Biological Survey — Oswego Watershed 117 



were investigated. The manner in which springs occur is regu- 

 lated by geological structure, so that as a result there exist many 

 varieties. Some issue in greater or lesser volume from several 

 spots indicating that the downward seepage of surface water has 

 been interrupted by some impervious stratum, and the flow de- 

 flected in accordance with the dip or inclination of such. These 

 springs have been referred to in the tables as surface springs, An 

 important fact in connection with these is that the water seeping 

 through the upper soils and sub-soils has opportunity for correcting 

 any great deficiency in oxygen, which of course is necessary if 

 the issuing waters are to be suitable directly for fish life. 



Contrasted to these are the deeper seated springs whose issue 

 depends upon the alternations of permeable and impermeable 

 strata, and which may be the outlets of underground streams hav- 

 ing in some cases fairly defined channels. Geological fault fissures 

 or joints afford facilities often-times for the escape of such waters, 

 especially where they bring steeply inclined porous strata against 

 impervious ones. The important fact about these is that the water 

 is rushed to the surface, and its condition depends upon the chemi- 

 cal changes which its constituents have undergone, and the nature 

 of the strata such as limestone with whi^h it has come in contact 

 since it fell as rain at some time and place. Hence as in the case 

 of the Price spring, 1 such waters may be practically devoid of 

 oxygen and highly charged with carbon dioxide, under which con- 

 ditions fish could not exist. 



Lake Studies. 2 — Chemical characteristics of the more important 

 lakes of the watershed were studied. Results are tabulated in Series 

 III. No remarkable seasonal change w r as found, and at those sta- 

 tions where periodic examinations were made, determinations at 

 one period did not differ greatly from those at another. 



It is interesting to note that at the comparatively shallow depth 

 of nineteen meters Otisco lake was found to be only about 3 per 

 cent saturated with dissolved oxygen. 



i See p. 120. 



2 Data supplied by W. L. Tressler, S. S. Britten, and R. Vingee. 



