Publications / 2012 Brush Creek Focused Water Quality Assessment

2012 Brush Creek Focused Water Quality Assessment

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Snowmass area stakeholders maintain an interest in understanding the effects of land use and active water resource management on water quality and the biological integrity of aquatic and riparian communities in the Brush Creek drainage. Decision-makers and conservation groups require clarification of these critical relationships in order to guide future resource management actions. Brush Creek was provisionally listed on the State of Colorado’s 2012 303(d) Impaired Waters List for Aquatic Life. Results from benthic macroinvertebrate sampling conducted in 2012 support this designation with three out of four sites indicating use impairment as defined by the State of Colorado.

Brush Creek’s current designation may trigger State action for planning and implementation of water quality improvement measures on the stream. However, the provisional status of the listing indicates that causes of impairment remain unclear. The State will make a final determination of causes of impairment within 10 years of the initial provisional listing (WQCD 2011).

In response to the impaired waters designation on Brush Creek, Roaring Fork Conservancy and Snowmass Water and Sanitation District initiated a study in 2012 to better understand spatial relationships between patterns of nutrient loading and measures of macroinvertebrate community health near Snowmass Village. Results indicated continued impairment of aquatic biology, as assessed by the State’s Multi-metric Index (MMI) methodology. The MMI combines several individual metrics for benthic macroinvertebrate communities into a normalized score which may be compared to healthy reference streams. A sampling location below the wastewater treatment plant produced the only passing score for aquatic life use attainment. Sample sites in the upper watershed indicated low background nutrient levels. Higher concentrations of nitrate and phosphate observed below the wastewater treatment plant rapidly attenuated as the stream exited the developed portion of the resort community and entered range and pasture land in the lower portion of the drainage. Concentrations did not exceed existing state water quality standards for nutrients at any sampling location. Anthropogenic sourcing associated with wastewater treatment plant operations appeared to contribute the majority of nutrient loading to Brush Creek. However, spatial patterns of nutrient loading and macroinvertebrate community health assessments did not indicate nutrient pollution as a primary cause of aquatic life impairment.

Although not assessed by this study, stormwater inputs from the heavily urbanized village area likely influence water quality in Brush Creek during episodic precipitation and runoff events. Turf care and pest management chemicals carried by non-point source runoff may also influence water quality due to the high proportion landscaped streamside land. Studies targeting the magnitude and timing of these water quality impacts can increase understanding of their contribution to water quality conditions and trends.

Roaring Fork Conservancy recommends that local stakeholders on Brush Creek work collaboratively and engage the State to coordinate the planning and development of further assessment activities on Brush Creek. In this way, the process might remain locally initiated and directed, while potentially benefiting from outside resources and expertise. Primary stakeholders on Brush Creek include Snowmass Water and Sanitation District, Town of Snowmass Village, Snowmass Golf Club, Roaring Fork Conservancy, Aspen Skiing Company, and any other interested members of the Roaring Fork watershed community. Achievement of water quality goals on Brush Creek requires a basin-wide approach that jointly considers point- and non-point sources of water quality impairment. Collaborative problem identification and data/information ownership amongst Brush Creek stakeholders can proactively allay potential disagreements about causes of impairment and the appropriate actions required for improvement of water quality conditions.

Funding for this report was provided by Snowmass Water and Sanitation District. Macroinvertebrate sorting, identification and analysis was performed by Timberline Aquatics, Inc. Nutrient data was collected by S.K.Mason Environmental, LLC in conjunction Snowmass Water and Sanitation District. Analysis of nutrient samples was completed at the Snowmass Water and Sanitation District lab. This report was compiled by S.K.Mason Environmental, LLC, Roaring Fork Conservancy, and Timberline Aquatics, Inc.

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Roaring Fork Conservancy

PHONE: (970) 927-1290

PO Box 3349
Basalt, CO 81621

22800 Two Rivers Road
Basalt, CO 81621

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