This study will assess water-quality impacts to select rivers that experience heavy recreational use. This study will provide additional water-quality data for the Namekagon (SACN), Platte (SLBE), New (NERI), and Upper Delaware (UPDE) Rivers that can help park managers make decisions regarding current monitoring programs, management plans, visitor use plans, and/or communication plans.

This interdisciplinary study will use multiple lines of evidence that include microbial, chemical, and physical water quality constituents. These lines of evidence are targeted to provide information directly related to visitor use impacts including water impairments (e.g., fecal indicator bacteria), sediment disturbance, and the presence of human-associated chemicals.

The study includes the following goals:

• Evaluate the concentration of E. coli, enterococci, and staphylococci by traditional culture methods and molecular methods at river locations that are frequently used for recreation.
• Determine the abundance of human-related microbial source tracking (MST) markers to gauge the influence of human sources versus wildlife sources on water quality.
• Identify the occurrence and relative abundance of select human-associated pathogen (e.g., shiga-toxin producing E. coli) and antibiotic resistance genes and incorporate these data into a Quantitative Microbial Risk Assessment (QMRA) to estimate human risk with primary and secondary recreational contact.
• Measure suspended sediment below river locations that are frequently used for recreation.
• Determine the presence of UV filters (i.e., sunscreen ingredients) and select pharmaceuticals at locations frequently used for recreation.
• Determine relations between visitor use and bacteria load, MST markers, pathogen and antibiotic resistance gene presence, suspended sediment concentrations, and contaminant presence.