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._ <br />Mathews, Dan <br />To: Clark, David, EMNRD <br />Subject: RE: Irrigation for establishment <br />Thanks slot Dave. What is the annual precip at San Juan? <br />Merry Christmas and Happy New Year! <br />-----Original Message----- <br />From: Clark, David, EMNRD [mailto:david.clark@state.nm.us] <br />Sent: Wednesday, December 14, 2005 2:08 PM <br />To: Mathews, Dan <br />Subject: RE: Irrigation for establishment <br />Hi Dan <br />Our unirrigated sites with that prcp. regime also have some failed establishment once in a while <br />San Juan Mine is the only operation we have that irrigates, and they it do it during the first year <br />and second year, if necessary. Even on irrigated sites, the best revegetation establishment and <br />persistence occurs when we get a couple of above-avg prcp years in a row (about once a decade <br />for the San Juan Basin). <br />Our program has historically argued with San Juan to not irrigate, orjust barely irrigate. We have <br />small mines nearby that did just fine without any irrigation, and met all their approved standards. <br />But with the spotty nature of our moisture, its hard to generalize. In some areas of general failure at <br />San Juan Mine, we can see decent perennial establishment right around the sprinkler head <br />locations, with voids in between (from a high place you can see the pattern of the irrigation layout 10 <br />years after irrigation was conducted). So that makes me think that too little irrigation may be part of <br />the problem. <br />Below is the permit commitiment we have approved at San Juan Mine. I won't say we have it all <br />figured out, but this is the latest version that we are trying. Tim Ramsey at San juan Mine <br />Timoth~C.Ramsey~a.BHPBilliton.com is the best industry contact person in NM for this topic. Good <br />luck and happy Holidays! <br />Irrigation <br />Based on reseaxch conducted in 1974 and 1975 at SJM, irrigation was shown to be a condition required to <br />achieve rapid and successful vegetation stand establishment. Further research has been conducted at both SJM <br />and Navajo Mine to evaluate the effects of imgation water on vegetal performance. In a study coordinated by <br />the Plant Materials Center (PMC) at S1M from 1991 through 1994, several imgation treatments were <br />compared in an effort to improve water use efficiency. This study compared a reduced and standard rate of <br />imgation utilized at SJM and concluded that a reduction in imgation will not significantly affect perennial <br />groundcover in reclaimed areas (PMC, 1994). In another study recently concluded at Navajo Mine,three <br />imgation rates (]ow, medium, and high) were compared to determine vegetal performance over a 4-year <br />period following initial seeding (Buchanan Consultants, Ltd., 1996). This study revealed that vegetal cover <br />was not statistically different among the three irrigation Crea[ments. The results of the two studies suggest that <br />12/14/2005 <br />