Prevention of Underground Leakage

many basins and river systems of the area, the intermittent, scanty rainfall was stored in vast underground reservoirs, over the lips of which flowed rising streams. The first diversions of these streams took place about 1775. Some 40 years later small rubble masonry dams were built in canyons cut through alluvial material to raise the ground water level and obtain water power for grist mills. Ground water thus salvaged and controlled was conducted in ditches, some lined with burned clay tile, to farm lands several • miles from the source. After the Mexican War water de-