Water Quality at Bryce Canyon National Park: Trends, 2006–2021

Sampling on Sheep Creek. NPS.

The monitoring

Streams shape how productive an ecosystem is and how good recreation can be. The National Park Service's Northern Colorado Plateau Network monitors the stream conditions that keep habitat healthy for aquatic life, wildlife, plants and people.

At Bryce Canyon National Park, staff sample three sites about once a month:

Core water-quality measures, fecal bacteria, major ions and nutrients are sampled monthly; trace metals quarterly. Results go to park managers, and the long record shows whether problems are appearing — or whether good water is being kept good.

The park's long-term water-quality stations. NPS.

Findings, 2006–2021

The trends were compared with the State of Utah's water-quality standards.

• Water quality remains excellent. The park has kept these waters unimpaired. All three sites may qualify as Category 1 waters, Utah's highest level of anti-degradation protection.
• Occasional E. coli. Infrequent but continuing Escherichia coli exceedances at Sheep and Yellow creeks coincided with trespass livestock — a case for regular fence maintenance along the park boundary.
• Warming. Minimum and maximum air temperatures rose while precipitation stayed highly variable, and water temperatures rose in Sheep and Yellow creeks.
• Less flow. Sheep Creek's flow fell over several periods, and Yellow Creek's higher flows declined. Warmer air driving more evapotranspiration, and perhaps less snowmelt, is likely to reduce flows further.
• Mossy Cave holds up. Despite more visitors along Water Canyon and the Mossy Cave trail, water quality at the spring has not changed.

Other statistical trends were mostly small and likely ecologically negligible; some may reflect new instruments and better quality control rather than real change.

Selected trends (↑ rising, ↓ falling, — no trend; share of samples exceeding a standard in brackets):

Most trace metals — aluminum, cadmium, chromium, copper, iron, lead, mercury, nickel, silver and zinc — were too rarely detected at any site to analyze for trends (more than 50% of results below detection), and exceeded standards in 0–4% of samples. Trends in major ions such as calcium, chloride, potassium and sodium varied by site.

Spring water and irrigation water run through Water Canyon. NPS.

Recommendations

To keep these waters unimpaired, managers could:

• check and maintain fences along active grazing allotments on the boundary;
• start a springs-monitoring program to track bedrock-aquifer supplies and quantify spring flow for water-rights hearings;
• support hydrogeologic studies mapping groundwater aquifers and their flow paths;
• work with Utah on groundwater-protection zones against development that could affect the park's springs;
• make watershed management a priority, with proactive fire risk reduction, and name watershed protection as a goal of fire management and suppression plans;
• gather more data — higher-frequency measurements linking groundwater, precipitation and flow, watershed measures such as vegetation cover and shading, and aquatic insect sampling — to understand what drives the trends.

Sources

Based on "Trends in Water Quality at Bryce Canyon National Park, Water Years 2006–2021," Northern Colorado Plateau Network, National Park Service, summarizing R. Weissinger's report; a work of the United States government in the public domain.