Griggs & Walnut Ground Water Plume

Overview

The Griggs & Walnut Ground Water Plume site sits near the intersection of Griggs Avenue and Walnut Street in Las Cruces, New Mexico. The contaminated area covers roughly 2,500 feet wide by 4,000 feet long. PCE, or tetrachloroethylene, was found in Las Cruces municipal water supply wells in 1993. EPA placed the site on the National Priorities List in June 2001, and the agency determined that PCE in groundwater poses an unacceptable risk to human health.

The long-term cleanup plan, chosen in 2007, uses enhanced groundwater extraction paired with air stripping treatment. The City of Las Cruces and Doña Ana County run this system together through a Joint Superfund Project, pulling contaminated groundwater out and treating it to meet drinking water standards. One well, Well 18, was permanently taken out of service in 1996 after PCE levels briefly spiked above the EPA drinking water standard of 5 micrograms per liter. Construction of the full remedy finished in July 2012. Land use restrictions prevent new wells from being drilled in or near the plume area until PCE levels in the aquifer drop to the drinking water standard. Zoning restrictions also block residential development on the site. As of December 2024, two businesses operate at the location, employing nine people.

EPA completed five-year reviews in 2016 and 2021 to check whether the cleanup continues to protect people and the environment. Vapor intrusion assessments were done in 2023 and 2024. Human exposure is currently under control, with no unacceptable exposure pathways identified. Contaminated groundwater is stabilized, and there is no unacceptable discharge to surface water. The site reached "sitewide ready for anticipated reuse" status in March 2021. EPA is working through the Department of Justice to settle questions about long-term operation and maintenance funding.

The third five-year review is underway, started in May 2025 and expected to wrap up by the end of 2026. A public open house was held on September 18, 2025 at the remediation facility at 153 N. Cottonwood Street in Las Cruces. Residents with questions can contact the EPA staff assigned to this site, the New Mexico Environment Department (NMED), or call Las Cruces Utilities at 575-528-3512. Site documents are available at the Thomas Branigan Memorial Library at 200 E. Picacho Avenue in Las Cruces, reachable at (505) 528-4005.