Rehd.), 

madrone (Arbutus menziesii Pursh), and red alder (Alnus rubra Bong.). LWD that 

could not be identified was classified as coniferous, hardwood, or unknown. LWD 

that was associated with pools was also noted. Pool association was defined by 

presence of LWD in the effective zone in or adjacent to a pool. Pools were defined 

and classified as main, backwater, scour, or plunge according to a scheme adapted 

from Bisson and others (1987).

Analysis

We looked for differences in wood volumes, inputs, and accumulation rates be-

tween old-growth and second-growth reaches. Mean and total values of each 

variable for each stand condition (old- or second-growth) were calculated us-

ing stratified sampling estimators (Cochran 1977). For example, the total LWD 

volume/ha in old-growth reaches was estimated as: 

where c is an old-growth creek reach, Vc is the mean total volume/ha for all 

sub-reaches in that reach, N

c is the number of 100-meter sub-reaches in the 

reach (sampled and unsampled), and N is the total number of sub-reaches in all 

old-growth reaches. Satterthwaite’s (1946) procedure for estimating variances 

and degrees of freedom was used to calculate confidence intervals and perform 

t-tests. 

Results

LWD Characteristics

The frequency distributions of LWD tree species remained relatively consistent 

between old- and second-growth reaches (fig. 2). The decrease of redwood LWD 

in second growth may be partially attributed to the increase in pieces classified as 

unknown and conifer spp. but could also reflect differences in stand composition. 

Figure 2 also shows similar percent frequency distributions for chronological clas-

sifications of LWD for old- and second-growth reaches. The high frequency of old 

LWD in both reach types appears to indicate that stream cleaning was not thor-

ough. However, a significant percentage of the old LWD category are remnants of 

modified jams or are logs cut during stream cleaning at or near channel margins 

that now extend into the present potential zone. The higher frequency of "old" 

than "new" pieces indicates that fewer pieces have accumulated since cleaning 

VolumeOG = 

∑c

N

c

Vc

N

(3)
USDA Forest Service Research Note. PSW-RN-426. 2004. 7

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

Table 5— Comparison of new and old LWD (Large Woody Debris) pieces in old-growth and second-growth 

reaches.

Pre/post stream cleaning New LWD Old LWD

Reach type Old G 2nd Combined Old G 2nd Combined

Number of pieces measured 64 263 327 169 492 661

Pct. trapped by jams (pct. of pieces) 48 73 68 42 53 50

(pct. of vol.) 57 74 65 54 61 58

Pct. hillslope delivered (pct. of pieces) 52 59 57 50 55 53

(pct. of vol.) 93 76 85 71 70 70

Pct. in effective zone that is 

pool associated (pct. of pieces) 20 28 26 25 20 21

(pct. of vol.) 34 44 41 49 31 39

Average large end diameter m 0.51 0.35 0.38 0.60 0.48 0.51

Average length m 6.8 6.0 6.2 4.5 3.5 3.8

Average volume m3 3.4 0.7 1.3 1.9 0.9 1.2

than were present before cleaning. Since our "old" counts do not include pieces 

that were completely removed, the actual ratio of pre-cleaning to recently-added 

pieces is probably much higher.

Roughly two-thirds (68 percent) of newly recruited LWD was found in debris 

jams (table 5). Fifty percent of old LWD was found in jams, which is a higher frequency than expected if cleaning crews targeted debris jams. However, most old 

LWD found in jams were remains of large debris structures in the potential zone 

where in-channel segments had been removed. Approximately 50-60 percent of 

LWD pieces in all categories appeared to be hillslope delivered; hillslope inputs 

accounted for the majority of the volume in all categories (85 percent of new and 

70 percent of old volume.) About a quarter of all pieces in the effective zone were 

pool associated, and approximately 40 percent of the effective zone volume was 

associated with pools. 

Table 5 also summarizes sizes and volumes of new and old LWD. Lengths and 

volumes for old LWD are likely to be smaller than before stream cleaning because 

many old pieces were partially removed, although diameters may reflect original 

values. Average large-end diameter is greater in old-growth reaches, and new 

pieces have smaller diameters than old pieces in both second-growth and oldgrowth reaches. The smaller diameter for new pieces in both reach types may 

reflect conversion from old- to second-growth stands and a slower decay rate for 

large pieces of old LWD. Old-growth fluvial inputs may reflect upstream, nonold-growth watershed conditions due to the short length (<800 m) of old-growth 

Figure 2—Percent frequency distribution of LWD (Large Woody Debris) 

tree species and frequency distribution 

of LWD chronological classifications for 

three old-growth and five second-growth 

study sites.
8 USDA Forest Service Research Note. PSW-RN-426. 2004.

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

reaches in this study. New pieces tended to be longer than old pieces in both reach 

types. The shortness of old pieces is likely a result of stream cleaning and increasing fragmentation and splintering with time. New LWD in old-growth reaches 

has the highest average piece volume, largely as a result of three hillslope-derived 

pieces averaging 36.6 m3. Excluding these pieces drops the mean new piece volume in old-growth reaches from 3.4 to 1.7 m3.

LWD Volume and Accumulation Rates 

Weighted mean volumes and accumulation rates in old-growth reaches were 

over twice those in second-growth reaches (135 percent and 245 percent greater, 

respectively). Total volumes of woody debris in old-growth channels averaged 589 

m3/ha and ranged from 100 to 1063 m3/ha for nine sub-reaches in three creeks, 

while second-growth channels averaged 251 m3/ha and ranged from 30 to 1044 

m3/ha for 24 sub-reaches in five channels (table 6). A t-hypothesis test showed 

old-growth volumes were significantly greater than second-growth at a 90 percent 

confidence level, with a confidence interval on the mean difference of 168-509 

m3/ha. Accumulation rates in old-growth reaches averaged 13.7 m3/ha/yr and 

ranged from 0.1 to 37.5 m3/ha/yr. Second-growth channels averaged 4.2 m3/ha/

yr and ranged from 0 to 24.4 m3/ha/yr. The confidence interval on the mean difference (0.01-19.1 m3/ha/yr) indicates that old-growth accumulation rates were 

significantly higher than those in second-growth reaches. 

Although we believe that we did identify most pieces not removed by crews, 

there was an element of subjectivity in determining whether LWD was deposited 

post-cleaning (“new”) or pre-cleaning (“old”). Assigning “new” or “old” status 

to LWD is essential for estimating accumulation rates. The “probably old” and 

“probably new” categories have the highest potential for error; only LWD with 

definitive evidence were included in the “new” and “old” categories. All accumulation rates presented in this study are calculated based on “new” and “probably 

new” categories. A reasonable approximation for maximum potential error would 

be to either include “probably old” or exclude “probably new” from accumulation 

rates. By including all “probably old” LWD, accumulation rates were 21.1 m3/

ha/yr and 6.4 m3/ha/yr for old and second growth, respectively. By excluding all 

“probably new” LWD, accumulation rates were 7.0 m3/ha/yr and 3.3 m3/ha/yr 

Table 6—Volumes by zone, accumulation rates, and residence times for three old-growth and five second-growth study sites. Values 

are means ± the standard error of the mean (group means are weighted). Residence times are based on mean accumulation rates.

Study Site Total LWD 

volume

Potential 

zone volume

Effective 

zone volume

Volume of 

new wood

Accumulation 

Rate

Residence 

Time

m3 / ha m3 / ha m3 / ha m3 / ha m3 / ha / yr yr

Bridge - OG 562 ± 99 392 ± 204 220 ± 40 96 ± 46 7.0 ± 3.4 80

Elk - OG 723 ± 204 615 ± 214 130 ± 23 236 ± 178 15.1 ± 11.4 47

Fish - OG1 455 ± 190 424 ± 183 40 ± 18 339 ± 170 17.6 ± 8.8 26

Mean Old Growth 589 ± 82 490 ± 84 125 ± 11 232 ± 67 13.7 ± 4 43

Bridge - 2nd 216 ± 64 148 ± 52 95 ± 31 38 ± 24 2.7 ± 1.8 80

Elk - 2nd 183 ± 56 108 ± 39 102 ± 26 37 ± 14 2.3 ± 0.9 80

Fish - 2nd 355 ± 139 314 ± 126 51 ± 20 112 ± 59 5.8 ± 3.0 61

Mill 139 ± 56 104 ± 44 45 ± 20 50 ± 17 3.7 ± 1.2 38

Weber 758 ± 225 607 ± 181 205 ± 63 253 ± 96 15.2 ± 5.8 50

Mean Second Growth 251 ± 30 180 ± 22 96 ± 13 67 ± 8 4.2 ± 0.5 60

1In sub-reach 3 of Fish OG there was an unmeasurable jam not included in calculated volumes. The jam formed a 5-m-tall vertical 

step in the channel profile, and sediment was completely aggraded to the top of the jam. Only one side of the jam was exposed, and piece 

lengths were undeterminable. The jam was entirely old wood; there were buck and burn marks throughout, and the jam was clearly 

outlined in California Department of Fish and Game surveys. The jam had no exposed upstream side to trap new wood. The total space 

occupied by the jam was estimated at 340 m3; percent wood was not available.
USDA Forest Service Research Note. PSW-RN-426. 2004. 9

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

for old and second growth, respectively. In all cases, accumulation rates are higher 

in old- than in second growth, indicating that the general pattern we observed is 

not affected by misclassification of individual pieces.

The mean residence times of LWD in both reach types were similar to oldgrowth Douglas-fir forests in Oregon (Lienkaemper and Swanson, 1987). The 

residence or turnover time of woody debris can be calculated by dividing the 

total volume of wood by the accumulation rate. A residence time assumes the 

inputs and outputs have reached equilibrium, an unlikely premise considering the 

impacts of stream cleaning and the high spatial and temporal variability in LWD 

inputs. Assuming that wood volumes are below equilibrium due to cleaning, and 

that accumulation rates are reasonable, the residence times calculated would represent minimum estimates. The mean residence time was 43 years in old growth 

and 60 years in second growth, ranging from 26 to 80 years for all study reaches. 

These estimates may contain unknown errors propagated in the accumulation 

rates due to a small number of samples, small observation periods relative to 

redwood decay rates, and potential mislabeling of LWD age. Lienkaemper and 

Swanson (1987) reported an average turnover time of 50 years, ranging from 12 

to 83, for five streams in old-growth Douglas-fir forests in H. J. Andrews Experimental Forest, Oregon. Their accumulation rates were similar to our old-growth 

rates, averaging 11.8 m3/ha/yr and ranging from 5 to 20 m3/ha/yr.

Data from this study indicate that these old-growth reaches accumulate LWD 

volume faster than second-growth reaches due to a higher hillslope delivery rate 

Table 8— Effective and potential zone accumulation rates and percent hillslope contribution for three old-growth 

and five second-growth study sites. Site values are means ± one standard deviation. Values are means ± the 

standard error of the mean (group means are weighted).

Study site Potential zone 

accumulation 

rate

Proportion of 

new potential 

from hillslope

Effective zone 

accumulation 

rate

Proportion of 

new effective 

from hillslope

m3 / ha / yr pct. by volume m3 / ha / yr pct. by volume

Bridge - OG 5.9 ± 3.1 98 1.4 ± 1.4 96

Elk - OG 14.7 ± 11.5 90 0.6 ± 0.5 7

Fish - OG 17.2 ± 8.7 97 0.4 ± 0.2 29

Mean Old Growth 13.1 ± 4.0 94 0.8 ± 0.3 48

Bridge - 2nd 2.6 ± 1.6 57 0.3 ± 0.2 20

Elk - 2nd 1.4 ± 0.5 70 1.3 ± 0.8 43

Fish - 2nd 5.6 ± 2.9 91 0.3 ± 0.2 47

Mill 2.8 ± 0.8 64 1.2 ± 0.7 33

Weber 14.2 ± 5.5 83 1.4 ± 0.5 48

Mean Second Growth 3.4 ± 0.4 78 1.1 ± 0.4 41

Table 7— Hillslope and fluvial accumulation rates in three old-growth and five second-growth study sites. 

Values are means ± the standard error of the mean (group means are weighted). 

Study Site Hillslope accumulation rate

m3 / ha / yr

Fluvial Accumulation rate

m3 / ha / yr

Bridge - OG 6.8 ± 3.4 0.2 ± 0.1

Elk - OG 13.2 ± 12.1 1.9 ± 1.8

Fish - OG 16.8 ± 8.7 0.8 ± 0.2

Mean Old Growth 12.7 ± 4.2 1.1 ± 0.6

Bridge - 2nd 1.5 ± 0.7 1.2 ± 1.1

Elk - 2nd 1.4 ± 0.6 1.0 ± 0.5

Fish - 2nd 5.1 ± 2.6 0.7 ± 0.4

Mill 2.1 ± 1.0 1.6 ± 1.0

Weber 12.2 ± 5.0 3.0 ± 1.4

Mean Second Growth 2.9 ± 0.4 1.3 ± 0.3
1

0 USDA Forest Service Research Note. PSW-RN-426. 2004.

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

to the potential zone. Accumulation rates from hillslope sources averaged 9.7 m3/ha/yr (333 percent) higher in old-growth reaches than in second-growth 

reaches, with a 90 percent confidence interval of -0.1 to 19.6 m

3/ha/yr (table 7). 

This difference was not evenly distributed between the effective and potential 

zones. Hillslope inputs to the potential zone averaged 12.3 m

3/ha/yr and 2.6 

m

3/ha/yr in old- and second- growth reaches, respectively, but hillslope inputs to 

the effective zone averaged 0.4 m

3/ha/yr in both old- and second-growth stands. 

Hillslope inputs have a greater impact in the potential zone in part because a large 

percentage of hillslope recruits span the channel (>0.5 m above active channel) 

and do not come into contact with the effective zone. The old-growth hillslope 

accumulation estimates seem consistent with reported mean forest floor input 

rates in old-growth Douglas-fir forests in Oregon and Washington that ranged 

from 11.2 to 17.5 m

3/ha/yr (Grier and Logan 1977, Sollins 1982). Grier and Logan 

(1977) and Sollins (1982) defined LWD as pieces greater than 10 cm in diameter, 

and a 400 kg/m

3 conversion was used to compare results.

Mean accumulation rates for fluvially transported LWD in old- and secondgrowth reaches show no significant difference (confidence interval -1.7 to 1.3 m3/ha/yr). The old-growth riparian zones examined here extend a short distance 

from the bottom of their respective watersheds. Thus the majority of contributing 

watershed upstream of old-growth reaches was second growth, which may explain 

a lack of statistical difference between reach types for fluvial inputs. Fluvial input 

rates for old-growth sub-reaches did not increase as length of upstream old-growth 

riparian zone increased. The maximum extent of old-growth riparian forest 

upstream of any of the study reaches was 400 meters, for sub-reach 1 in Elk Creek. 

The fluvial accumulation rate in sub-reach 1, Elk Creek, was 0.1 m

3/ha/yr, which 

was the lowest for any of the old-growth reaches sampled in this study. It appears 

that the relatively short length (≤400 m) of old-growth riparian zones upstream 

of our study sub-reaches was not enough to produce fluvial accumulation rates 

indicative of old-growth watersheds at our study sites. Additionally, the fluvial 

accumulation rate of old-growth watersheds may be small due to low mobility of 

large pieces from old-growth hillslopes. Longer time spans than those covered in 

this study, encompassing large, infrequent storms, may be required to properly 

evaluate old-growth fluvial inputs and piece mobility. 

For all study reaches the potential zone accumulates LWD at a faster rate than 

the effective zone (table 8). The potential zones in old-growth reaches accumulate 

LWD faster than those in second growth; however, effective zones in old growth 

and second growth accumulate at similar rates. The potential zone accumulates 

an average of 13.1 m

3/ha/yr in old growth and 3.4 m3/ha/yr in second growth 

(table 8). Our estimated confidence interval on this mean difference (9.5 m

3/ha/yr) 

is 0.2-19.2 m

3/ha/yr. In the potential zone, most of the accumulated wood (95 

percent by volume in old growth and 78 percent in second growth) came from 

hillslopes. The effective zone accumulated wood at an average of 0.8 m

3/ha/yr 

in old-growth reaches and 1.1 m

3/ha/yr in second-growth reaches. These rates 

were not significantly different. Hillslope inputs were less important in the ef-

fective zone, contributing 48 percent of the new wood in this zone in old-growth 

reaches and 41 percent in second-growth reaches. The observed difference be-

tween old- and second-growth reach types in the potential but not the effective 

zone can be attributed partly to the large volume of hillslope inputs spanning 

the channel within the potential zone that do not reach the effective zone in oldgrowth reaches.

Discussion

Harmon and others (1986) refer to LWD as a regularly neglected ecosystem compo-

nent due to sampling difficulties attributed to its inherent wide variations in space 

and time. The high standard deviations in LWD volumes and accumulation rates 

in this study attest to the dynamic nature of LWD. A “feast or famine” pattern was 

often evident among contiguous reaches; three adjacent old-growth reaches in Fish 
USDA Forest Service Research Note. PSW-RN-426. 2004.

11

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

Creek had respective volumes of 519, 100, and 747 m

3/ha and accumulation rates 

of 22.6, 0.4, and 29.7 m

3/ha/yr. Lienkaemper and Swanson (1987) reported that 

one or two trees dominated the volume of debris delivered in a 7 to 9 year obser-

vation period, and in one watershed (#9) a single tree accounted for 75 percent of 

all wood delivered over 8 years. 

Geomorphic and hydrologic variations between study sites were minor due to 

similar locations within watersheds and within the region. Watershed area ranged 

from 4.7 to 17.4 km

2. Typically, a larger watershed produces a wider active chan

-

nel, and wider channels tend to retain fewer LWD pieces due to increased piece 

mobility (Bilby and Ward 1989; Lienkaemper and Swanson 1987). However, larger 

channels tend to retain pieces with greater volumes and have a higher percentage 

of LWD associated with the effective zone (Bilby and Ward 1989; Robison and 

Beschta 1990). All of our study sites are second order channels, and gradient and 

active channel widths are relatively similar between streams, which may explain 

the lack of an obvious effect of watershed area in LWD volumes and accumula-

tion rates. 

The efficacy of the CCC stream cleaning crews is an important component 

of the accumulation rates presented in this study. Based on conversations with 

CA DFG and CCC personnel, we concluded that stream cleaning before 1986 was 

thorough. Evidence of stream cleaning was prevalent throughout study reaches, 

suggesting cleaning crews indeed treated the entire study reach. However, the 

level of wood removal may have varied somewhat between crews and crew lead-

ers. Our classification of unremoved pieces as “old” or “probably old” should 

have prevented differences between crews from affecting our accumulation rates, 

if our classifications were accurate. Since large wood and debris jams were more 

likely removed because of greater potential for forming barriers, older LWD that 

were mislabeled as “new” or “probably new” are presumed low in number and 

likely to have relatively small volumes. Our analysis of the effects of misclassify-

ing LWD depositional age class on accumulation rates further indicates that any 

likely errors would not affect our conclusion that accumulation rates are higher 

in old than in second growth.

An objective of the study was to quantify and assess the current woody debris 

loads in cleaned streams with no installed instream structures. The mean oldgrowth volume of 589 m3/ha for cleaned reaches is significantly less (p-value 

= 0.04) than the mean value of 1950 m

3/ha reported by Keller and others (1985) 

for seven reaches in second-order undisturbed redwood-dominated streams 

in Prairie Creek, California. Keller and others (1985) included the 10 to 20 cm 

diameter range in their volumes, which was not included in this study. Although 

frequency may be high, the proportion of total volume in the 10- to 20-cm diameter 

range is assumed to be small. LWD in the 10- to 20-cm diameter range in a 1998 

woody debris inventory in Redwood Creek, California, accounted for <1 percent 

of the total wood volume for a 7,215-m study reach in which 2,818 pieces were 

measured (Kramer and Klein 1999). Control populations for uncleaned but logged 

second order redwood streams have not been identified. The mean second-growth 

volume of 251 m

3/ha for cleaned reaches was slightly lower than the mean value 

of 339 m

3/ha reported for the North Fork Caspar Creek (NFC) (O’Connor and 

Ziemer 1989). The NFC is a managed second-growth forest that was effectively 

Table 9— Estimated LWD accumulation rates (m

3 / ha / yr) for potential and effective zones in the North (NFC) 

and South (SFC ) Forks Caspar Creek, Jackson Demonstration State Forest, California (Keppeler 1996) .

Stream Data Source Accumulation 

period

Last Logging Accumulation rate m3 / ha / yr 

NFC O’Connor and Ziemer 1989 1926-1986 about 1900 5.3

NFC Keppeler, 1996 1926-1996 1989-1991 6.3

NFC Surfleet and Ziemer 1996 1986-1994 1989-1991 7.5

NFC Keppeler, 1996 1994-1996 1989-1991 32.6

SFC Keppeler, 1996 1994-1996 1971-1973 13.6
1

2 USDA Forest Service Research Note. PSW-RN-426. 2004.

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

cleaned during logging 90 to 100 years before O’Connor and Ziemer’s LWD 

inventory. Although the NFC is predominantly second-growth redwood, LWD 

were primarily Douglas-fir and grand fir (Abies grandis) due to their shorter life 

cycles (O’Connor and Ziemer 1989). LWD species distributions in second-growth 

reaches noted in this study do not follow patterns observed in NFC, possibly 

because Douglas-firs that were established after logging have yet to reach maturity 

in the shorter time period following harvest.

Table 9 lists LWD accumulation rates for Caspar Creek calculated by Keppeler 

(1996), including data from Surfleet and Ziemer (1996), and O’Connor and Ziemer 

(1989). The revised long-term accumulation rate of 6.3 m

3/ha/yr for the NFC 

site is less than the old-growth and slightly greater than the second-growth mean 

accumulation rates presented in this study. The NFC site was an approximately 

100-year-old second-growth redwood forest before logging, with selectively 

logged buffers, in 1989. Therefore, one would expect the NFC accumulation rate 

to lie between the rates for old-growth and second-growth reaches logged in the 

1950s and 1960s presented in this study. The NFC accumulation rate may be closer 

to our second-growth rates partly because the Douglas-fir and grand fir that made 

up most of that volume were not as large as the old-growth redwoods that con-

tributed wood to our old-growth study sites. As previously outlined, old-growth 

accumulation rates in this study probably reflect old-growth hillslope inputs and 

second-growth fluvial inputs. The effect of second-growth fluvial inputs on oldgrowth accumulation rates is unclear because pieces derived from second-growth 

forests have lower volumes but higher mobility.

Weber Creek has a considerably larger LWD accumulation rate and volume 

than the other second-growth reaches in our study. The riparian zone in Weber 

Creek was last logged in the 1960s, and this site has the highest mean total volume 

of LWD and the second highest accumulation rate. Large flow events in 1995 and 

1997 appear to have caused massive bank erosion and failures on both sides of the 

channel above sub-reach 1 (200 m above mouth). Hillslope failures extended 6 to 

20 m upslope and delivered as many as 37 redwoods to the channel in sub-reach 3. 

Assuming trees derived from the hillslope with decay class I or II were delivered 

during the 1995 event, the average input rate for LWD in the three sub-reaches 

above sub-reach 1 was 60.6 ± 41.1 m

3/ha/yr from 1995 to 1999. Keppeler (1996) 

also notes a high input rate of 32.6 m

3/ha/yr for the NFC following post-logging 

windstorms (table 9). Though the effects of large inputs are attenuated over time, 

they create extreme spatial and temporal variability in LWD accumulation, and 

their effects must be evaluated over long time periods. Bisson and others (1987) 

suggest that periods <25 years are subject to episodic swings in LWD trends.

Conclusion

Approximately 14 to 19 years following stream cleaning, the volumes of woody 

debris in cleaned old-growth redwood reaches were significantly less than those 

in uncleaned reaches. Old-growth reaches were found to accumulate LWD at a 

faster rate than second-growth reaches; however, the difference in input rates ap-

pears in the potential but not the effective zone. The old-growth accumulation 

rate, 13.7 m

3/ha/yr, is derived from old-growth hillslope inputs and primar

-

ily second-growth fluvial inputs since the majority of upstream riparian zones 

are second growth. Hillslope-derived LWD accumulates more quickly in oldgrowth reaches, 12.7 m3/ha/yr compared to 2.9 m3/ha/yr for second growth. 

Hillslope-derived LWD contributes >75 percent of the new volume in old- and 

second-growth potential zones. The mean accumulation rate in the effective zone 

was <2 m

3/ha/yr in both old-growth and second-growth reaches, and more than 

half of that wood was fluvially-derived in both reach types. The significance of 

upstream LWD inputs is emphasized by the substantial fluvial contribution to 

the effective zone. Rates observed in this study suggest that streams with a 40- to 

50-year-old second-growth riparian zone accumulate LWD at about 50 percent of 
USDA Forest Service Research Note. PSW-RN-426. 2004.

13

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

the rates characteristic of stream reaches bordered by old-growth redwood forest. 

The higher accumulation rates in old growth versus developed second growth are 

consistent with Murphy and Koski’s (1989) modeling results that predict LWD in 

previously undisturbed streams will decline over time after logging due to the 

decreased supply of debris provided by second-growth forests. If instream LWD 

loading is to be maintained at pre-logging levels, forest management practices will 

need to ensure that sufficient steps are taken to compensate for decreased LWD 

accumulation rates following harvest. Due to the high spatial and temporal vari-

ability in LWD noted in this study and others, additional long-term studies would 

be useful to better understand and quantify the dynamic aspects of LWD. 

Acknowledgments

Randy Klein, Redwood National Park, and Matt O’Connor, O’Connor Environ-

mental Consulting, provided insightful peer reviews that greatly improved the 

content of the manuscript. Redwood Sciences Laboratory (RSL) of the Pacific 

Southwest Research Station, USDA Forest Service, and Americorps Watershed 

Stewards Project, Fortuna, California, provided funding, equipment, and field 

assistants. Field assistants Tom Grey and Sherman Garinger are gratefully ac-

knowledged for crawling through many debris piles. Diane Sutherland of RSL 

provided the study site map. California State Parks granted permission to access 

Humboldt Redwoods State Park property. Ruth Goodfield of Eel River Watershed 

Improvement Group and Scott Downie, California Department of Fish and Game 

(DFG), facilitated private landowner access. DFG personnel Gary Flossi, Carl 

Harral, Larry Preston, and John Schawbe provided historical data and anecdotal 

information. Tom Lisle and Leslie Reid of RSL provided the catalyst for the project 

and guidance throughout.

References

Andrus, Chip W.; Long, Barry A.; Froehlich, Henry A. 1988. Woody debris and its contribu-

tion to pool formation in a coastal stream 50 years after logging. Canadian Journal of 

Fisheries and Aquatic Sciences 45: 2080-2086.

Bilby, Robert E.; Ward, James W. 1989. Changes in characteristics and function of woody 

debris with increasing size of streams in western Washington. Transactions of the Ameri-

can Fisheries Society 118: 368-378.

Bilby, Robert E; Likens, Gene E. 1980. Importance of organic debris dams in the structure 

and function of stream ecosystems. Ecology 61: 1107-1113.

Bisson, Peter A.; Bilby, Robert E.; Bryant, Mason D.; and others. 1987. Large woody debris 

in forested streams in the Pacific Northwest: Past, present, and future. In: Salo, E.O.; 

Cundy, T., eds. Streamside management: Forestry and fisheries interactions. Seattle: 

University of Washington Press; 143-190.

Brown, William M. III; Ritter, John R. 1971. Sediment transport and turbidity in the Eel River 

basin, California. U.S. Geological Survey Water-Supply Paper 1986: 5-16.

California Resources Agency. 1982. Investing for prosperity: Enhancing resources to meet 

human and economic needs: An update. Sacramento: Calif. Resources Agency; 45 p. 

Cochran, William G. 1977. Sampling techniques. Third edition. New York: John Wiley.

Goodridge, James D. 1981. California rainfall summary: Monthly precipitation, 1849-1980.

Sacramento: California Resources Agency, Department of Water Resources; 43 p.

Grier, Charles C.; Logan, Robert S. 1977. Old-growth Pseudotsuga menziesii communities 

of a western Oregon watershed: Biomass distribution and production budgets. Ecologi-

cal Monographs 47: 373-409.

Harmon, Mark E.; Franklin, Jerry F.; Swanson, Fredrick J.; and others. 1986. Ecology of 

coarse woody debris in temperate ecosystems. In: MacFadyen, A.; Ford, E.D., eds. Ad-

vances in ecological research 15. New York: Harcourt Brace Jovanovich; 133-302.

Keller, Edward A.; MacDonald, Anne; Tally, Taz; and others. 1985. Effects of large debris 

on channel morphology and sediment storage in selected tributaries of Redwood Creek, 

northwestern California. In: Nolan, K.M.; Kelsey, H.M.; Maron, D.C., eds. Geomorphic 

processes and aquatic habitat in the Redwood Creek basin, northwestern California. U.S. 

Geological Survey Professional Paper 1454.
14 USDA Forest Service Research Note. PSW-RN-426. 2004.

 Large Woody Debris Volumes and Accumulation Rates in Cleaned Streams in Redwood Forests 

 Southern Humboldt County, California

Keppeler, Elizabeth T. 1996. Caspar Creek large organic debris revisited. Unpublished report. Redwood Sciences Laboratory, Pacific Southwest Research Station, Forest Service, 

U.S. Department of Agriculture, Arcata, CA.

Kramer, Sharon; Klein, Randy D. 1999. The distribution and role of large woody debris in 

upper Prairie Creek, a pristine northern California redwood watershed. Presented at 

Wildlife Society western section meeting, Nov. 1999. Reno, Nevada.

Lienkaemper, George W.; Swanson, Fredrick J. 1987. Dynamics of large woody debris in 

streams in old-growth Douglas-fir forests. Canadian Journal of Fisheries and Aquatic 

Sciences 17: 150-156.

Maser, Chris; Trappe, James M. 1984. The seen and unseen world of the fallen tree. USDA 

Forest Service Gen. Tech. Rep. PNW-164. Portland, OR: Pacific Northwest Research Station, Forest Service, U.S. Department of Agriculture; 56 p.

Murphy, Michael L.; Koski, K V. 1989. Input and depletion of woody debris in Alaska 

streams and implications for streamside management. North American Journal of Fisheries Management 9: 427-436.

O’Connor, Matthew D.; Ziemer, Robert R. 1989. Coarse woody debris in a second-growth 

Sequoia sempervirens forest stream. Proceedings of the California riparian systems conference. USDA Forest Service Gen. Tech. Rep. PSW-110. Berkeley, CA: Pacific Southwest 

Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture; 

165-171.

Page, Ben M. 1966. Geology of the Coast Ranges of California, In; Bailey, E.H. Geology of 

Northern California, Bulletin 190, California Division of Mines and Geology; 253-321.

Rantz, S.E. 1968. Average annual precipitation and runoff in north coastal California. USGS 

Hydrologic Inventory. Atlas HA-298.

Robison, E. George; Beschta, Robert L. 1990. Characteristics of coarse woody debris for 

several coastal streams of southeast Alaska, USA. Canadian Journal of Fisheries and 

Aquatic Sciences 47: 1684-1693.

Satterthwaite, F.E. 1946. An approximate distribution of estimates of variance components.

Biometrics 2: 110-114.

Sollins, Phillip. 1982. Input and decay of coarse woody debris in coniferous stands in western Oregon and Washington. Canadian Journal of Forest Research 12: 18-28.

Swanson, Fredrick J.; Bryant, Mason D.; Lienkaemper, George W.; and others. 1984. Organic 

debris in small streams, Prince of Wales Island, southeast Alaska. USDA Forest Service 

Gen. Tech. Rep. PNW-166. Portland, OR: Pacific Northwest Research Station, Forest 

Service, U.S. Department of Agriculture.

Surfleet, Christopher G.; Ziemer, Robert R. 1996. Effects of forest harvesting on large organic 

debris in coastal streams. Proceedings of the conference on coast redwood forest ecology 

and management; Humboldt State University, Arcata, CA: 134-136.

Syvitski, James P.; Morehead, Mark D. 1998. Estimating river-sediment discharge to the 

ocean: Application to the Eel margin, northern California. Marine Geology 154: 29-41.

USGS. 2002. Surface water for USA: Peak streamflow. Eel River at Scotia, 1/20/1911 to 3/5/

2001. URL: http://waterdata.usgs.gov/nwis/peak/?site_no=11477000. U.S. Geological 

Survey, Reston, Virginia. (Last accessed Jan. 21, 2003)

The Authors

John Wooster is a geomorphologist at Stillwater Sciences, 2855 Telegraph Ave. 

Suite 400, Berkeley, CA 94705; email address: wooster@stillwatersci.com. 

Sue Hilton is a hydrologist at the Redwood Sciences Laboratory, Pacific Southwest Research Station, USDA Forest Service, 1700 Bayview, Arcata, CA 95521

The U.S. Department of 

A g r i c u l t u r e p r o h i b i t s 

discrimination in its programs and activities on the 

basis of race, color, national 

origin, sex, religion, age, 

disability, political beliefs, 

sexual orientation or marital 

or family status. (Not all 

prohibited bases apply to 

all programs.) Persons with 

disabilities who require 

alternative means for communications of program 

information (braille, large 

print, audiotape, etc.) should 

contact the USDA's TARGET 

Center at (202) 720-2660 

(voice and TDD). To file a 

complaint of discrimination, 

write USDA, Director of 

Civil Rights, Room 326-W. 

Whitten Building, 14th/. 

and Independence Avenue, 

SW, Washington, DC 20250-

9410 or call 1-866-632-9992 

(voice). USDA is an equal 

employment opportunity 

employer.

Federal Recycling Program

Printed on Recycled Paper