Dallas receives its water supply from two main sources, the Elm Fork of the Trinity River and White Rock Lake. The water from Elm Fork is treated at the Turtle Creek plant and the water from White Rock is treated at the White Rock plant. Turtle Creek also receives some of its supply from Bachman's Dam which is not connected with Elm Fork and has a capacity of 600 million gallons. The water at Elm Fork is impounded in three reservoirs. The smallest impounds 168 million and the largest 440 million gallons. White Rock Lake was formed in 1912 by building a dam across White Rock Creek, and holds about six billion gallons. The White Rock supply is held as an auxiliary supply, used mainly in summer when the consumption is heavy, also at other times if deficient rainfall causes the supply to run low at Elm Fork, and also occasionally when the Turtle Creek plant is closed down for repairs. The White Rock Purification Plant was completed in March, 1923. Previous to this White Rock had been used only in the fall of 1922, when sedimentation and chlorination were used. There was some doubt as to the advisability of building a purification plant at White Rock as the prolific growth of algae kept the water tasting foul during certain portions of the year. As the Elm Fork supply was becoming deficient and no other supply was available for immediate use, it was necessary to use the White Rock supply regardless of taste and odor characteristics. From the beginning of the operation of the plant a slight taste and odor were observed, which was popularly assumed to be chlorine in the water. This taste became more and more noticeable up to the 10th of June, when an unusually heavy rain caused an almost complete renewal of the water in the lake. No taste was noticed for