xliv FISHES OF ILLINOIS 



POX RIVER 



Fox River rises in Waukesha county, Wisconsin, a little north- 

 west of Milwaukee. It flows south and southwest, emptying into 

 the Illinois River at Ottawa, 111. Tts drainage basin is about 130 

 miles in length and averages 20 miles in width, covering an area of 

 about 2,697 square miles, of which 1,080 lie in Wisconsin. The 

 length of the river is about ISO miles. 



The low-water discharge is estimated to be 526 cubic feet per sec- 

 ond, or 0. 195 cubic feet per second per square mile. It is claimed 

 that the stream has fallen off one-half in its low-water volume since 

 the clearing and cultivating of the land and the draining of the 

 swamps. 



The drainage basin of the Fox lies entirely within the limits of 

 the Wisconsin glaciation, and is an undulating prairie land with 

 more or less woodland and some swamps. In this region the mo- 

 rainic ridges lie very close together and are often interlaced, thus 

 making cups or kettles within which lakes were formed. Some of 

 these lakes have been drained so thoroughly that they have become 

 small prairies, while in other places they have been unable to cut 

 down their outlets sufficiently. We have, consequently, a series 

 ranging from quiet land-locked ponds with gravel bottoms to 

 marshes differing but little from the ordinary wet prairie or slough, 

 peat bogs, and the dry prairie land. The bed of the swamps is gen- 

 erally more or less peaty, varying in composition from ordinary 

 black swamp muck to true peat. A few of the lakes are from four 

 to seven miles in length and a mile or more in breadth, while the 

 others usually cover only one or two square miles, or even less. 

 These numerous lakelets, ponds, marshes, and bogs furnish, in their 

 aggregate, a considerable storage for flood waters, and the volume of 

 the. stream is consequently comparatively uniform and its changes 

 of level are relatively slow. The water of the upper reaches of Ihe 

 river are usually clear except in times of flood, but the lower part of 

 the stream is often very impure. Though much of the river bed 

 below Elgin is in rock, the tributaries often bring large amounts of 

 sediment, and various manufactories along the river discharge a 

 large amount of refuse into the stream, and it has, of late years, be- 

 come so foul that nearly all fish except carp and other filth-enduring 

 species have been drowned out. 



For a distance of nearly 7 5 miles from its source Fox River drains 

 only a narrow strip among the morainic ridges of the composite belt, 

 its course being determined by a moraine lying on either side. In 

 this portion of its course its fall amounts to only a few inches to the 



