Laserfiche WebLink
<br />o tn7? 3 <br /> <br />estimated that it would be practical to clear some 48,000 acres. Since <br />information on the consumptive use by phreatophytes was mostly theoreti- <br />cal and the amount of water that could be saved therefrom was computed <br />on a theoretical basis, a prototype area was selected to determine the <br />practicability of salvaging water by clearing phreatophytes. The area <br />selected lies along both sides of the river between Bernardo and San <br />Acacia Diversion Dam. Gaging equipment was installed to determine the <br />inflow, outflow, and ground water levels of the area with data being <br />accumulated for three full seasons. The 6,400 acres of phreatophytes <br />in the reach were then cleared, and the recording of water data contin- <br />ued, while the area was maintained to prevent regrowth of phreatophytes. <br />Sufficient data have been acquired to show that there has been salvage <br />of water, but the project must be continued to determine "how much <br />waterlt and lIat what cost .11 <br /> <br />In 1962, six evapotranspiration tanks were installed in the Bernardo <br />area to evaluate the water use under various conditions. The following <br />table presents preliminary data for water use by tamarisk in the Bernardo <br />evapotranspiration tanks, Bernardo, New Mexico. <br /> <br />Tanks Depth to Water 1962 1963 1964 1965 <br />1 4.8' 7.5' 3.2' 3.4' 3.2' 3.1' <br />6 4.8' 7.5' 3.1 ' 3.7' 4.5' 3.8' <br />2 3.0' 2.7' 3.4' 3.0' 2.2' <br />3 3.0' 2.7' 3.7' 3.2' 2.4' <br />4 5.0' 2.8' 4.0' 3.7' 3.1' <br />5 5.0' 2.9' 4.5' 4.7' 4.3' <br />Average Dens ity 22% 51% 62% 73% <br /> <br />Public Law 88-594, approved September 12, 1964, authorized the Secretary <br />of the Interior to carry out a continuing program to reduce the nonbene- <br />ficial consumptive use of water in the Pecos River Basin and further <br />authorized the appropriation of funds not to exceed $2~ million for the <br />initial eradication or suppression of saltcedar and other phreatophytes <br />within the area. This project was authorized without the usual feasi- <br />bility report on the basis of testimony presented before the congressional <br />committees. The definite plan studies made subsequent to authorization <br />show that the $2~ million will provide for clearing some 40,000 acres of <br />the more heavily infested areas of a total of 70,000 acres in the reach <br />of the Pecos River between Acme, New Mexico, and Mentone, Texas, exclud- <br />ing the McMillan Delta area. It is estimated that $600,000 annually <br />will be required to operate and maintain the area. The project is fully <br />justified on the basis of water loss prevention. The definite plan <br />report studies indicate an average annual water loss prevention over the <br />next 50 years of about 150,000 acre-feet at a cost of about $4.75 per <br />acre-foot. Assuming the water is used for irrigation, the benefits <br />are estimated to vary from $20.40 to about $58.30 per acre-foot depend- <br />ing upon where the water would be used. Using the above figures, the <br />benefit-cost ratio obtained indicates that removing the phreatophytes <br />is economically feasible. <br /> <br />27 <br />