Pueblo, Colorado has always been a working city. Steel mills, smelters, and railroads built this community on the banks of the Arkansas River. But that industrial heritage came with a cost that’s still being paid: contaminated soil, polluted groundwater, and a Superfund site that’s been on the EPA’s National Priorities List since 2014.
The Colorado Smelter
The Colorado Smelter operated in Pueblo’s Bessemer neighborhood from 1883 to 1908, processing gold, silver, copper, and lead ores. During those 25 years, the smelter released enormous quantities of heavy metals into the surrounding environment through smokestack emissions, slag disposal, and general operations.
The contamination left behind is significant. The EPA’s investigation found elevated levels of lead and arsenic in residential soil across a wide area surrounding the former smelter site. Some soil samples showed lead concentrations many times higher than the EPA’s hazard level of 400 parts per million for play areas and 1,200 ppm for non-play areas.
In 2014, the EPA added the Colorado Smelter site to the National Priorities List, making it eligible for long-term Superfund cleanup funding. The designated area covers approximately 14 square miles of Pueblo’s historic neighborhoods, including Bessemer, Eilers, Grove, and parts of the Mesa Junction area.
The cleanup has been ongoing — the EPA and the Colorado Department of Public Health and Environment (CDPHE) have been testing soil at thousands of residential properties and removing contaminated soil where necessary. As of the EPA’s latest updates, remediation has been completed at hundreds of properties, with work continuing.
From Soil to Water
While the Colorado Smelter Superfund designation focuses primarily on soil contamination, the connection between contaminated soil and water quality is real. Heavy metals in soil can leach into shallow groundwater, particularly during rain events and snowmelt. Lead and arsenic are both water-soluble under certain chemical conditions, and their presence in soil creates an ongoing source of potential groundwater contamination.
The USGS has studied groundwater quality in the Pueblo area and documented the hydrogeology of the Arkansas River alluvial aquifer. Shallow groundwater in areas near historical industrial sites can contain elevated levels of metals and other contaminants.
That said, Pueblo’s public drinking water doesn’t come from local groundwater. The city’s water supply is surface water from the Arkansas River and its reservoirs, treated at Pueblo’s water treatment facility. This is an important distinction — but it doesn’t eliminate all concerns.
Pueblo’s Drinking Water System
Pueblo Water, the city’s water provider, draws from the Arkansas River and the Fountain Creek watershed. The utility operates the Whitlock Water Treatment Facility, which uses conventional treatment processes.
According to Pueblo Water’s Consumer Confidence Reports, the system meets all EPA primary drinking water standards. The utility tests for dozens of regulated contaminants and publishes results annually.
However, several factors make Pueblo’s water quality worth monitoring:
The Arkansas River’s upstream influences: The river flows through the historic Leadville mining district before reaching Pueblo. Leadville’s mining legacy — dating back to the 1870s — left heavy metal contamination throughout the upper Arkansas watershed. The California Gulch Superfund site near Leadville has been under remediation since 1983, and while conditions have improved significantly, the upper Arkansas still carries legacy mining contamination.
Lead service lines: Like many older cities, Pueblo has an aging water distribution system that includes lead service lines connecting some homes to the water main. Even if the water leaving the treatment plant is lead-free, lead can dissolve into water as it passes through these pipes, especially if water chemistry conditions are corrosive.
Pueblo Water adds corrosion control chemicals to its treated water to reduce lead leaching from pipes, as required under the EPA’s Lead and Copper Rule. The utility’s lead testing at consumer taps has generally remained below the EPA’s action level of 15 parts per billion, but any detectable lead in drinking water is worth addressing at the household level.
Disinfection byproducts: Trihalomethanes (THMs) and haloacetic acids (HAAs) form when chlorine reacts with organic matter in source water. The Arkansas River can carry significant organic material, particularly during spring runoff. Pueblo Water monitors these byproducts and has stayed within EPA limits, but they are consistently detected.
Other Industrial Legacies
The Colorado Smelter isn’t Pueblo’s only contamination concern. The city’s industrial history includes:
CF&I Steel (now Evraz Rocky Mountain Steel): The steel mill has operated in Pueblo since 1881 and remains active today. Historically, steel production generated slag, air emissions, and wastewater containing heavy metals and other industrial chemicals. The mill operates under EPA and CDPHE permits governing its current discharges.
The Pueblo Chemical Depot: Located east of the city, this former U.S. Army installation stored chemical weapons for decades. The last of the depot’s mustard agent stockpile was destroyed in 2023 as part of the Chemical Weapons Convention compliance program. While the depot has its own environmental monitoring program, its presence has been a concern for nearby communities.
Railroad operations: Pueblo was a major railroad hub, and decades of railroad activity left contamination from fuel storage, maintenance operations, and material handling at various sites throughout the city.
What the Data Shows
EPA ECHO (Enforcement and Compliance History Online) data for Pueblo Water shows a generally compliant system. The utility hasn’t had significant Safe Drinking Water Act violations in recent reporting periods.
The EWG Tap Water Database identifies several contaminants detected in Pueblo’s water at levels above EWG’s health guidelines but below EPA legal limits. These include:
- Haloacetic acids (disinfection byproducts)
- Trihalomethanes (disinfection byproducts)
- Total chromium
- Arsenic (detected but below the EPA MCL of 10 ppb)
The presence of arsenic at any detectable level in a community with arsenic-contaminated soil from a Superfund site understandably raises concern, even when levels are within legal limits. It’s worth noting that arsenic occurs naturally in Colorado’s geology — not all arsenic in drinking water is from industrial contamination.
What Residents Can Do
If you live in the Colorado Smelter Superfund area:
- Participate in the EPA’s soil testing program if your property hasn’t been tested yet. Contact the EPA’s community involvement coordinator for the Colorado Smelter site.
- Don’t assume soil contamination means your tap water is contaminated — they’re different pathways — but do get your water tested if you have concerns.
- If your children play in yards with untested soil, take precautions recommended by CDPHE: wash hands frequently, remove shoes before entering the house, and maintain grass cover to reduce dust.
For all Pueblo residents:
- Request a copy of Pueblo Water’s Consumer Confidence Report or access it online. Know what’s in your water.
- If you live in an older home, check whether your service line is lead. Pueblo Water should be able to tell you, and they may have replacement programs under the revised Lead and Copper Rule.
- Run your tap for 30 seconds to 2 minutes before using water for drinking or cooking, especially first thing in the morning. This flushes water that’s been sitting in contact with your pipes.
- Consider point-of-use filtration for drinking water. Even a simple NSF-certified carbon filter reduces disinfection byproducts and improves taste.
Water Treatment Options
For households concerned about specific contaminants:
Lead removal: Reverse osmosis systems and NSF/ANSI 53-certified carbon filters can both effectively reduce lead at the tap. This is especially important in older homes with lead service lines or lead solder in plumbing.
Arsenic removal: Reverse osmosis is the most effective residential treatment for arsenic. Specialized arsenic-removal media (like iron-based adsorptive filters) are also available.
Disinfection byproducts: Activated carbon filters effectively reduce THMs and HAAs. Whole-house systems treat all water entering the home; point-of-use systems treat water at a single tap.
Pueblo has earned its resilience through generations of hard work and adaptation. Understanding what’s in the water — and taking straightforward steps to address any concerns — is part of that practical approach to life in a city that’s never been afraid of a challenge.
If you’re concerned about your water quality, a certified water treatment professional can test your water and advise on solutions.