Support for Colorado Water Quality Monitoring

The Water Quality Control Division (WQCD) of the Colorado Department of Public Health and Environment (CDPHE) is responsible for monitoring state surface, drinking, and ground waters to ensure they are safe and free from pollution. The information collected is used for a wide variety of applications—from informing decisions related to the Clean Water Act, to identifying emerging water quality issues and justifying compliance and enforcement actions. WQCD reports to the public about the quality of state waters and ultimately ensures their protection. WQCD contracted with ERG to provide water quality monitoring support.

ERG has been supporting WQCD in collecting data for four projects to provide CDPHE with essential data for informing management decisions for Colorado waters. During these projects, ERG staff worked with CDPHE to develop a novel tailored data capture interface, replacing paper forms with tablets equipped with Survey123 software integrated with location and photo services.

• Colorado impaired waters stream temperature monitoring. Since 2022, ERG has supported CDPHE’s Colorado Impaired Waters Stream Temperature Monitoring study to better understand how temperature and flow regime vary spatially and temporally in streams across Colorado. ERG has deployed and maintained Stream Temperature, Intermittency, and Conductivity (STIC) data loggers in sections of the Arkansas River, Big Thompson River, Dolores River, Roaring Fork River, and St. Vrain Creek. After initial logger deployment, we revisit streams every three to four months to download stream temperature data and maintain the data loggers.
• Biological and habitat field sampling. ERG has been collecting biological and habitat data utilizing the multi-metric index (MMI) tool for CDPHE’s Watershed Section group. This work supports a provisional study on aquatic life use, which is a component of CDPHE's analysis for 303(d) impaired water bodies. Sampling protocols include use of a flow meter, collection of benthic macroinvertebrates, describing stream channel morphology, visual habitat assessments, periphyton sample collection, water quality sample collection, and streambed particle size measurements.
• Routine water quality monitoring. Since 2023, ERG has collected in-situ water quality data and water quality samples for CDPHE’s Routine Water Quality Monitoring program. Standardized protocols are followed to collect water quality data and water quality samples across Colorado. In 2024, we expanded our support, collecting an additional 150 water samples for E. coli testing for CDPHE’s Total Maximum Daily Load (TMDL) group.
• PFAS in fish monitoring. CDPHE sought to investigate the potential threat of consuming fish from Colorado water bodies containing per-and polyfluoroalkyl substances (PFAS). In 2023, ERG collected fish, sediment, and water samples from Colorado lakes to analyze for PFAS. ERG developed a Sampling Analysis Plan with considerations for handling PFAS samples, sampled six lakes, and had the samples analyzed in a laboratory for PFAS. The data will help guide efforts to develop statewide and site-specific fish consumption guidelines and may be utilized in future assessments.