l82 



NORTH SHORE iPRESH-WATER PROBLEM. 



In general, a country with a rolling or varied topography is 

 not supposed to produce many mosquito-breeding places, yet the 

 North Shore of Long Island is an exception. The fact is due to 

 the geology of the region. As is well known, it consists of the 

 terminal moraine of the old ice cap which overran Northern 

 United States and dug out Long Island Sound. In their retreat 

 the glaciers left numerous kettle holes and depressions which 

 have filled with water, which, owing to the impervious clay sub- 

 soil, does not seep away readily. These small ponds have become 

 filled or surrounded by acquatic or semi-acquatic vegetation and 

 make ideal fresh-water and anopheline breeding places. As 

 usual, the works of man have increased the number of danger 

 spots. On the North Shore this has been largely by the erection 

 of dams across the courses of the small streams flowing into the 

 Sound. Active erosion has partly filled and turned into swampy 

 breeders many of these artificial ponds. 



The solution of the problems on the North Shore involves 

 engineering features of various kinds — cleaning and deepening 

 of ponds, changing their water level, filling and ditching of 

 swamps, not to mention oiling and stocking with fish where 

 these remedies are necessary. Often some nice problems in 

 landscape engineering are presented to the mosquito expert in 

 the course of such work. The Commission took over a number 

 of importaint fresh-water drainage projects on the North Shore, 

 some of which have been completed, others will be carried for- 

 ward next year, and new ones started. Some $2,400.00 has 

 been expended by the Commission for fresh- water drainage work 

 on the North Shore in addition to the amounts expended by the 

 various associations. The Commission also expended $3,500.00', 

 which was contributed by a few owners of large estates at Syos- 

 set, in the center of the county, for draining an extensive fresh- 

 water area. 



As an indication of what has already been accompHshed on 

 the North Shore, it may be mentioned that in 191 5 some 350 

 cases of malaria were reported from part of the region under 



