Surface Water Quality Analysis

Ecological Risk Assessment, Pueblo CO

• ArcGIS Pro • Spatial Analysis • Threshold Modeling • Field Data Integration • EPA Reporting

About the project: 

As part of the broader Pueblo Smelter Superfund effort, Pacific Western Technologies conducted a Site-Wide Ecological Risk Assessment examining the impact of historical smelter activity on the area's surface water. The goal was to determine whether arsenic and lead concentrations in local waterways exceeded safe ecological thresholds and to determine whether cleanup intervention was required.

Surface water locations, sediment sample locations, and residential areas (OU1) and underdeveloped areas (OU2). OU2 was the location of the smelter, which no longer exists, and the property has since undergone changes to revitalize the area.

My work

Establishing the study boundary and control sample I worked with the EPA and field crew to define the Site Wide Ecological Risk Boundary in ArcGIS Pro and mapped all surface water and sediment sample locations within it. A control sample location was established upstream of the former smelter site to provide a clean baseline for comparison with arsenic at 0.612 µg/L and lead at 0.255 µg/L.

Analyzing sample results against thresholds Each sample location's arsenic and lead concentrations were measured against established ecological thresholds:

  • Arsenic: 1.34 µg/L

  • Lead: 0.422 µg/L

I integrated field sample data into the spatial dataset and evaluated each location for exceedance. Locations closest to the former smelter showed the greatest concentration levels which is shown with a clear spatial pattern visible in the final map output.

Deliverable production I produced a final map depicting all sample locations, their measured concentration values, and their relationship to both the control baseline and EPA thresholds. This was delivered to the EPA as a formal project deliverable.

Map shows what surface water locations were sampled and depicts the Arsenic and Lead concentrations. These concentration values were measured against our control sample location values of 0.612 µg/L for Arsenic and 0.255 µg/L for Lead.

If a sample location exceeded the maximum Arsenic and Lead allowance (1.34 µg/L for arsenic and 0.422 µg/L for Lead), the location would require a cleanup.  This testing was used to see the effects the smelter had on the surface water across these different stream locations.

Conclusion

The surface water analysis confirmed that smelter proximity correlated directly with elevated contamination levels in the waterway. By spatially mapping sample data against ecological thresholds and a clean control baseline, this project established the data foundation needed to track ongoing ecological recovery in the former smelter area.