PAG’s hydrologic monitoring and research projects have been a significant part of the Watershed Planning Program since the mid 1980s when research began on Cienega Creek. Since that time, we have conducted a variety of projects within the Cienega Creek drainage as well as nearby surface water systems.

In 2007, PAG received a grant from the Arizona Department of Water Resources, under its Arizona Water Protection Fund program. This two-year project consists of habitat surveys, and groundwater and streamflow monitoring near a large erosional headcut feature that appeared on the creek in 2001.

• Cienega Creek Projects 

Since 1997, PAG has evaluated stable isotope data for water withdrawn from the City of Tucson’s storage and recovery projects located in Avra Valley. These facilities are used to recharge Central Arizona Project (CAP) water, which is delivered to Tucson from the Colorado River. The purpose is to use the stable isotope composition of the pumped water to determine the proportion of CAP water vs. groundwater in the subsurface aquifer.

As recharge continues over time, there is a higher percentage of CAP water mixed with the aquifer’s groundwater. In 2008, PAG stopped working on the Central Avra Valley Storage because the isotope analysis showed that the subsurface CAP/groundwater ratios had stabilized.

PAG is now evaluating the newly activated Southern Avra Valley Storage and Recovery Project (SAVSARP).

• CAVSARP Report 2007 (3MB)

In 2008, PAG completed an investigation of groundwater withdrawals from wells located in shallow groundwater areas of eastern Pima County between 1984 and 2006.  As our region’s population expands and groundwater aquifers become developed, it becomes increasingly important to understand pumping trends for sensitive areas, such as shallow groundwater areas, so that riparian habitats are not compromised.

Shallow groundwater areas have water tables that lie less than 50 feet below ground surface, and they are often demarcated by indicator vegetation, such as mesquite and cottonwood trees. Because these trees depend on groundwater, they become vulnerable if groundwater levels decline. The report includes a series of trend analyses on pumping data from non-exempt wells, but it also provides a general summary of data collected from the exempt wells*. The trend analysis helps identify those areas that have experienced increased or decreased groundwater withdrawals from non-exempt wells over the last two decades.

*Exempt wells are permitted to withdraw up to 35 gallons per minute (gpm), but no pumping data is available for these wells. Non-exempt wells, may pump more than 35gpm, they are required to report pumping volumes to the state.

• Shallow Ground Water (SGWA) Report (1 MB PDF)