map measurer) o->y A sizable portion of this area is occupied by inter- 

 mittent tributaries^ many of which flow only during a short period 

 in the spring. From the standpoint of physical characteristics, 

 the river is divided, rather sharply, into three zones (Figure 28), 

 each representing about one-third of the -watershed. These zones 

 form the basis of subsequent discussions relating to the spaiwiing 

 behavior of the sea lamprey. A description of each zone, beginning 

 at the head-waters of the river and -working do-v/nstreaxa to the 

 estuary follo-svs. 



Zone 3„ — (Stations 3A-31, Figure 28) The river rises in Marl 

 Bed Lake (T33H, RliE, So 23) and from a chain of lakes and marshes 

 in T33 and 3lj.N, Rli2S, -which are scattered over 25 square miles of 

 an irregular, sandy drift area (Leverett, 1912). Both main channel 

 and tributaries, except "i-fhere lalces interrupt the course, flo-vT 

 altnost continuously through ivide, open marshes, bog meado\vs, or 

 cedar si.¥amps. In this, the upper third of the river where the main 

 channel travels approximately 8.5 niiles, -the -ividth of the stream 

 varies from II (Station 31) to 30 feet (Station 3H) and the depth 

 from 12 to 36 inches. The bottom is predominantly muck or siltj 

 ■the velocity of florr is seldom m.ore than sluggish and occasionally 

 in the main channel it was barely discernible (Station 3K). All 

 tributaries examined were essentially of the same -nature (Appendi:>c G, 

 Table 1), Ko channel velocity measurements were made. 



The character of the river and its watershed alters rather 

 abruptly in the neighborhood of an old, cement dam (head: 18 inches) 

 located just upstrea^-i from the crossing of County HighTray 638. 

 This point delimits Zone 3 from Zone 2, next do-tmstream. 



Zone 2. —(Stations 2A-2I, Figure 28) Zone 2, the midportion 

 of -the watershed, extends from the aforementioned cement dam 

 (Station 21 ) dovmstream to the Ocqueoc Falls through boulder-clay 

 plains (Leverett, 1912). Bet-ween these points, the main channel 

 runs about 7.7 miles. At nine survey stations the river ranged 

 from. IS to 50 feet in mdth and from 5 to 12 inches in depth. Pools 

 \rere infrequent and, where present, seldom more than 2l|. inches deep. 

 The gradient is gi'eater in this zone than else-where in the river 

 and T.he mean channel velocity was generally moderate, varying from 

 2„5 to 3,1 feet per second. Bottom types in the lower hail of this 

 zone (stations 2A-2E) are composed predominantly of a miicture of 

 boulders, rubble, and coarse gravel distributed more or less uni- 

 fo:nnly i,n bcth riffles and shallow pools. Limestone outcroppir.gs 

 near Station 2C produce several low falls (12 to 2k inches). Shal-^ 

 lo'w riffle areas 25 to 100 yards long in which the current . is 

 quite rapid are common in this area. Most of the remainder of the 



V Main stream: 13 miles (?); tributary streams: 76 miles (?); 

 estmated drainage area; I6O sq, miles, (from) Brovm, C. J. D., 

 I9I1.I4, Michigan streams — their lengths, distribution and drainage 

 areas. Mich. Dept- Cons., Inst, Fish, Res., Misc. Publ. No. 1, 

 July, 19UU. 



- 85 - 



