South Adams County Water and Sanitation District v. City and County of Denver

District Court, D. Colorado·Decided August 3, 2026·No. 1:26-cv-00218·Unknown

Opinion

IN THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF COLORADO

Civil Action No. 26-cv-00218-NRN

SOUTH ADAMS COUNTY WATER AND SANITATION DISTRICT,

Plaintiff,

v.

CITY AND COUNTY OF DENVER,

Defendant.

ORDER DENYING DENVER’S MOTION TO DISMISS PURSUANT TO FED. R. CIV. P. 12(b)(6), OR, IN THE ALTERNATIVE, TO STAY (ECF No. 13)

N. REID NEUREITER United States Magistrate Judge

This case involves a cost-recovery action brought by Plaintiff South Adams County Water and Sanitation District (the “District”) against Defendant City and County of Denver (“Denver”) under the Comprehensive Environmental Response, Compensation, and Liability Act (“CERCLA”), 42 U.S.C. § 9607.1 On March 2, 2026, Denver moved to dismiss the Complaint, ECF No. 1, or, in the alternative, to stay or administratively close this matter. See ECF No. 13. The District filed a response, ECF No. 15. Denver filed a reply, ECF No. 19. The Court heard oral argument on April 17, 2026. ECF No. 24. The Court has taken judicial notice of the case file and considered the applicable federal and state statutes and case law. As set forth

1 The parties consented to this Court’s jurisdiction on March 24, 2026. See ECF No. 16. below, the Court ORDERS that Denver’s Motion to Dismiss Pursuant to Fed. R. Civ. P. 12(b)(6), or, in the Alternative, to Stay (the “Motion”), ECF No. 13, is DENIED. I. BACKGROUND2 The District is a special district established and governed under provisions of the

State of Colorado Special District Act, Colo. Rev. Stat. §§ 32-1-101 to 1807, and organized to provide water and sanitation district services to the Commerce City area and nearby areas of Adams County. ECF No. 1 at 2. In 2025, the District delivered “over 3,000,000,000 gallons of drinking water to approximately 75,000 people through over 24,000 connections.” Id. at 4. To meet its customers’ water needs, the District withdraws water from its groundwater wells. Id. at 5. The District owns and operates a drinking water supply system that withdraws groundwater from three wellfields overlying an alluvial aquifer tributary to the South Platte River. Id. The drinking water wells are located south of East 96th Avenue and north of East 60th Avenue in Commerce City. Id. The drinking water

supply system includes eight deep groundwater wells. The District also purchases treated water from Denver Water pursuant to a 1998 lease agreement. Id. The District also owns and operates a drinking water treatment plant close to the wells that historically has provided drinking water treatment services to its customers (the “Klein Treatment Plant”). Id. The plant was not designed or intended to treat “forever chemicals” known as per- and polyfluoroalkyl substances (“PFAS”). Id. at 6.

2 Unless otherwise stated, all factual allegations are taken from the Complaint, ECF No. 1. Any citations to docketed materials are to the page number in the CM/ECF header, which sometimes differs from a document’s internal pagination. The District alleges that Denver has contaminated its water supplies through the ongoing release of certain PFAS, including perfluorooctanoic acid (“PFOA”) and perfluorooctanesulfonic acid (“PFOS”). Id. at 1. PFAS are synthetic chemicals that do not occur naturally and exist in the environment indefinitely. Id. at 3. These chemicals

may present significant risk to human health and the environment even at low concentrations. Id. In May 2024, the Environmental Protection Agency (“EPA”) designated PFOA and PFOS as ‘hazardous substances.’ The rule became effective July 8, 2024. See 89 Fed. Reg. 39,124 (May 4, 2024). The District discovered that its drinking water was contaminated in 2018, when it tested for PFAS, including PFOA and PFOS, in samples drawn from its water wells. ECF No. 1 at 3. The District alleges that the PFAS levels detected in the raw water samples ranged from 24 to 2,280 parts per trillion (“ppt”). Id. The District alleges that, as of the date of filing this lawsuit, “[p]ursuant to the ongoing monitoring . . . testing conducted by the District confirms that PFAS chemicals are still present at high

concentrations in its raw drinking water supplies. For example, in early November 2025, PFOA and PFOS concentrations in certain wells in the District’s Central Wellfield were measured as high as 342.6 ppt PFOA and PFOS, combined.” Id. The District attributes the release of PFAS to a Fire Training Facility operated by the Denver Fire Department. See id. at 7. The facility is owned by and located in Denver, approximately 1 mile south of the District’s southern wellfield. Id. The District alleges that for decades, Denver used Aqueous Film-Forming Foam (“AFFF”) products containing PFAS in connection with training activities at the training facility. Id. Specifically, the District alleges that, “on information and belief, Denver would ignite a building located at the Fire Training Facility training pad known as the ‘Burn House’ and direct firefighting trainees to extinguish the fire using these PFAS-containing firefighting foams.” Id. The Complaint alleges that Denver’s failure to control the foam once deployed has resulted in extensive and ongoing release of PFAS into the environment.

Id. The Fire Training Facility is “hydraulically upgradient” of the District’s drinking water wells. Id. The District explains that “[g]roundwater beneath the Fire Training Facility and the PFAS, including PFOA and PFOS, migrates [sic] in the subsurface downgradient” to the District’s wells. Id. The District states that the contamination from the Fire Training Facility has caused it to “necessarily incur tens of millions of dollars in costs responding to Denver’s contamination of its raw drinking water supplies.” Id. at 8. Specifically, when it first discovered the contamination in 2018, the District instituted a program at the Klein Treatment Plant to treat the groundwater using granular activated carbon (“GAC”) to remove PFAS and ensure that the water quality met regulatory standards and

guidelines. Id. at 9. The District alleges that it “has incurred, and will continue to incur, response costs associated with this intensive treatment program.” Id. The District alleges that it has had to increase the amount of treated water it purchases from Denver Water to mix in with and further dilute and reduce PFAS concentrations in the water supply. Id. Additionally, the District had to develop “a rigorous and extensive water quality monitoring and testing program to ensure that PFAS concentrations in its blended finished water supplies are at acceptable levels. Relatedly, given the imperative for timely testing results and to reduce costs, the District had to procure in-house laboratory analytical capabilities.” Id. Per the Complaint, The District has also incurred, and continues to incur, response costs associated with installing, operating, and staffing its in-house laboratory’s PFAS analytical capabilities. Id. The Complaint also notes significant costs for consulting and legal services incurred in connection with the District’s response to the water contamination. Id. Additionally, the District states that it

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