This report documents the range and the upper limit for background concentrations of radionuclides and radioactivity in soils and river sediments that occur as natural rock-forming minerals and worldwide fallout from atmospheric nuclear weapons tests. Documentation is based on the collection of soil and sediment in northern New Mexico and analyzed for 137 Cs, 238 Pu, 23a240 p U! 90 Sr. total uranium, gross gamma, and tritium. The data used to establish the statistical range and upper limit of background concentration cover a 9-or 13-year period ending in 1986. The knowledge of background levels is necessary to interpret soil and sediment data collected for the annual environmental surveillance report and other reports relating to radionuclides or radioactivity in soils and sediments.

Cover photo: An aerial view of Fenton Hill geothermal site, looking south toward Albuquerque. An Affirmative ActwnlEqual %tunity Employer 30 NOT M I C R O~I L~ COVER This report ums prepared as an account of work sponsored by an agency of the United Stafes Guvernment. Neither The Regents of the Unimity of California, the United States Government w any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibilityfor the accuracy, completeness, OT usefulness of any information, apparatus, product, or process disclosed, or represents that its use mould not infringe primtely owned rights. Reference herein to any specific commercial product, process, or seroice by trade name, trademark, manufacturer, or otherwise, does not n e e y i i amstitute or imply its endorsement, recommendation, or fnwring by The Regents ofthe Unmemty of Gdijbmia, the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or refed those of The Regents of the University of Gdifornia, the United States Govenrment or any agency thereof.

I ICover illustration: The graph illustrates the changes in water levels observed in the test welki in the main aquifer of the Los Alamos area. These changes indicate declines of as much as 35 feet. Water level changes in pumping well fields are discussed in Section V of this report. An Afirmative Acfion/Equal Opportunity Employer

I ICover illustration: The graph illustrates the changes in water levels observed in the test welki in the main aquifer of the Los Alamos area. These changes indicate declines of as much as 35 feet. Water level changes in pumping well fields are discussed in Section V of this report. An Afirmative Acfion/Equal Opportunity Employer

I ICover illustration: The graph illustrates the changes in water levels observed in the test welki in the main aquifer of the Los Alamos area. These changes indicate declines of as much as 35 feet. Water level changes in pumping well fields are discussed in Section V of this report. An Afirmative Acfion/Equal Opportunity Employer