Pueblo, Colorado — a city of roughly 113,000 at the confluence of the Arkansas River and Fountain Creek — has a water quality story shaped by heavy industry, Superfund cleanup, and the realities of water supply in the arid West.
The Colorado Smelter Superfund site, which contaminated soil and groundwater across residential neighborhoods with lead and arsenic, stands as the most significant environmental legacy. But the broader picture includes treatment challenges, infrastructure needs, and the water scarcity pressures facing all of southern Colorado.
The Colorado Smelter: Lead and Arsenic in the Neighborhood
The Colorado Smelter operated from 1883 to 1908 in what is now a residential neighborhood in Pueblo’s Bessemer area. For 25 years, the smelter processed gold, silver, copper, and lead ores — releasing heavy metals into the air, soil, and water.
When the smelter closed, the contamination stayed. Decades of residential development built homes on and near contaminated soil. It wasn’t until the EPA began investigating in the early 2000s that the full scope of the problem became clear.
In 2014, the EPA added the Colorado Smelter site to the National Priorities List (Superfund), covering approximately 13 square miles of residential, commercial, and community land in Pueblo.
Key contamination findings:
- Lead in soil — Concentrations far exceeding EPA’s residential screening level of 400 parts per million (ppm) were found in yards, gardens, and play areas
- Arsenic in soil — Elevated levels across the site footprint, particularly near the former smelter location
- Groundwater contamination — Heavy metals detected in shallow groundwater beneath the site
- Slag deposits — Smelter waste material scattered across the area, continuing to leach contaminants
The EPA has been conducting residential soil removal and replacement across affected neighborhoods — a massive undertaking that involves testing individual properties, excavating contaminated soil, replacing it with clean fill, and restoring landscaping. Hundreds of properties have been remediated, with work continuing.
How This Affects Drinking Water
Here’s the important distinction: the Colorado Smelter contamination primarily affects soil and shallow groundwater, not the city’s public drinking water supply.
Pueblo’s drinking water comes from surface water sources — primarily the Arkansas River, treated at the Whitlock Water Treatment Plant, supplemented by water from the Bessemer Ditch and other rights. The treatment plant draws from sources upstream of the most contaminated areas.
However, the contamination does affect:
- Private wells — Any shallow private wells in or near the Superfund site should be tested for lead, arsenic, and other heavy metals
- Gardening — Growing food in contaminated soil can result in plant uptake of metals. The EPA has issued guidance for residents in the site area
- Children’s exposure — Lead in soil is a major exposure pathway for young children who play in yards and put hands in mouths
Pueblo’s Public Water System
Pueblo Water operates the city’s public water system, serving approximately 100,000 customers. The system draws primarily from the Arkansas River and manages several reservoirs for storage and supply.
According to EPA ECHO data and Pueblo Water’s annual quality reports, the system has maintained compliance with federal drinking water standards. Key monitoring areas include:
- Lead and copper — System-wide compliance with the Lead and Copper Rule. As with all cities built before the 1980s, individual homes may have lead service lines or lead solder
- Disinfection byproducts — THMs and HAAs managed within limits, though Arkansas River water quality fluctuations create seasonal treatment challenges
- Turbidity — Storm events and snowmelt can spike turbidity in the Arkansas River, requiring treatment adjustments
- Uranium and radionuclides — Naturally occurring in some Colorado water sources; monitored and within limits
The Arkansas River: Source Water Challenges
The Arkansas River begins near Leadville, Colorado — itself a Superfund site with extensive mining contamination — and flows through Pueblo on its way to Kansas. The river’s upper watershed carries a legacy of hard-rock mining that has contaminated tributaries with heavy metals for over a century.
While most mining contamination settles out or is diluted before reaching Pueblo, the river’s water quality is influenced by:
- Historic mining — Acid mine drainage from abandoned mines in the upper Arkansas watershed
- Agricultural runoff — Irrigation return flows carry salts, nutrients, and pesticides back to the river
- Urban runoff — Stormwater from Pueblo and Colorado Springs contributes pollutants
- Seasonal variability — Snowmelt in spring brings high turbidity; late summer can bring low flows and concentrated contaminants
Pueblo Water manages these challenges through conventional treatment processes and monitoring, but the variable source water quality requires constant attention.
Water Supply: The Western Challenge
Beyond water quality, Pueblo faces water quantity challenges common across the arid West. The Arkansas River’s flows are heavily allocated — water rights in Colorado are governed by the prior appropriation doctrine (“first in time, first in right”), and competition for Arkansas River water is intense.
Climate change is adding pressure. Reduced snowpack, earlier runoff, and more severe drought conditions threaten the reliability of surface water supplies. Pueblo has invested in storage capacity and conservation programs, but long-term water security remains a concern for all southern Colorado communities.
What Residents Should Know
- If you’re in the Superfund site area — contact the EPA’s Region 8 office to learn about soil testing and remediation for your property. Don’t let children play in bare soil in affected neighborhoods. Wash hands and shoes after outdoor activity.
- Test your water if on a private well — Any private well near the smelter site should be tested for lead, arsenic, and other heavy metals. The Pueblo Department of Public Health and Environment can provide guidance.
- Read the annual CCR — Pueblo Water publishes detailed water quality reports. Review the results for your system.
- Test for lead at home — If your home has older plumbing, a lead test through a certified laboratory gives definitive results about your specific situation.
If you’re concerned about your water quality, a certified water treatment professional can test your water and recommend treatment appropriate to your specific contaminants and water source.
Home Treatment Options
- Reverse osmosis — Effective for lead, arsenic, uranium, and most dissolved contaminants. Recommended for homes with confirmed lead issues
- Activated carbon filtration — Handles chlorine taste, DBPs, and organic chemicals
- Point-of-use arsenic filters — Specialized media designed for arsenic removal, relevant for private well owners near the Superfund site
- Water softeners — Colorado’s water tends to be hard; softening improves aesthetics and protects appliances