6 8 10 12 |i| 16 

 RIVER MILES FROM LAKE 



20 22 



EFFECT OF LAKE KEGONSA ALGAE ON YAHARA RIVER 

 OXYGEN RESOURCES 



Figure 9 



waste stabilization and is readily lost to the at- 

 mosphere . This type of loss applies in principle to 

 rivers also but usually occurs there at a much lower 

 degree of intensity. For waste stabilization it 

 would be far better that oxygen be available con- 

 tinuously at a lower but constant level than the 

 "feast and famine" situation that occurs naturally. 



Death of fish has been reported in natural 

 waters where high concentrations of dissolved oxy- 

 gen were produced by a bloom of Chlamydomonas 

 (Woodbury, 1941). At oxygen concentrations of 

 30-32 ppm. , characteristic lesions of the fish con- 

 sisted primarily of gas emboli in the gill capillaries 

 and gas bubbles in the subcutaneous tissues. Al- 

 though not tested, the gas was believed to be oxy- 

 gen. Occurrences such as this are not common. 



The Lower Fox River mentioned above is an 

 example of a stream that receives its principal flow 

 from a lake (L. Winnebago). During late summer 

 and early fall, tons of algae produced in the lake 

 enter the river and move downstream. Prominent in 

 the phytoplankton are large quantities of Anabaena , 

 Aphanizomenon , and Microcystis , which are more 

 characteristic of standing than flowing water. 

 These algae are reduced in numbers progressively 

 downstream, apparently by dying off. Field and 

 laboratory study showed that seasonal decomposi- 

 tion of such algae is a serious factor in decreasing 

 the assimilation capacity of the river, which re- 

 ceives residual wastes from several cities and from 

 pulp and paper mills. 



Another more explosive example of excessive 



use of oxygen resources by algae occurred in the 

 Yahara River in Wisconsin (Mackenthun, Herman 

 and Bartsch, 1945, Published in 1948) where, in 

 October of 1946, tremendous quantities of blue- 

 green algae, almost entirely Aphanizomenon flos 

 aquae , entered from Lake Kegonsa . Decomposing 

 as they passed, wave-like, downstream, they de- 

 pleted the oxygen supply, thus causing the death 

 of tons of fish. Although algal toxicants were 

 present, oxygen conditions were sufficiently severe 

 to account for the fish mortality. The pattern of 

 progressive oxygen depression and recovery that 

 accompanied the mass movement of algae is shown 

 in Figure 9. Fish mortality occurred 3-1/2 miles 

 from the lake three days after algae entered the 

 river, at 6 miles after five days, and at 18 miles 

 after eight days . 



Effects of Algae on the B.O.D. Determination 



The oxidation processes of algae that con- 

 tinue to occur in the absence of light in nature per- 

 sist also in the laboratory in conduct of the widely 

 used standard B.O.D. test (Anon., 1955). Ordi- 

 narily, the test result is used with other data to 

 estimate the oxygen conditions that will occur at 

 selected stream points in response to waste loading 

 at others . Sufficient numbers of algae in stream 

 samples collected as a step in such stream analysis 

 affect applicability of the B.O.D. result because: 

 (a) incubation in darkness for the standard five-day 



65 



