RIVERS. 11 



From this point to l^ake C<eur d'Alene, a distance of 48 kilometers (29 

 miles), the river has an almost imperceptible current and a depth in 

 low water of from 5 to 14 meters (16 to 46 feet). The width of the OoBur 

 d'Alene Itiver at the head of navigation is about .'is meters (125 feet), 

 with a summer stage of water of 2.5 meters (8 feet). The total fall in 

 the river from the head of summer navigation to Lake Cueur d'Alene 

 is only about 5 meters (16.4 feet). 



The St. Joseph River is the largest of the Coeur d'Alene streams, and 

 drains the most extensive area. It empties into Lake Cceur d'Alene at 

 the southern extremity, and is navigable for the lake steamers a distance 

 of 42 kilometers (26 miles) from its mouth. The area covered by its 

 basin is trapezoidal in shape. About 24 kilometers (15 miles) from its 

 outlet into Lake C(eur d'Alene it receives its largest tributary, the St. 

 Mary lliver. About 65 kilometers (40 miles) from its outlet it forks 

 into three streams, two of which head in the ridges which form the 

 divide between the North Fork of the Clearwater and the Coeur d'Alene 

 basin. The third heads in the Bitter Root Range a short distance 

 south of Stevens Peak." This latter is the longest of the tributaries, 

 and might be regarded as the continuation of the main stream. If so, 

 the length of the St. Joseph would be about 220 kilometers (or slightly 

 more than l.'J7 miles). 



The elevation of the upper portion of the valleys of the St. Joseph 

 forks is, in the mean, 1,500 meters (4,000 feet), and of the valley at the 

 head of navigation 670 meters (2,108 feet). From the head of naviga- 

 tion to the outlet of the river into Lake Coeur d'Alene there is a fall of 

 about 7 meters (23 feet). The navigable portion of the C<eur d'Alene 

 and St. Joseph rivers is usudly called "the slack water." 



The St. Mary River, the largest tributary received by the St. Joseph, 

 heads in part in the divide which separates the Clearwater from the 

 Occur d'Alene basin and in part in the divides in which the Palouse 

 River heads. The upper portion of its valley has an elevation in the 

 mean of 1,050 meters (about 3,400 feet), and the lower, at its junction 

 with the St. Joseph, a height of about 675 meters (about 2.200 feet). 

 It has a width at its junction of about 8 meters (26 feet), and a depth 

 during the summer stage of water of about 3 meters (10 feet). 



The lower iind navigable portions of these streams all agree in having 

 but a slight fall and adeep channel. This is due to the fact that this 

 portion of their course is cut through a deep diluvial soil, clearly the 

 old bottom of Lake C<Bur d'Alene, which, not so very remotely in a 

 geological sense, was far larger and extended well up into what is now 

 in part the valleys of these rivers. Above the slack water the streams 

 are clear, and do not deposit sufficient sediment to fill up the channels. 

 The valleys rise rapidly, the mountains close in, and the current becomes 

 swift, with shallow water during the summer season. The surface water, 

 however, by no means represents the true amount which drains away 

 by these streams. The subsoil in the valleys is a mass of porous gravel, 



7203— Xo. 1 2 



