28 A. D. Hardy: 



may have been unhealthy, as the fry raised in the Zoological 

 Gardens have not suffered from disease, though a few died, 

 thinks Mr. Le Souef, from overcrowding. In the Studley Park 

 ponds now under notice, brown, rainbow and Lochleven trout 

 are being reared. These are respectively Sahno fario, S. irideus 

 and S. leveiiettsis. 



The ponds comprise six excavations measuring about 14 

 metres long x 5 m. broad; depth of water about 1.5 m. Each 

 receives its own supply, and has a separate outlet of water. 

 The supply is from the Yarra Yarra River, wlience it is 

 pumped up to a circular masonry reservoir in Studley Park. 

 From the reservoir, which is close to the ponds, the water is 

 conveyed by underground pipes to the pond's enclosure, thence 

 by open channels in the ground, and in open wooden flumes. 

 The pump which is used for filling the resei'voir with river 

 water is near to and below the weir at Bight's Falls, and the 

 river, above and below, is polluted mainly by drainage from the 

 populous suburbs on the basaltic flats on the opposite side. 

 Though the sewerage works extension has greatly reduced the 

 evil, there is still much that is injurious entering the river by 

 way of Reilly-street and other drains, Merri Merri Creek, 

 Darebin Creek, etc. 



Conditions inimical to the welfare of young fry, which 

 had hitherto rejoiced in the purity of the metropolitan 

 domestic supply of water from, the Yan Yean and Maroondah 

 systems, were obtained during the prolonged, fierce heat of the 

 Christmas and New Year holidays, when pumping operations 

 partly ceased, and the water in the reservoir fell to a low 

 level. The reservoir, used for irrigating public gardens, and 

 for hydraulic elevators, at times contained a consideiable 

 amount of silt. In addition to the direct rays of the sun, a 

 great amount of heat was reflected from the face of the sur- 

 rounding stonework. The pipes from the reservoir were not 

 deeply buried, and the liai'd ground was fairly warm during 

 the hot weather. Thus the temperature of water in the ponds 

 rapidly rose until a maxianurn of 77 degrees Fahr. was reached 

 during an air temperature of about 100 degrees in the shade. 



The first sign of trouble was the appearance, near the surface, 

 of rainbow fry of sluggish habit, and these became gradually 



