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<br />!'- <br />C.J <br />en <br />N <br />C,.; <br />o <br /> <br /> <br />Area where Mancos Shale is very close to topsoil <br /> <br />Eventually the salt is left behind in <br />the root zone, or even, in extreme cases, on <br />the surface of the ground. Thus 30,000 acres <br />of the Grand Valley have been lost to <br />production, turned into poor pastures and <br />alkali flats by seepage, evaporation, and <br />a rising water table. Thus it is not just the <br />farmer downstream who suffers but the <br />, <br />people of Grand Valley also, because once <br />rich land has become less valuable for crops, <br />some now suitable only for storing the cast <br />off junk of a civilization. <br /> <br />If that were all there is to the problem, <br />the solution would be simple - don't put too <br />much water on the land. But there is another <br />significant factor indirectly related to <br />irrigation - the ditches and laterals that <br />bring the water to the land. <br /> <br />A gravity system such as that used in the <br />Grand Valley employs large ditches to bring <br />the water from up the river to the area where <br />it will be used. The water is then distributed <br />to the individual users through smaller <br />ditches called laterals. Most ditches and <br />laterals in the Grand Valley are simply dug <br />into the dirt. As the water flows through them, <br />some of it seeps into the soil around them, <br />just as water poured into a flower pot soon <br />disappears. <br /> <br />9 <br />