PACIFIC SOUTHWEST 

FOREST SERVICE. 

U. S. DEPARTMENT OF AGRICULTURE 

P.O. BOX 245, BERKELEY, CALIFORNIA 94701 

Forest and Range 

Experiment Station 

ROAD CONSTRUCTION ON 

CASPAR CREEK WATERSHEDS... 

10-year report on impact 

J. S. Krammes David M. Burns 

USDA FOREST SERVICE RESEARCH PAPER PSW- 93 /1973 
CONTENTS 

Page

 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

 Soils and Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

 Treatments and Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

 Silvicultural Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

 Road Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

 Streamflow and Sedimentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

 Erosion and Landslides . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 5 

 Stream Turbidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

 Suspended Sediment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

 Debris Basin Deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

 Aquatic Habitat Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

 Temperature and Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

 Dissolved Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

 Food Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

 Fish Populations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

 Population Densities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

 Streambed Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

 Literature Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 
THE AUTHORS 

J. S. KRAMMES was in charge of the Station's research on flood and 

sediment reduction in California's north coast ranges, with headquarters 

at Arcata, from 1968 to 1972. He is now assistant to the chief, watershed and aquatic habitat research branch, Forest Service, Washington, 

D. C. A forestry graduate (B.S., 1958; M.S.F., 1963) of the University 

of Montana, he also earned a doctorate in forest hydrology (1968) at 

Oregon State University. He joined the Forest Service in 1958. DAVID 

M. BURNS is a staff forester in the State Forester's office, California 

Division of Forestry, Sacramento. He is a 1959 forestry graduate of the 

University of California, Berkeley. He began his career in the Division 

of Forestry in 1959. The next year, he transferred to the Jackson State 

Forest, headquartered at Fort Bragg. He served as assistant manager of 

the Forest from 1962 until 1968, when he assumed his present 

position. 
SUMMARY 

Krammes, J. S., and David M. Bums. 

1973. Road construction on Caspar Creek watersheds . . . 10-year 

report on impact. Pacific Southwest Forest and Range Exp. 

Stn., Berkeley, Calif. 10 p., illus. (USDA Forest Serv. Res. 

Paper PSW-93) 

Oxford: 383:116.38:(794). 

Retrieval Terms: bridge building; road construction; logging operations; 

environmental impact; streamflow; sedimentation; fish habitat; Caspar 

Creek; California. 

In 1960, Federal and State agencies jointly started 

a long-term study of the effects of logging and road 

building on streamflow, sedimentation, aquatic habitat, and fish populations on two watersheds of Caspar 

Creek, in northern California. The experimental 

watersheds are the North and South Forks of the 

Creek. The data being collected consist of continuous 

streamflow measurements, suspended sediment measured at weirs, changes in sediment deposition in 

debris basins behind the weirs, and rainfall. Effects of 

roads built in summer 1967 were monitored between 

1967 and 1971. 

This paper summarizes data from 10 years of 

streamflow calibration and 4 years of recording 

effects of road construction and use. 

Generally, the immediate impact of right-of-way 

clearing, road building, and bridge construction was 

best reflected in the suspended sediment yield. Turbidity levels were high during the road building 

period, but did not extend far downstream nor persist 

for extended periods during summer. Suspended sediment yields the first winter were more than four 

times the preconstruction levels; subsequent winter 

levels, while still above preconstruction, were not excessive. 

There was a small increase in sediment deposited 

in the basin behind the weir during the first 3 winters 

after road construction, and a major increase the 

fourth winter. An old splash dam located more than 2 

miles upstream from the weir failed during the first 

winter and added over 900 cubic yards of sediment to 

the channel. This surge may have been responsible for 

the fourth winter increase. 

Water temperatures were raised slightly, increasing 

the production of bacteria, algae, and the insects 

upon which fish feed. Dissolved oxygen concentrations were not adversely affected by construction 

activities or by removal of stream-side vegetative 

cover. Road construction did not significantly effect 

the volume of living space for fish populations. 

Young-of-the-year fish populations decreased immediately after road construction. Some of the 

change in population census was the result of migration and of population adjustment to stream 

carrying capacity. The combined populations of steelhead and salmon smolts decreased 20 percent, but 

this decline is estimated to be within the range of 

natural fluctuation reported for other California 

streams. 

Streambed particle size composition changed 

during the period of observation following road construction, but with no deleterious effect on fish habitat. 

The long-term effects of road building and logging 

remain to be established. 

1 
Logging and road building affect streamflow, 

sedimentation, and aquatic habitat in forested 

watersheds. But how decisive an impact do they 

have? And for how long must effects be studied to be 

considered significant? Forest managers would find 

the answers to these and other questions useful in 

determining appropriate methods for timber harvesting and for designing logging roads. 

To come up with some answers, a number of Federal and State agencies in California began a joint 

study in 1960 on two Caspar Creek watersheds of the 

Jackson State Forest, near Fort Bragg, California. The 

agencies participating are the Pacific Southwest Forest and Range Experiment Station, California Division of Forestry, and California State University, 

Humboldt. Earlier participants included the California Departments of Fish and Game and of Water 

Resources. 

The study is designed to develop quantitative data 

on the impact of selection cutting and attendant road 

systems on streamflow, sediment, and fish habitat. In 

applying this cutting technique, about two thirds of 

the timber volume is to be removed. Timber harvesting and road location, design, and construction 

are all to standards consistent with the intensive management objectives of Forestry. Attention to watershed protection values is kept to within practical

limits. The study is not intended to compare differences in types of logging practices or road building 

methods. 

The two experimental watersheds are the North 

and South Forks of Caspar Creek. They are in the 

second-growth, redwood-Douglas-fir forest type (fig. 

1). The Creek flows into the Pacific Ocean about 6 

miles south of Fort Bragg. The South Fork study area 

consists of about 1,047 acres; the North Fork study 

area, about 1,255 acres. Both watersheds were clearcut and burned in the late 1800's. In 1961, both 

supported adequately stocked stands of secondgrowth Douglas-fir, redwood, hemlock, and grand fir 

that ranged from 65 to 85 years old. The timber 

stand in the South Fork averaged 85 years old; the 

stand in the North Fork, 65 years old. Because of the 

age difference, the North Fork was selected as the 

control; and the South Fork as the watershed to be 

selectively harvested. 

This paper reports on streamflow calibrations in the 

two Caspar Creek watersheds during the first 10 

years, and on the effects of road construction during 

a 4-year period on sediment yield, aquatic habitat, 

and fish populations. The findings reported may provide useful information for the prudent management 

of other watersheds, in the north coastal area of California, that have generally similar soils and geology.

SOILS AND GEOLOGY 

The geology of the experimental watersheds 

appears representative of western Mendocino County. 

Sedimentary rocks of Cretaceous age underlie most of 

both watersheds. Soils mapped on these rocks are of 

the Hugo and Mendocino soil series. Rocks underlying the Hugo soils are hard sandstone and shale, 

moderately weathered, coarse-grained, and deeply 

shattered. This kind of fractured substratum receives 

drainage water rapidly, but has only a moderately 

high water-holding capacity. 

In contrast, the sandstone associated with the 

Mendocino soil is highly weathered-often streaked 

with lenses of red and white clay. These rocks appear 

slightly less permeable and were estimated to retain 

slightly more water than those under the Hugo soils.1

Less than 10 percent of the South Fork watershed 

is underlain with weakly consolidated Pleistocene 

marine terrace deposits of sand and gravel. The deposits are the parent material for the Caspar and 

Noyo soils. This substratum is generally firm, moderately permeable, and medium to high in moisture 

retention-a factor that was considered when the beginning of the logging season was set. 

Gladish1

 concluded that the two major soils in the 

experimental watersheds differed only slightly in surface erodibility. Furthermore, sediment sources would 

most likely be associated with logging activities 

adjacent to water courses, and from mass movements, 

particularly where roads cut through dormant 

landslides. 

1

Gladish, E. N. Soils and vegetation of the Caspar Creek 

watersheds. 1963. (Unpublished report on file at California 

Division of Forestry, Sacramento, Calif.) 

3 
Figure 1-The two experimental watersheds in the Caspar Creek study are the 

North and South Forks on the Jackson 

State Forest, in northern California. 

TREATMENTS AND MEASUREMENTS 

Both watersheds were monitored in an undisturbed condition between 1962 and 1966. A main 

haul logging road and spurs were built in the summer 

of 1967 in the South Fork watershed. Effects of the 

roads were monitored between 1967 and 1971. Timber harvesting started in March 1971 in the South 

Fork drainage, and the harvesting effects are to be 

evaluated until about 1977. 

A weir was completed in each fork in November 

1962. The continuing data collected at each site consists of continuous streamflow measurements, suspended sediment measured at the weirs (stagetriggered and supplemented by hand sampling), 

measurement of changes in sediment deposition in 

the debris basins behind the weirs, and rainfall. 

Changes in aquatic habitat upstream from the weir 

were measured periodically at 60 stations in the 

North Fork and 77 stations in the South Fork watershed. Stations were located at 100-foot intervals upstream from the weirs in each fork. 

Two stream channel sections totaling 2,000 feet of 

the South Fork streambed were mapped in detail. 

The maps indicate location and extent of pools and 

riffles, stream width, meander, general nature and extent of bottom materials, prominent landmarks, and 

location and extent of beds of aquatic vegetation. In 

addition, sections of the stream, of bottom materials, 

and of the floral canopy were photographed. The 

sections have not been re-mapped, as there appear to 

be little change in them to date. 

The last phase of the study-the harvesting and 

logging operation-began in March 1971. Timber was 

to be selectively harvested in three consecutive annual 

sales. Starting at the weir and moving upstream, each 

sale would be completed in one logging season. 

Annual sales would remove between 10 and 14 million board feet of timber, averaging about 63 percent 

of the timber stand volume (table 1). Timber harvested from the 1967 road right-of-way clearing was 

included to present a total accounting. 

The three main considerations which led to the 

choice of sale areas and scheduling sequence were: 

1. Timber volume involved in each of the three 

sales is consistent with the State Forest timber sale 

policies. Planned volumes can be removed in one logging season by using available equipment. 

2. Ridge-to-ridge sale boundaries provided the 

most orderly plan for the systematic timber harvest. 

3. Starting the first timber sale near the weir, with 

subsequent sales upstream, should permit better 

evaluation of sediment source areas without having a 

Table 1-Estimated timber sale volume in the South Fork 

watershed, Caspar Creek, Jackson State Forest, California 

Sale Year Acres Harvest Leave 

area 

 - - - - MM. bd. ft. - - - -

Area 1 1971 249 10.3 7.1 

Area 2 1972 316 13.6 6.2 

Area 3 1973 435 12.1 7.9 

 Total - 1,000 36.0 21.2 

Right-of-way 1967 47 4.0 -

 

4 
Figure 2-Typical section of a logging 

road built in the South Fork drainage of 

Caspar Creek. The road was completed 

in September 1967. 

cumulative effect as might happen if the sequence of 

logging were reversed (fig. 1). 

Silvicultural Systems 

The major second-growth stand is now about 95 

years old and consists of redwood (Sequoia sempervirens), Douglas-fir (Pseudotsuga menziesii), grand fir 

(Abies grandis), hemlock (Tsuga heterophylla), and 

bishop pine (Pinus muricata). There are also some 

scattered old-growth trees. 

The selection cutting, as being applied, will remove 

single trees and small groups of trees with the objectives of reserving healthy, fast growing stands of the 

more desirable species, and of providing openings to 

encourage regeneration of the same species. Most of 

the scattered old-growth timber is to be removed. 

About 50 percent of the young-growth redwood and 

Douglas-fir, and about 60 percent of the grand fir, 

trees are to be removed. Hemlock and bishop pine are 

to be marked heavily to favor the other species. 

Near the county roads and the boundary of 

Russian Gulch State Park, marking is lighter, with 

special consideration for esthetic values. Some oldgrowth trees are left. The lighter marking merges in to 

standard marking at 50 to 200 feet, depending on the 

local situation. The light marking should also provide 

a windbreak along the southern perimeter where 

there are sandy soils and trees are susceptible to windthrow. 

Road Construction 

Right-of-way clearing for constructing the logging 

road and main spur roads in the South Fork drainage 

began at the upper end of the watershed in May 1967. 

Generally, clearing and road work progressed downstream toward the weir. 

All road and bridge construction and all stream 

cleaning activities were completed by September 12, 

1967 (fig. 2). About 4.2 miles of road were built, of 

which about 3.7 miles were in the aquatic habitat 

study area. Coarse debris, resulting largely from 

STREAMFLOW AND SEDIMENTATION 

Erosion and Landslides 

Winter rains in 1967-68 resulted in some mass 

movement within road prisms, particularly in the 

right-of-way clearing, that was in the stream and 

along its banks was mostly removed after road construction. 

Some of the road-building and bridge construction 

directly affected the perennial stream, its bed, and its 

banks. Small trees, many branches and leaves, and 

considerable quantities of rock and soil slid into, or 

were deposited at, several locations in the stream. 

Almost the full length of the aquatic habitat study 

area was directly affected in one way or another by 

the road-building activities. About 360 feet of streambed were disturbed by tractor operation directly in 

the stream. These areas were primarily around bridge 

crossing locations, landing sites, and in a stretch of 

stream cleared of debris from right-of-way clearing. 

All fill slopes, landings and major areas of soil exposed by the road-building activities were fertilized 

and seeded with annual ryegrass (Lolium multiflorum) in September 1967. The grass was well established before the first rains in November (Jackman 

and Stoneman 1973).

steeper cut slopes and from fill areas next to bridge 

sites. An estimated 500 cubic yards of soil and rock 

material from cut banks was deposited on the road in 

19 separate slides along 2,000 feet of road. Sixteen 

5 
slides along the fill slopes contributed an estimated 

150 cubic yards directly to stream. No estimate is 

available for volume of material eroded from areas 

next to bridge sites or the amount of material that may 

have spilled into the stream during road maintenance. 

A splash dam had been constructed on the South 

Fork during the first timber harvest in the 1880's for 

transporting logs downstream. This dam, about 

10,800 feet upstream from the South Fork weir, 

failed in December 1967. The road crossed the South 

Fork at a point 300 feet above the old splash dam, on 

the upper end of the estimated 5,600 cubic yards of 

sediment that had been trapped behind the dam. Considerable debris was removed from the channel between the dam and the road crossing. These construction activities may have hastened the dam 

failure. In any case, an estimated 925 cubic yards of 

sediment entered the stream as it cut a new channel 

through the trapped sediment, to be added to material coming directly from road-building activities. 

Most sediment from both sources entered the channel 

during, the winter of 1967-68, and it is not possible to 

say how much of the subsequently measured downstream sedimentation originated from each. 

Peak flow periods during the first winter were not 

of sufficient length or magnitude to transport bed 

material for long distances; hence an unusual amount 

of sediment did not accumulate in the sedimentation 

basin during the 1967-68 measurement. 

By June 1968, the streambed generally did not 

appear much different from the way it looked before 

the roads were built. This lack of visible streambed 

change was due to the distribution and the leveling of 

sediment all along the stream. 

Stream Turbidity 

Road building and associated activities caused 

some turbidity, as was expected. 

Trees felled into the stream, and its tributaries 

tended to increase stream turbidity only slightly 

(p.p.m. concentrations established from turbidometer 

instrument calibration curve). For example, a summer 

falling operation 4,700 feet upstream from the weir 

and on a tributary 4,450 feet above the weir yielded a 

concentration of 11 p.p.m. About 1,000 feet downstream the concentration dropped to 2 p.p.m. These 

concentrations were from samples taken during the 

time of clearing. 

Construction of a bridge 6,700 feet upstream from 

the weir resulted in high turbidity for about 1,000 

feet downstream from the construction site, but it 

apparently had little effect on the concentration beyond a mile downstream. Maximum observed turbidity during the summer low flow period was about 

4,000 p.p.m., caused by a tractor preparing bridge 

footings. The next day, the observed maximum at the 

bridge site was 18 p.p.m.; 700 feet downstream from 

the bridge site, the concentration had returned to the 

observed preconstruction level of around 1 p.p.m. 

The presence of the new road, plus the failure of 

the splash dam, must be held responsible for peak 

increases in turbidity in the South Fork during the 

winter of 1967-68. During a period of moderate rainfall in mid-January 1968 turbidities were as high as 

3,000 p.p.m. in the South Fork study area, at least as 

far upstream as 4,600 feet from the weir. Because 

samples were taken only during visits to the study 

area, they may not represent maximum concentrations. 

Turbidity values greater than the preconstruction 

level were not measured during summer low flow 

periods subsequent to the 1967 road building season.

Suspended Sediment 

Suspended sediment is the parameter most often 

used as an index to estimate erosion from a watershed. Since sediment concentrations under undisturbed conditions vary widely, isolated samples do 

not directly represent watershed conditions. Longterm relationships between suspended load and 

stream discharge must be developed before suspended 

sediment concentrations can be used to evaluate 

treatment effects. 

Anderson (1971) uses weighted sediment concentrations to assess land use changes. His method, related measured suspended sediment concentrations to 

measured streamflow at time of sediment sampling. 

Comparisons are made by applying the sediment 

streamflow relations to normalized streamflow expectancy. Annual suspended sediment yields for normalized expectancy of streamflow and existing watershed conditions were estimated for both Caspar Creek 

drainages (table 2J, very few high flows were sampled 

during the 1962-63 hydrologic year, so that estimates 

are probably not determinable. 

Suspended sediment concentrations during an 

early December, 1967, storm reached 4,036 p.p.m. at 

the South Fork weir sampling location. This runoff 

event transported a sizable portion of the readily 

available fine sediment. A storm in mid-January 1968 

with about the same peak streamflow yielded sediment concentrations of 1,292 p.p.m. The last sizable 

storm during that hydrologic year had a peak flow 

twice that of the earlier storms but produced maximum concentrations of 2,609 p.p.m.

6 
Table 2-Estimated suspended sediment discharge for normalized expectancy of streamflow North and South Forks, 

Caspar Creek, Jackson State Forest, California)1

Hydrologic Year 

(Oct. 1-Sept. 30) 

Caspar Creek 

South Fork 

Caspar Creek 

North Fork 

 - - - - Tons/sq.mile - - - - 

Calibration period: 

1962-1963 2 61 2 130 

1963-1964 160 135 

1964-1965 133 188 

1965-1966 196 193 

1966-1967 221 125 

Road calibration period: 

 

1967-1968 742 151 

1968-1969 215 120 

1969-1970 166 99 

1970-1971 233 109 

1

Based on method outlined by Anderson (1971). These are 

not estimates of actual discharges for the year, but are normalized to a standard streamflow expectancy. 

2

Few high flows sampled, so estimates probably not 

determinable. 

Table 3-Measured deposition in the Caspar Creek Basin,

Jackson State Forest, California 

Hydrologic year 

(Oct. 1-Sept. 30) 

Caspar Creek 

South Fork 

Caspar Creek 

North Fork 

 - - - - Cu. yd./sq. mile - - - -

Calibration period: 

1962-1963 87 64 

1963-1964 45 69 

1964-1965 224 686 

1965-1966 193 793 

1966-1967 109 60 

Road calibration period: 

1967-1968 134 53 

1968-1969 231 391 

1969-1970 147 227 

1970-1971 655 334 

 

The great suspended sediment increase during the 

first year after construction is notable (table 2). Two 

of the remaining 3 years during the road calibration 

period had suspended sediment loads somewhat in 

excess of the mean value estimated for the calibration 

period. Since the estimation procedure normalizes 

suspended sediment discharges for average flow conditions among watersheds, we would conclude that 

the road-building activity and splash dam failure did 

increase suspended sediment discharges markedly 

during the first year after construction, and may have 

caused a small increase in the 3 subsequent years. 

Debris Basin Deposit 

The large increase in sediment deposition in the 

North and South Fork basins in 1964-65, prior to road 

construction, is associated with high flows of the 

December 1964 flood (table 3). 

There was a small increase in weir-basin deposition 

in the South Fork watershed during the first three 

winters after the road building activities ceased, and a 

major increase in the fourth winter, relative to deposition in the North Fork basin. Material side-cast into 

the stream channel during construction, during road 

maintenance, from several small landslides, and from 

splash dam failure moved only during high runoff 

periods, but may have moved only relatively short 

distances during each period. 

It is interesting to note that the South Fork basin 

deposition peaked in the fourth season, whereas the 

suspended sediment peaked in the first. A possiblethough speculative-explanation is that it took the 

additional 3 years for a major part of the sediment 

from the splash dam failure to be transported 10,800 

feet down the channel to the weir basin. 

There is little doubt however, that the sediment 

potential of the South Fork was increased because of 

slope failures in road fills and of erosion around 

bridge sites.

AQUATIC HABITAT CHANGES 

Temperature and Radiation 

Most of the physical, chemical and biological properties of an aquatic system are affected by temperature. Opening of the canopy for road construction 

increased summer water temperatures in the South 

Fork. Most observed summer maximums in both 

forks before road building were below 60°F., in the 

South Fork. The maximum temperature observed in 

the South Fork was 78°F. Water temperatures in the 

undisturbed North Fork remained unchanged. 

Constant exposure to water temperatures higher 

than 78°F. can injure anadromous fish populations. 

Inland streams where late summer and fall seasons are 

usually hot and dry often have maximum temperatures 

in excess of 78° F. Short coastal streams, such as 

Caspar Creek, actually benefit through a slight increase in insolation by stimulating a favorable production in the food chain. Optimum temperatures for 

7 
basic habitat requirements are in the range of observed temperatures in the South Fork drainage. 

Daytime surface water temperatures in the South 

Fork tended to increase between points 11,100 feet 

and 4,700 feet above the weir-the part opened to 

insolation as a result of road building. Warming was 

partially offset by inflow of cold water from springs 

and tributaries. Highest summer water temperatures 

in the South Fork tend to occur between 6,500 and 

3,500 feet upstream from the weir. This trend is consistent with the greatest increase in radiation exchange occurring in the same stream reach as a result 

of exposure by road building. About 1.4 miles of the 

total 4.2 road miles impinge directly on the stream 

channel. Solar radiation data collected over several 

years provide a basic index on the effects of canopy 

removal. A general cooling occurs beginning about 

3,500 feet and continues downstream to the lower 

end of the study area because much of the original 

shade still remains in this lower reach of the stream. 

Other factors which might be altered by increased 

insolation, in addition to stream temperatures, are 

aquatic plant growth and oxygen production and use.

Dissolved Oxygen 

Generally, dissolved oxygen concentrations should 

not be below 6 p.p.m. for growth and well-being of 

anadromous fish and their associated biota. Concentrations should never drop below 4 p.p.m. at any time 

or place; they may range between 5 and 6 p.p.m. for 

short periods provided the water quality is favorable in 

other respects (Federal Water Pollution Control 

Administration 1968). 

During the road construction period of 1967, dissolved oxygen concentrations as low as 5 p.p.m. were 

measured in the South Fork near construction activities and in some isolated pools holding decaying slash. 

The blocking of the streambed, at a location 1,100

FISH POPULATIONS 

One of the most important variables in determining production of anadromous fish species in tributary streams is the amount of available living space. 

Young steelhead trout (Salmo gairdnerii gairdnerii) 

and salmon (Oncorhynchus kirutch) are territorial fish 

(Chapman 1966). Emerging fish establish their 

territories during late spring while water levels are still 

quite high. As the flow diminishes in the summer, fish

with territories at the stream edges are forced to become nomads and to seek new territories. Mortality is 

higher among the displaced fish than among those 

with stable home territories. 

On small streams, the volume of streamflow directly affects living space. Our streamflow records 

show quite a range in summer season runoff. In the 

South Fork, for example, measured streamflow for 

June 1967 was more than double the June 1968 run2

 Hess, L. J. The effects of logging road construction on 

insect drop into a small coastal stream. 1968. (Unpublished 

master's thesis on file at California State College-Humboldt, 

Arcata, Calif.)

G. P. 0.794-469/ 4607 8 

feet upstream from the weir, produced a small reservoir in which oxygen concentrations in flowing water 

areas were from about 7 to 9 p.p.m. The following 

year (1968), the lowest recorded concentration in the 

flowing stream was 7 p.p.m. on June 25-a level not 

far below that of air-saturation under the prevailing 

conditions. Dissolved oxygen concentrations were not 

materially affected by the construction activities or 

by removal of some stream-side vegetative cover. 

Food Production 

On the South Fork of Caspar Creek, the numbers 

of insects falling into the stream were greatly increased after the logging road was built.2

 A twofold 

increase in number and weight of insects occurred 

over the entire stream. In "disturbed" areas, where 

the road paralleled the stream, drop insects increased 

three and one-half times by number and one and 

one-half times by weight over the "control" area. In 

the "highly disturbed" areas, where the road crossed 

the stream, insect numbers increased by five and onehalf times, and a threefold increase by weight over 

the "control" areas was noted. 

A more than proportionate amount of the increase 

occurred in those adult insects having aquatic immature states. One such family, Chironomidae, had a 

greater occurrence after road construction than the 

other 11 families combined had before construction. 

This family showed the most significant increase in 

numbers of all the families studied and provided an 

increased food supply. 

Although the road building activity destroyed 

some of the aquatic invertebrates, other orders of insects offset the losses. Rapid recolonization took 

place in the South Fork. And within 2 years benthos 

increased 370 percent over its biomass prior to road 

construction. During the same period, the North Fork 

benthos increased only 64 percent (Burns 1972). 
off volume and more than three times the 1964 runoff. Higher runoff in late spring contributes to and 

influences population densities in the summer 

months. While studying the carrying capacity of seven 

northern California streams Burns (1971) found 

streamflow volume to be significantly related to 

salmonid biomass. 

In the South Fork watershed, road construction 

did not significantly effect the volume of living space 

for the fish population. 

Yields of juvenile steelhead trout and salmon emigrants were counted in the South Fork before and 

after construction of the logging road. Graves and 

Burns3

 compared the numbers, length, and age-class 

structures. They found more steelhead smolts (age 

class: 1+ years and having characteristic silvery

3

Graves, David S., and James W. Burns. Comparison of the 

yields of downstream migrant salmonids before and after 

logging road construction on the South Fork Caspar Creek, 

Mendocino County. 1970. (Unpublished, Inland Fish. 

Admin. Rep. 70-3, on file at California Dep. Fish and Game, 

Sacramento, Calif.) 

Table 4-Downstream counts of migrants, South Fork, Caspar 

Creek, Jackson State Forest, California, by population 

appearance that develops before emigration) and 

fewer salmon smolt migrants in 1968 than in 1964 

(table 4). The combined migrant populations of steelhead and salmon smolts decreased 20 percent, but 

this combined decrease was estimated to be within 

the range of natural fluctuation reported from other 

northern California streams (Graves and Burns 1970). 

Steelhead and salmon fry (age class: 0- to 3-month 

newly hatched fish) downstream migrants were more 

numerous in 1968 than in 1964. No steelhead fry 

were trapped in 1964; 72 percent of the migrants in 

1968 were fry. Age composition of the salmon also 

shifted markedly from 1964; fry comprised 5 percent 

of the total in 1964, and 81 percent in 1968.

Population Densities 

Population densities (table 5) in the South Fork 

decreased immediately after road construction (Burns 

1972). Population estimates for the North Fork fluctuated (table 6). Recovery in the South Fork began 

the following year and by the second spring the 

salmonid biomass returned to within 9 percent of the 

Table 5-Population densities and numbers of salmonids in South Fork 

Caspar Creek, Jackson State Forest, California 

Population and Steelhead Coho 

year (March 13- trout salmon Total 

July 1) 

Smolts: 

1964 79 581 660 

1968 187 341 528 

Fry: 

1964 0 32 32 

1968 488 1,429 1,917 

Total: 

1964 79 613 692 

1968 675 1,770 2,445 

Source: Graves and Burns 1970. 

 Steelhead Trout Coho 

 Young of year Yearling or older Salmon 

Survey 

date 

 No. per No. No. per No. No. per No. 

 sq. mile sq. mile sq. mile 

June 1967 1.69 10,183 0.11 673 1.00 6,001 

Oct. 1967 .29 1,436 .02 106 .21 1,038 

June 1968 1.32 6,580 .04 176 .50 2,510 

Oct. 1968 .58 2,365 .01 51 .32 1,283 

June 1969 1.45 9,512 .06 407 .77 5,036 

Oct. 1969 .81 3,224 .04 141 .48 1,885 

Source: Burns 1972. 

 Steelhead Trout Coho Salmon 

Survey Young of year Yearling or older 

Date No. per No. No. per No. No. per No. 

 sq. mile sq. mile sq. mile 

June 1967 1.37 6,558 0.02 93 0.07 313 

Oct. 1967 .52 2,015 .02 69 .03 122 

June 1968 1.61 5,801 .02 82 .10 359 

Oct. 1968 .57 1,172 .03 77 .08 194 

June 1969 .81 4,005 .04 211 .55 2,724 

Oct. 1969 .47 1,151 .03 71 .45 1,105 

Source: Burns 1972. 

Table 6-Population densities and number of salmonids in North Fork of 

Caspar Creek, Jackson State Forest, California 

9 
Table 7-Composition of streambed materials, North and South Forks, Caspar 

Creek, Jackson State Forest, California

 South Fork North Fork 

Survey < 0.8 mm. < 3.3 mm. < 26.7 mm. < 0.8 mm. < 3.3 mm. < 27.6 mm. 

Date 

 - - Mean pct. of sample vol. - - 

June 1967 20.6 36.4 73.3 18.4 32.0 72.0 

Oct. 1967 34.2 47.8 77.8 17.5 33.5 79.5 

June 1968 17.9 37.2 84.4 18.2 34.6 78.0 

Oct. 1968 19.0 37.1 74.8 18.0 35.5 75.7 

Aug. 1969 28.5 44.2 75.0 23.2 40.5 80.4 

Source: Burns 1970. 

predisturbed biomass. All age groups of salmonids 

had greater mean lengths after the road construction. 

Comparison of steelhead smolt lengths was difficult 

because of the emigration of more than one age class. 

The two large weir ponds, and a fish ladder upstream from the emigrant traps, obscured the impact 

of stream habitat alteration by providing refuge for 

fish during road construction and right-of-way logging. Some of the population decrease in the South 

Fork in 1967 may have resulted from migration of 

some large steelhead trout from the study area to the 

pools formed behind the streamflow gaging and fish 

trapping facility. The ponds made up about 20 percent of the total salmonid habitat. In all probability, 

then, not all the decrease in 1967 population densities can be considered mortality (table 5). 

Streambed Composition 

Streambed conditions can affect fish habitat. Compacted streambeds prevent digging of redds, reduce 

supply of oxygen to the eggs, and prevent emergence 

of fry. Large proportions of fine sediment may fill 

the voids to reduce fry emergence and intergravel 

oxygen flow. 

As a measure of salmon and trout production, 

streambed conditions were evaluated in both watersheds. During three consecutive seasons, the California Department of Fish and Game collected 

quantitative data on the changes of sediment sizes 

within the streambed (Burns 1970) (table 7). In the 

South Fork watershed, the volume of fine sand and 

smaller size particles increased immediately after road 

construction, but were about the same the summer 

after the first runoff season. Survey data collected 

about 2 years after road construction show an increase in the smaller size fractions. A similar trend 

was found in the North Fork watershed. 

Streambed gravel conditions are most critical 

during the winter runoff period when eggs are deposited and in the spring when fry emerge. Within that 

same period, the streambed was undergoing constant change owing to peak runoff events. Even 

though there was a change in the composition of the 

streambed particle size, it did not materially affect 

fish populations. 

LITERATURE CITED 

Anderson, Henry W. 

1971. Relative contributions of sediment from source 

areas and transport processes. Proc. Symp. Forest 

Land Uses and Stream Environment, Corvallis, Ore. 

1970: 55-63. 

Burns, James W. 

1970. Spawning bed sedimentation studies in northern 

California streams. Calif. Fish and Game 56(4): 

253-270. 

Burns, James W. 

1971. The carrying capacity for juvenile salmonids in 

some northern California streams. Calif. Fish and 

Game 57(1): 44-57. 

Burns, James W. 

1972. Some effects of logging and associated road construction on northern California streams.

Trans. Amer. Fisheries Soc. 101(1): 1-17. 

Chapman, D. W. 

1966. Food and space as regulators of salmonid 

populations in streams. Amer. Naturalist 

100(913): 345-357. 

Federal Water Pollution Control Administration. 

1968. Water quality criteria. Report of the National 

Technical Committee to the Secretary of 

Interior. 234 p. Washington, D.C.: U.S. 

Government Printing Office. 

Jackman, Raymond E., and Norman N. Stoneman. 

1973. Roadside grassing-a post-logging practice for 

Redwood forests. J. For. 71(2): 90-92. 

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