of dissolved oxygen. In Lincoln Lakes, In summer, they cannot be expected to live 

 below a depth of 15 feet. Bullheads, however, do not require such a high concentra- 

 tion of oxygen as the other kinds of fish of Lincoln Lakes. Both the black bullhead 

 and the yellow bullhead can tolerate an oxygen concentration as low as one-half part 

 per million. 



TABLE 18.— CHEMICAL ANALYSES OF WATER FROM SPORTSMEN'S LAKE. 



The transparency of Sportsmen's Lake on the day It was first poisoned (tlay 20, 

 1938) was 3 feet, as measured by a Secchl disc. Later, on June 2, after the silt rolled 

 by the fish had settled, the transparency was 9 feet. A heavy crop of plankton algae 

 had reduced the transparency on August 12 to 4 feet 3 Inches. On November 16 It was 

 again 3 feet. 



Lincoln Lakes on August 12 showed a transparency of 3 feet 9 Inches. 



Chemical analyses were made by Mr. J. B. Swartz of the State Water Survey on 

 samples of water collected from Sportsmen's Lake on April 30 and November 16, 1938. 

 These analyses are shown In table 18. 



COARSE AQUATIC PLANTS 



Lincoln Lakes support very few submerged, coarse aquatic plants. At various times 

 In the past, attempts have been made to establish several kinds. Some years ago the 

 curly-leaved potamogeton (Potamogeton crispus) was planted near the bathing beach. It 

 spread over the beach so rapidly that It became objectionable to bathers and was pulled 

 up. At present very little of this plant Is left, and It has not caused trouble on the 

 bathing beach since Its peak of abundance. 



At the time Sportsmen's Lake was poisoned (May 20) It contained only a very sparse, 

 short growth of Potamogeton foliosus In one of the larger necks of water where the 

 transparency was somewhat greater than In the rest of the pond. 



On May 26-28, 1938, members of the Logan County Sportsmen's Club collected a truck- 

 load of aquatic vegetation from some old strip mine ponds near Oakwood, Illinois, and 

 planted It in Sportsmen's Lake, This load consisted of Ceratophyllum. Myriophyllum, 

 Banunoulus, Chara and several species of Potamogeton (including P. foliosus ) . Plantings 

 were made along the shores and In the narrow necks. An Inspection on August 12 showed 

 that P. foliosus had "taken" the pond. It was abundant In all the necks and along the 

 shores, growing In as much as 5 feet of water. A few thrifty plants of Ceratophyllum 

 were present near the levee. 



On November 16, the Potamogeton foliosus had entirely disappeared, but some other 

 forms were growing more or less abundantly. Collections made In shallow water near the 



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