Long-term concentrations of total phosphorus in the alluvial inflow (MW-9) to Cherry Creek Reservoir are more consistent than surface water inflows (CC-10). Note that the alluvial groundwater concentrations consistently hover around the 200 µg/L background phosphorus level in the streams. In WY 2018, the median TP concentration of the alluvial inflow was 190 μg/L.

Median soluble reactive phosphorus (SRP) levels in the Cherry Creek alluvial groundwater (2010–present) were generally similar to median concentrations observed in nearby Cherry Creek surface water; however, there was more spread in the surface water measurements. The data suggest that the TP and SRP concentrations remain relatively consistent between the wells. In contrast, TN decreases as the wells get closer to the reservoir.

Why does Alluvial Water Quality Matter?

Groundwater travels more slowly than surface water to the reservoir. The Authority samples groundwater to investigate the contribution and timing of past and current pollutant loads that originate underground.

• link Monitoring Report: Executive Summary Groundwater Highlights
• link Monitoring Report: Section 3.6 Groundwater
• link Alluvial Aquifer Map
• link Colorado Decision Support System Groundwater Data
• link Monitoring Locations Map