Studies & Reports – Projects

SPRNCA RIPARIAN REPORT 2023 (DIXON AND ROBERTSON JANUARY 10, 2024)
Click here for full report.

SPRNCA RIPARIAN REPORT 2023 APPENDICES (DIXON AND ROBERTSON JANUARY 10, 2024)
Click here for full report.

HYDROLOGIC PROTECTION AREAS REPORT (FINAL APR 2001)
Click here for full report.

USPP ADDENDUM TO UNMETERED WELL USE REPORT (APR 2014)
Click here for full report.

UNMETERED RESIDENTIAL AND NON-RESIDENTIAL WELL USE IN THE SIERRA VISTA SUBWATERSHED, ARIZONA (PLATEAU RESOURCES, OCT 2013)
Click here for full report.

USPP DETENTION BASIN INFILTRATION FINAL REPORT (FEB. 2017)
Click here for full report – click here for spreadsheet.

UNMETERED RESIDENTIAL AND NON-RESIDENTIAL WELL USE IN THE SIERRA VISTA SUBWATERSHED, ARIZONA (OCT. 2013)
Click here for full report.

USPP Technical Committee Addendum to the Unmetered Residential and Non-Residential Well Use in the Sierra Vista Subwatershed, Arizona (Plateau Resources, LLC, October, 2013)
Click here for full report

Object-oriented Classification of Impervious Surfaces in Sierra Vista Watershed (SEPT. 2013)
Click here for full report.

NEAR-STREAM RECHARGE AS A TOOL FOR PRESERVING BASEFLOWS ON THE UPPER SAN PEDRO RIVER IN THE SIERRA VISTA SUBWATERSHED OF ARIZONA AND SONORAN SUBWATERSHED OF MEXICO (NOV. 2012)
Click here for full report.

SIERRA VISTA SUBWATERSHED DOMESTIC WELL STUDY (MAY 2012)
The effect of domestic wells on aquifers and streams in Arizona is not well quantified. Because these wells do not require metering, estimates of their pumpage can vary (see Section 3). Nonetheless, the total demand from domestic wells is potentially large and important to water providers, cities and counties as they plan and develop strategies to meet future water needs, including water conservation programs.

Due to the uncertainty in demand, Western Resource Advocates (WRA) contracted Plateau Resources LLC (Plateau) to develop a methodology to estimate the conservation potential of domestic wells in the Sierra Vista Subwatershed (SVS). While this study does not report a total domestic well demand for the region, it does present recent and new household estimates and identifies areas with water conservation potential. Such information may help water managers in the SVS better understand domestic well use characteristics and design and implement appropriate water conservation programs. The methodology developed here is likely also transferable to other areas of Arizona and the western United States.
Click here for summary report / Click here for full report.

PALOMINAS RECHARGE PROJECT
A demonstration project for recharge in the Upper San Pedro subwatershed.
Click here for full report.

SIMULATED NEAR-STREAM RECHARGE AT THREE SITES IN THE SIERRA VISTA SUBBASIN, ARIZONA
This study explores near-stream recharge as a mechanism for sustaining stream baseflows and riparian habitat in the face of continued groundwater-based development in the Upper San Pedro Basin of southeast Arizona through a series of computer simulations. The source of the simulated recharge water is unspecified, but its use is assumed to have no negative impact on the existing basin-wide water budget during the 100-year simulation period.
Click here for full report.

SIMULATED GROUNDWATER AND SURFACE WATER CONDITIONS IN THE UPPER SAN PEDRO BASIN 1902-2105
This study updated and used the published U.S. Geological Survey (USGS) model by Pool and Dickinson (2007) of the Upper San Pedro Basin (USPB) to simulate groundwater and baseflow conditions in the basin from 1902 to 2105 with no adjustments for climate change, but including the best available pumping and recharge data to date. As part of the model updating process, errors in historic pumping and recharge rates in the USGS model were corrected and the impacts of these changes on the transient model’s calibration were evaluated and determined to be negligible. Arizona Department of Commerce (AzDC) population projections for the Sierra Vista sub-basin portion of the model area form the basis for projected pumping rates in the model. Simulated non-mining and non-agricultural pumping rates for 2002-2003 (end of USGS model period) were increased throughout the 21st Century simulation period according to published population growth rate projections. These growth rates were applied to simulated pumping across census county division areas to reflect the spatial distribution of growth anticipated by the AzDC. Projected population growth rates were applied to the latest pumping values within county census block groups to reflect the spatial distribution of growth anticipated by the AzDC. Projected pumping and artificial recharge on Fort Huachuca were based on the most recent Biological Assessment (ENRD, 2006) and input from the Fort’s Environment and Natural Resources Division (ENRD) and Public Works staff. In the new simulation period from 2003 to 2105, net pumping (pumping minus incidental recharge) increases by over 10,000 acre-feet per year (AF/yr), recharge remains constant2 at roughly 22,000 AF/yr, and evapotranspiration (ET) falls from approximately 9,000 to 6,100 AF/yr as a result of declining groundwater levels. By 2105, simulated cumulative storage loss in the model area, including the Mexican portion, exceeds 4.5 million acre-feet (AF).
Click here for full report.

LOW FLOWS IN THE UPPER SAN PEDRO: RECENT TRENDS AND POSSIBLE CAUSES
The first ever observation of zero flow in the San Pedro River at the U.S. Geological Survey’s Charleston streamflow-gaging station on July 6, 2005 has inspired much public and scientific interest in understanding the causes of this event.  It was impossible to conclude that something has fundamentally changed in the aquifer-supported stream system with one event, but since that time the yearly low flows (typically in late June or early July, just before the monsoon onset) have continued to be very low (less than 0.5 cfs) when historical averages have been around 2.5 cfs. The short-term loss of measurable flow is not synonymous with the river bed becoming dry, but it does highlight the continuing reduction in base flow that has been ongoing at that location for decades.
Click here for full report.

Authorization for Feasibility Study
On August 1, 2007 Sen. Kyl and Sen. McCain introduced S. 1929, Sierra Vista Subwatershed Feasibility Study Act, to authorize the Bureau of Reclamation to complete a feasibility study of alternatives to augment water supplies that were identified for further study in the June 2007 Appraisal Report. The legislation also authorizes an appropriation in the amount of $1,260,000 (45%) to Reclamation, establishes the local share of $1,540,000 (55%) and sets a 30 month deadline to complete the study after the date of enactment of the Act. An identical bill will be introduced by Representative Giffords. Click here for a copy of the legislation.