\ 



KARLUK KIVER RED -SALMON INVESTIGATION 5 



and in consequence the shore bench is very narrow and the bottom slopes steeply 

 away from the shores. In general, the narrow beaches are composed of gravel and 

 bowlders of varying size. Along the head of the lake, the head of the Thumb, the 

 foot of the lake, and at a few other scattered places, the beaches slope somewhat 

 more gradually than elsewhere and the gravel is of a size that makes these beaches 

 suitable for spawning. In reality the lake consists of three distinct basins — one 

 including the lower 3 miles, another including the Thumb, and the third and largest 

 basin including the main upper arm. It seems probable that the main arm and the 

 Thumb were formed by two glaciers which met and united just below where the 

 islands now are situated. Apparently a small terminal moraine, which does not 

 now rise to the present surface of the lake, forms the slight elevation that separates 

 the lower basin from the two upper ones. The greatest depths of the lake are found 

 in the lower part of the main arm, immediately above its junction with the Thumb, 

 where a narrow, deep trough, 2 miles long, slightly exceeds a depth of 120 meters. 



From the lower end of the lake, Karluk River flows tortuously in a westerly 

 direction for about 2 miles; then in a northerly direction, along the western side of 

 the valley, for some 8 miles more. At this point it is within some 3 miles of the 

 upper end of Larsen Bay, an arm of Uyak Bay, and here there is a portage trail 

 connecting Larsen Bay with the river. It was at this point that the upper weir was 

 built and maintained during the season of 1926, as mentioned hereafter in the 

 section dealing with the enumeration of the spawning escapement. Thus far the 

 river has followed the northward extension of the valley in which the lake is situated, 

 but it now turns westward and cuts through the mountains of the western side of 

 the valley, and thence flows through generally mountainous country to the coast. 



The descent of the river during the first 10 miles below the lake is approximately 

 50 feet, and most of this drop occurs in the first 4 or 5 miles. Here the river is swift 

 and shallow, but in the next 4 or 5 miles, just above the portage trail to Larsen 

 Bay, the river is deeper, wider, and flows much more slowly. During the late summer 

 and fall this comparatively quiet portion is so filled with a dense growth of aquatic 

 plants, chiefly the water crowfoot, Ranunculus aquaticus, and two species of Pota- 

 mogeton, that it is almost impossible to navigate either with motor or oars. Below 

 the portage the descent of the river is more rapid, falling about 300 feet in the 15 

 or 20 miles between the portage and the mouth of the river. About 4 miles above 

 the mouth, the river widens out into a broad lagoon or estuary, which is shut off from 

 the ocean by a narrow spit only 100 yards or so in width. The mouth of the river 

 is at the western end of this spit. On the ebb tide a strong current flows out through 

 the mouth, but on the flood tide an almost equally strong flow of ocean water takes 

 place into the lagoon. The lower end of the lagoon, therefore, is at times very 

 brackish, but brackish water is seldom if ever noted near the upper end. The spit 

 that separates the lagoon from the ocean is important, since a large part of the 

 commercial fishery for salmon at Karluk is carried on along its outer beach. 



There are no large tributaries to the river below the lake. A few small streams 

 enter, mostly from the eastern side, and these are used as spawning streams by the 

 silver and king salmon. There are, in addition, numerous very small streams, 

 which enter the river all along its course and drain the tundra flats and the smaller 

 valleys of the hills and mountains through which the river flows. 



