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<br />~.) \-- I JCj~ <br />1 <br /> <br />l\) <br />.r\) <br />m <br />~ HYDROSALINITYMONlTORING AND EVALUATION IN THE GRAND VALLEY CRSCP <br />IN COLORADO <br /> <br />ISSUE: <br /> <br />NRCS has conducted hydrosalinity monitoring in the Grand Valley Project of the Colorado River Salinity <br />Control Program for eleven years, at a cost of approximalely $940,000 including staff and equipment, The <br />data collected adequately represents the effect of the salinity control program on irrigated fields, Funding has <br />steadily and significantly declined from early project years, creating staffing pressures to meet both <br />monitoring/evaluation and obligations with participants. Managerial, programmatic, and technical aspects of <br />the project must be considered and kept in balance in order to satisfy all of the stakeholders of the project, <br /> <br />BACKGROUND <br /> <br />The Colorado River Salinity Control Act calls for the Secretary of Agriculture to "provide continuing <br />technical assistance for irrigation water management as well as monitoring and evaluation of changes in salt <br />contribution to the Colorado River to determine program effectiveness," The Natural Resources <br />Conservation Service, formerly the Soil Conservation Service, has met this responsibility since the inception <br />of the program, In the Grand V alley project, NRCS has collected eleven years of hydro salinity data that <br />supports program effectiveness, Data has been collected from 191 monitoring sites on a variety of soils, <br />crops and irrigation systems that exist in the project area, The resulting data, summarized below and with <br />attachments, identifies the effects of the program and it's usability to establish priorities with program <br />participants and other irrigators in the Grand Valley, <br /> <br />Total irrigated acres in the Grand Valley: 57,000 Acres <br /> <br />CROPS MONITORED <br /> <br />Crop Acres in GV %of Irr. AC #M&.E Sites <br />Alfalfa 30,000 53% 63 <br />Corn 14,000 25% 46 <br />S. Grains 4,700 8% 26 <br />'Beans 2~400 4% 9 <br />Orchards 2,300 4% 30 <br />Onions 1,000 2% 3 <br />Grapes 200 <1% 10 <br /> <br />%of M&E Sites <br />33% <br />24% <br />14% <br />5% <br />16% <br />2% <br />5% <br /> <br />The above data shows that the hydrosalinity monitoring sites accurately reflect the crops and the significance <br />of crops grown in the project area, The M&E sites also reflect 94% by acreage of the crops grown in the <br />project, <br /> <br />Approximately 98 % of the irrigation is surface irrigation, the remaining 2 % consists of side-roll and micro- <br />jet sprinkler systems, Monitoring was conducted on 181 surface systems, or 95% of all sites over the eleven <br />year monitoring period. <br /> <br />The monitoring data was used to develop the 1994 monitoring evaluation report which revised salt load <br />reduction goals for the project. Briefly, the revised salt load reduction goals were changed based on the <br />effects of the project on deep percolation, The latest summary of monitoring data continues to support the <br />1994 report that deep percolation is reduced by 3 inches with surface systems and 6 inches with sprinkler and <br />surface systems with surge valves (automated), This information is displayed on two attached graphs "Base <br />Line Data/Monitored Data Comparison" and Unimproved/Improved Data Comparison," <br />