HALIFAX WATER WORKS. JOHNSTON. 87 



acres in Fish Pond. The geological formation is similar to 

 that of the Long Lake water-shed, but the slopes are somewhat 

 flatter. Mr. Keefer estimated the yield from this gathering 

 ground in the driest year at an average of one and one-quarter 

 million gallDns per day, a^nd that in wet years this amount 

 would be doubled. The storage capacity of the lake is estimated 

 to be 700,000,000 gallons, or sufficient for a population of 

 31,000 for 225 days, allowing 100 gallons per day per capita. 



Cleaning Lakes. 



In raising the Spruce Hill Lakes, the area flooded was 

 thickly covered with trees, brushwood and moss, which appar- 

 ently had never been clea'aed out, and which after a short time 

 died and greatly comtaminated the water. 



The effect was so bad that for a few years previous to 1876 

 the water became imfit for domestic use. In that year the lake 

 was drawn down to a level of 7 feet 9 inches below the waste- 

 weir, and the bed of the lake was cleared of fallen trees, brush- 

 wood and decomposed vegetable matter, and the stumps were 

 grubbed out. The trees a'nd stumps taken out were covered 

 with a green slime. When Long Lake was raised, the shores 

 Avere thoi-oughly cleared, but in common with all the lakes 

 certain forms of vegetation thrive between high and and low- 

 water level, and it has to l)e ])eriodically cleaned out. 



Growths. 



The growth of algse was first noticed in 1878. In that year 

 samples of water, algae and mud from Chain Lakes and water 

 from Long and Spruce Hill Lakes were collected in September 

 when the water was low atid sent to Professor Lawson to 

 analyze. His analysis of water from Long Lake yielded a dry, 

 solid residue, as follows : — 



Inorganic matter 1.71 grains to the gaUon. 



Organic " 2.1.3 



Total 3.84 " 



