NATURAL AND ARTIFICIAL LAKES 



serious objection to many garden lakes. This is sup- 

 posed to be simply a sign of stagnation, and a plague 

 difficult to overcome. In reality, it may be as easily 

 managed as the mosquito troubles. Thanks are due 

 to the Government Department of Agriculture for 

 the remedy that is certain to obliterate this yellowish- 

 green scum, and to keep it from forming in the 

 future. For many years this nuisance, which is 

 sometimes called "purging," has made thousands 

 of fresh-water lakes and mill ponds throughout the 

 United States unsightly and unhealthy. The suc- 

 sessful experiments of the Department of Agricul- 

 ture in treating these bodies of water are of equal 

 advantage in treating the garden lakes. 



According to the expert authority of the Depart- 

 ment, this green scum is the formation of algae in the 

 water. It becomes an important matter to remedy 

 the formation, and to keep pure and fit for use the 

 public water supplies, that in the past were practi- 

 cally useless for months at a time because of that 

 troublesome algae. It has been found that it can be 

 thoroughly controlled by the use of copper sulphate, 

 which is the "blue vitriol" of our well-known 

 Bordeaux mixture. 



The trouble with the average home gardener, in 

 experimenting with this cure, is his tendency to use 

 too much of it. It is better to follow closely the given 



57 



