. Conservation. Forests and forestry. 274 CONSERVATION from precipitation, but is gathered from the surface in part only; another part appearing from seepages and springs after a trip underground. The former we wiU call "flood run-off," the latter "seepage ; Flood run-off is that part of rain or snow fall which remains on or very near the surface, flows directly to swamps, lakes or streams, and imme- diately or in a short time runs away. Following showers, flood run-off raises streams; following prolonged rains or melting snow it occasions high water, which quickly
. Conservation. Forests and forestry. 274 CONSERVATION from precipitation, but is gathered from the surface in part only; another part appearing from seepages and springs after a trip underground. The former we wiU call "flood run-off," the latter "seepage ; Flood run-off is that part of rain or snow fall which remains on or very near the surface, flows directly to swamps, lakes or streams, and imme- diately or in a short time runs away. Following showers, flood run-off raises streams; following prolonged rains or melting snow it occasions high water, which quickly recedes when the rain or melting ceases; and following excess- ive rains or melting, flood run-oif produces great floods. Flood run-oif is thus the most tran- sient, irregular, wasteful and danger- ous part of precipitation. It damaged the people in the United States in eight months, January i to August 31, 1908, $237,000,000. In the year 1907 it occasioned the loss of $118,238,000. In the ten years prior to December, 1906, it cost not less than $1,500,000,000 in goods, buildings, bridges, roads, railroads, and real es- tate, washed away. These losses are net losses; they do not include deterioration of values not actually destroyed, nor do they cover the incalculable, irreparable loss of fer- tile soil from our mountains, grazing lands, and fields. This loss amounts to approximately 1,000,000,000 tons of soil per annum. Nor does the financial loss include the sum of human suffer- ing or the loss to the Nation through lowered efficiency and morale of the citizens who sufifer from floods. Seepage run-ofif stands in direct con- trast to flood run-ofif. It is slow and gradual where the other is quick and spasmodic; it is regular where the other is irregular; it continues when the other fails. The uses of surface waters (crop growing, city water supply, sani- tation, water power, and navigation) depend on reliability and regularity. Hence it is obvious that the works of man should
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