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1!)05, the daiu was very carefully constructed of good clean clay, with 

 a concrete core carried down into the rock far enough to prevent any 

 likelihood of leakage through the substratum. As soon as this pond 

 filled, nevertheless, severe leaks developed under the spillway, through 

 the crevices of the rock, as in the case of the old dam. It is thought that 

 some of the water appearing at this leak actually comes from the upper 

 (fir.st) pond, making the entire journey through the cavernous rock of 

 the valley-side. An attempt was next made to repair this leak by tun- 

 neling into the valley side at the spillway. This excavation developed 

 Ihe fact that there is a mud-filled seam, extending back into the hill be- 

 tween two layers of limestone. This seam was followed back into the hill 

 about 40 feet, and as it showed no sign of closing up, the portion excavated 

 was filled with concrete, and the attempt at repair was abandoned. It is 

 altogether likely that tlie entire hill is cavernous to an unusual degree, 

 and that the only way to render the valley side tight would be to expose 

 the rock along this entire side of the pond, and close all of the joints and 

 seams with concrete. At the present time the entire water supply of 

 Bloomington is pumr)ed from the leak under the spillway of the lower 

 pond, and an equal amount is pumped back Into the ponds. That is, the 

 leakage at present amounts to over a million gallons a day. Both of 

 these ponds are locate<l in the Mitchell limestone, the foundation of the 

 dam of the lower iwnd resting on the top of the Oolitic limestone. 



Enough eviden<e has now been cited to prove beyond any (piestion 

 that the general geological conditions in the limestone region are distinctly 

 unfavorable to the imjutunding of water. One corollary to be drawn from 

 this fact is that all towiK wiliiin a rcason.-ible distance (a few miles) of 

 the Knobstone area, sliould utilize the latter for their water-snj)ply sys 

 loms. Where it is necessary to olttain water, if at all, from the limestoni' 

 area, the portions underlain I'V tl'.e Oiilitic limestone or the Harrodsburg 

 limestone should be utilized in jtreference to the area underlain by the 

 Mitchell limestone, and the OJilitic is to be ])referred to the Harrodsburg. 

 If it becomes necessary to utilize the Mitchell area, the following facts 

 should be noted: First, it will be notice<l by any one familiar with the' 

 Mitchell limestone tliat there is a layer or l)cd of rather impervious rock 

 about 50 feet above the base of the formation. This layer serves as the 

 floor of many of the caves of the region, and is the level at which many 

 of the large .springs emerge. Examples of this are the Leonard and Shir- 



