Consideration and Approval of Agreement: Joint Funding Agreement between the U.S. Department of Interior, U.S. Geological Survey and the City of Flagstaff for Monitoring the C Aquifer of the Middle and Lower Little Colorado River Basins.

Ratification of this agreement allows the City to continue as a partner with the U.S. Geological Survey, Navajo Nation, and others, in collecting regional C-aquifer water level and baseflow information. The City has relied upon groundwater within the regional C-aquifer dating back to the 1950's. This water resource has been a critical component of the City's ability to provide its citizens with a reliable, high-quality water supply over the past 70 years and continues to do so. Additionally, in 2005 the City purchased Red Gap Ranch east of the City, intending to pump groundwater from the C-aquifer as a long-term water supply. Partnering with the U.S. Geological Survey in the hydrologic monitoring of this valuable resource facilitates documentation of pre-development conditions.

The City of Flagstaff's annual cost is $17,600 in FY2023-24, $18,400 in FY2024-25, and $19,000 in FY2025-26 budgeted within 202-08-304-1061-0-4226. The Coconino Plateau Watershed Partnership is contributing funds to the program through the City of Flagstaff for $5,200 in FY2023-24, $5,360 in FY2024-25, and $5,520 in FY2025-26 for a total of $71,080 over three (3) years.

Priority Based Budget Key Community Priorities and Objectives Carbon Neutrality Plan Regional Plan

Yes. Council approved a similar agreement on July 3, 2012, May 19, 2015, and November 11, 2017, and October 20, 2020. Council has authorized ongoing financial support since FY13.

• Authorize the signing of the agreement with the U.S. Geological Survey and maintain a collaborative partnership with the U.S. Geological Survey, Navajo Nation, and other partners, in monitoring the C-aquifer.
• Do not authorize the signing of the agreement with the U.S. Geological Survey.

The current C-aquifer monitoring program was established in 2005 as an agreement between the U.S. Geological Survey and the Bureau of Indian Affairs to evaluate baseflow within Chevelon Creek, Clear Creek, and Little Colorado River. The current program extends across the region and includes Wupatki, Flagstaff, Leupp, Chevelon Creek, and springs on the Navajo Reservation north of Holbrook. Data and results from this project contribute to baseline conditions within the C-aquifer before pumping occurs by the City or Navajo Nation at Red Gap Ranch or Leupp, respectively. Long-term aquifer and baseflow information is also important for understanding the aquifer's response to climate-related impacts.

The purpose of the current monitoring program is to establish baseline information for the C-aquifer before significant groundwater development occurs between Flagstaff and Winslow. Staff recognizes the importance of monitoring the C-aquifer in the areas of Flagstaff, Red Gap Ranch, Leupp and Winslow, and is proposing to continue funding this U.S. Geological Survey monitoring program. The objectives of the project are to: 1) establish baseline conditions in the C-aquifer prior to significant additional groundwater development, 2) evaluate baseflow in the Little Colorado River, Clear and Chevelon Creeks, 3) document changes in flow and water quality of the C-aquifer, 4) inventory and characterize spring resources, and 5) summarize data collected and publish a five (5) year data report during FY26.

The work covered under this agreement contributes to Provision No. 3 of the 2011 Stipulation between the City and the Navajo Nation (Superior Court of the State of Arizona, Civil No. 6417), part of which states: "The Parties agree to work cooperatively and in good faith to evaluate environmental impacts, if any, from both the City's pumping of Underground Water at Red Gap Ranch and the Navajo Nation's pumping of Underground Water along the south-western portion of the Navajo Nation." 

The Navajo Nation has been a financial contributor to this data collection effort since 2005. City staff recognized this collaborative opportunity to support the monitoring of the C-Aquifer within a groundwater basin that both parties share. Data from this collection effort was important information input into the first public groundwater flow model developed by the U.S. Geological Survey (U.S. Geological Survey Scientific Investigations Report 2010-5180, 2011). The Northern Arizona Regional Groundwater Flow Model was the base model for evaluating proposed groundwater pumping by both parties in the December 2015 publication "Red Gap Ranch - Leupp Groundwater Flow Model" conducted by Southwest Ground-water Consultants. The collaborative study was funded through a $300,000 grant from the U.S. Bureau of Reclamation to the City.

The total program costs includes contributions from the Bureau of Indian Affairs - Navajo Nation, City of Flagstaff, U.S. Geological Survey, Coconino Plateau Watershed Partnership, Arizona Public Service, and the Arizona Department of Water Resources. 

This work benefits the City of Flagstaff and contributes information useful to the scientific community, universities, and agencies. Research agencies and universities depend on quality time-series data for scientific studies. Because the information collected under this agreement is derived from remote areas of northern Arizona, it can be used to evaluate long-term trends in the C-aquifer system.

Information from the C-aquifer monitoring program is shared with the Coconino Plateau Watershed Partnership on a regular basis and published on the U.S. Geological Survey website at https://www.usgs.gov/tools/c-aquifer-monitoring-program.