Each year West Denver Trout Unlimited samples water quality at four locations in Clear Creek. Once a year, in the fall, we also sample bug life. This sampling is scientifically rigorous, following the procedures established by the Colorado River Watch program and Colorado Parks and Wildlife. Data is routinely used by the State Water Quality Control Commission when determining water quality standards.
Recently, one of our members, Keith Greenwell, carried out an analysis of our insect sample composition over the past six years. The results were encouraging, if surprising. In Clear Creek, near Mayhem Gulch, populations of mayfly insects have exploded.
It is generally thought that caddis flies are the last remaining insects in a polluted stream, as they are the heartiest. Burgeoning mayfly populations should indicate improving water quality. We decided to test our theory by analyzing our River Watch sample data. This is public information available at https://coloradoriverwatch.org/our-data/
| Measure | AVG | LOW | HIGH |
|---|---|---|---|
| Temperature (Fahrenheit) | 45.8 | 32 | 60.8 |
| pH (acidity/alkalinity) | 7.31 | 6.95 | 7.53 |
| Dissolved Oxygen (% Saturation) | 80.1 | 78.3 | 81.3 |
| Total Alkalinity as mg/L CaCO3 | 32.55 | 20 | 40 |
| Hardness ppm | 96.3 | 28 | 170 |
With the above measures consistent and within acceptable boundaries over time, we decided to focus on dissolved metals. Most dissolved metals concentrations are trending slightly downward over time, including aluminum, copper, potassium, and zinc. For example,
The big decreases were in sulfates and nitrates/nitrites.
Our samples indicate that water quality in Clear Creek is improving. While we are not scientists, we do know one thing. The next time we go to Clear Creek to fish we will be carrying some baetis imitations!