The past 30,000 years of arroyo physiography is being studied with mapping and radiocarbon analysis of fluvial sediments. Hydrologic Monitoring Hydrologic data are essential for monitoring and managing New Mexico's limited water resources. These stations are funded in cooperation with Federal, State, tribal, and local agencies. As early as 1971, mercury concentrations in fish from some New Mexico reservoirs exceeded human-health guidelines. USGS scientists from the New Mexico Cooperative Fish and Wildlife Research Unit are working to determine the source of the mercury contamination.
Airborne mercury is captured by rain drops and deposited on the landscape when it rains.
Gaseous and particle-bound mercury deposition from the air during dry periods might also contribute to mercury contamination. Once in the aquatic food chain, concentrations of mercury may increase 300 fold passing from microscopic plants and animals to fish. Thus, even small amounts of atmospheric deposition of mercury may significantly increase mercury concentrations in fish, with possible implications for ecological and human health. Wildfires also may contribute to mercury loading and availability in reservoirs. Following a fire at the headwaters of Caballo Reservoir, mercury concentrations in reservoir sediments collected near the burned site were greater than those at other reservoir sites.