Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ... CHAPTER VI WATERSHED By watershed is meant the area immediately surrounding a water supply so situated that water falling upon it will be directed toward this supply. Drainage area and catchment are other terms sometimes used in this same connection. The watershed is of immense practical and sanitary value in relation to a given water supply. It should not be too extensive, as it would then be difficult to control properly and keep free from pollution. Neither should it be too restricted, for in rocky regions pollution might be absent from the surface, and still find its way by subterranean means to the water supply. It should be uninhabited, as any sort of habitation for either man or animals contributes to pollution by means of their bodily wastes. If inhabited, the buildings should be as far removed from the spring or well as possible and the wastes should be disposed of in such a manner as to preclude the possibility of contamination. The watershed should be uncultivated, as cultivated soil is rich in organic matter which in the process of decay adds substances to the water which are objectionable. A wooded area is also more valuable than an open one, as it conserves the water supply by preventing evaporation. From what has been said before, sand and gravel soil and subsoil are preferable to a rocky or clayey one. Hand in hand with the foregoing requirements of an ideal watershed must go a knowledge of the geologic conditions underlying the area, as favorable conditions may prevail upon the surface and unfavorable conditions be found beneath. Ability to interpret the conditions found by an inspection of a watershed, the "sanitary survey," is of immense practical value and forms one of the members of the trio of examinations which must be...
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