Tlie Water Supply of Minneapolis — Committee. 41 



that taken into the piinip-hoiise at present. But even the water 

 now taken and supplied to the city does not reveal to chemical 

 tests a decidedly bad character. 



To pass on to the biological part of the investigaticn,it should 

 be said in the first place that the winter season is an unfavorable 

 one for the purpose. The result of an investigation of the ani- 

 mal life found in the waters about Minneapolis in winter can have, 

 at best, but a negative value. Water taken in February from 

 near the location of the nevv in-take pipe of the city water-works 

 was found to contain very few organic impurities visible by means 

 of the microscope. A few orthopterous larvae, Thysantirae^ occur. 

 Water taken from a hydrant near the corner of Sixth street and 

 Nicollet avenue in June last, however, exhibited considerable 

 quantities of animal and vegetable impurities. Among the latter 

 were algae of the genera ClosteriumStaurastrtim^ Nostoc^ Spiror/f/ra^ 

 etc., together with diatoms and the like. Among the former were 

 several species of entomostraca, as Bosminafierlodaphnia and sev- 

 eral Lynceids, rotifers and infusoria, and an unusually large 

 proportion of parasitic worms. A study of the waters of our larg- 

 er lakes in winter shows that those forms of life which may be 

 regarded as danger signals are absent or few in number, in other 

 words the conditions are not favorable for such animals as inhabit 

 by preference putrid waters. In larger lakes fed by springs are 

 found minute crustaceans, such as Daphnia pulex and species of 

 Diaptomus^ Cyclops fluviatilis and others; while in the smaller 

 lakes the common pond Cyclops species, with the associated Can- 

 thocampus are almost the only entomostraca. To this fact is due 

 the survival of fish in the larger lakes, which perish in others even 

 if sufficiently yentilated. That portion of the Mississippi which 

 lies immediately about the mouth of Bassett's creek is subject 

 during the summer to constant contamination from the numerous 

 marshes, slums and ditches which border that creek and fester and 

 rot in the sun. The figures given below show how enormous 

 a number of animal forms are supported by the filth in the pool 

 known as Oak Lake. In a quart of water dipped from Oak Lake 

 the following were counted: — 



Ceriodaphnia, 1,400. Amphipods, 120. 



Daphnia, 0. Infusoria, 85. 



Simocephalus, 56. Mollusks, 22. 



Cypris, 50. Diptera(larvae)100. 



Cyclops, 28. Hemiptera, 9. 



