Laserfiche WebLink
<br />~ <br /> <br />~ <br />~ <br />~ <br />.~ <br /> <br />The Grand Valley is underlain ~y Mancos shale formation, and covers <br />a~out 126,000 acres, of which 66,000 acres are irrigated cropland. <br />About 6,000 acres of cropland are not cultivated in anyone year. <br />Irrigation water is o~tained .mostly from the Colorado River, and is <br />delivered to the fields through Federal and private canal systems, <br />involving more than 200 miles of canals and over 500 miles of <br />laterals. <br /> <br />, <br /> <br />3. Salinity In The Grand Valley <br /> <br />The' Grand Valley contributes about 600,000 to 700,000 tons of salt <br />annually to the Colorado River. It is assumed that most of these <br />salts (gypsum, calcite and sodium sUlfate) are leached from the <br />soil and to the underlying Mancos shale, and carried to the river <br />by deep percolation through excess irrigation, and by seepage from <br />water delivery and tailwater collection ditches. seepage losses <br />from unlined canals and farm delivery ditches, tailwater collection <br />ditches, and deep percolation from field irrigation.are co~sidered <br />to ~e the major sources of water that carries salt to the river. <br />Salt loading is the major cause of salinity increase. in the <br />Colorado River and has caused water quality problems for downstream <br />water users. <br /> <br />\50 4. Climatic Conditions <br /> <br />Climatic conditions vary in different parts of the Grand Valley and <br />there is difference in temperature and precipitation between the <br />east and west end of the valley. In general, the area has hot. <br />summers, mild winters, and a high percentage of sunny days. The <br />hottest temperatures occur in July and August and can exceed 100 <br />degrees. for several days. The coldest temperatures occur in <br />January and February and. readings below zero .are not. unusual,. The <br />climatic summary for the Grand Junction area is presented in' <br />Appendix A. Average monthly temperatures and precipitation since <br />the M&E program started are provided in this Appendix table. The <br />average growing season varies from 154 days to 190 days ini <br />different parts of the Grand Valley. . . ! <br /> <br />~ ~ <br /> <br />I <br />The Grand Valley has an arid climate and receives ~etween8 to 10 <br />inches of moisture annually, depending on the area. 1993 was <br />wetter than normal and averaged a~out 12 inches. The months of <br />January through May, and October, had above average precipitation <br />and delayed planting and harvesting (refer to climatic summary in <br />Appendix A}i June, July, and September were dry. Extreme cold <br />temperatures did not occur in February like in the past. <br /> <br />3 <br />