silted waters. Smith (19) states that most spawning occurs in the clear 
water of the tributaries. Other observers report that spawning in 
glacial streams is generally confined to areas where the water velocity 
is great enough to prevent silting of the streambed. 
Most salmon streams carry natural silt during flood stages. This 
material reaches stream channels by (1) surface runoff, (2) undercutting 
of channel banks, (3) slow gravitational creep of mantle material, and 
(4) avalanches and land slides. The formation of mud flats and the 
presence of silt at the mouths of most creeks and rivers in Southeast 
Alaska attest to the magnitude of the siltation process under natural 
conditions. 
Most logging activities on watershed slopes tend to disturb the soil 
and increase erosion. Construction of logging roads, however, has 
generally been considered to be the principal source of stream turbidity 
and sedimentation. It is estimated that the construction of access 
roads accounts for 75 percent, or more, of the stream turbidity and 
sedimentation associated with logged watersheds in the States,2L 
Sedimentation resulting from road construction may be minimized by 
(1) location of roads away from stream channels, on benches and ridges, 
with as little side-hill construction as possible, and (2) endhauling 
to reduce overcasting on side hills where fill material may erode 
directly into stream channels. Road construction on the Maybeso Creek 
drainage has not resulted in excessive siltation because roads have 
been located well away from the streams and have generally been con- 
structed by borrowing and endhauling sub-grade material; side-hill 
road construction and sidecasting have been held to a minimum. 
Material suitable for road-subgrade and surfacing is limited in this 
region. Two sources of road-building material are available, rock out- 
crops and stream deposits. Rock outcrops, which consist mostly of 
shales and greenstone in the general area under study, must be quarried. 
Stream deposits are glacial tills which have been reworked and sorted 
by stream action. These deposits contain a rather high content of silt 
and clay and it is generally necessary to first remove these fines by 
washing before the material is used for road-building purposes. 
A large portion of the road-building material used in the Maybeso Creek 
sale area has been obtained from a small stream, Half-Mile Creek, 
which empties into the tidal zone below the mouth of Maybeso Creek 
(fig. 4). Approximately 100,000 cubic yards of sub-grade and surfacing 
material have been removed. A detailed study was made in 1955 to 
21/ Bullard, William. Use of water supply watersheds for road 
construction and logging operations. Talk given to joint meeting of 
Pollution Control Council and Columbia Basin Inter-Agency Sub- 
committee on Pollution Control at Harrison Hot Springs, B. C., 
Sepe. 13, L95h- 
iN hee 
