Airborne Em As A 3-D Aquifer-Mapping Tool

The San Pedro River in southeastern Arizona hosts a major migratory bird flyway, and<br>was declared a Riparian Conservation Area by Congress in 1988. Recharge of the adjacent Upper<br>San Pedro Valley aquifer was thought to come primarily from the Huachuca Mountains, but the<br>US Army Garrison of Fort Huachuca and neighboring city of Sierra Vista have been tapping this<br>aquifer for many decades, giving rise to claims that they jointly threatened the integrity of the<br>Riparian Conservation Area. For this reason, the US Army funded two airborne geophysical<br>surveys over the Upper San Pedro Valley, and these have provided us valuable information on the<br>aquifer and the complex basement structure underlying the modern San Pedro Valley.