Protecting Our Water: Aquatic Life

by Michelle Wind

Michelle Wind, P.E. is an Environmental Engineer with Brown and Caldwell, a consulting engineering company in Denver, Colorado

The Big Thompson River Watershed offers diverse fishing experiences from the cold, fast flowing mountain streams of Rocky Mountain National Park to Lake Estes and down into the canyon to the warmer streams and reservoirs at the base of the foothills. The aquatic life in these watershed fisheries is a beneficial and valuable resource to locals and the recreation industry, but aquatic life includes more than just fisheries.

Why do we need to protect water quality for aquatic life?

Rivers and lakes are often referred to as our land’s circulatory system, which support varied ecosystems that help clean water to support many uses. The aquatic life in these ecosystems is not just limited to fish, but also includes a variety of aquatic insects, such as mayflies and caddisflies. Having an appropriate diversity of fish and insects makes for a healthy stream ecosystem. A stream’s health or integrity can be defined in more than one way, but in general, a healthy stream is sustainable and adaptable.

Protecting water quality to support a healthy balance of aquatic life means more than protecting a good fishing spot. Aquatic life is impacted by both chemical (pollution, for example) and physical (flow or channelization, for example) stressors; some organisms, whether insects or fish, are more tolerant than others of such stressors. Therefore, just looking at the makeup of the organisms can indicate whether there may be water quality or habitat impacts in a stream.

Typically, water quality is evaluated by looking at water chemistry, but the objective of the Clean Water Act is to maintain the “physical, chemical, and biological integrity of the nation’s waters.” The State of Colorado establishes water quality standards to protect beneficial uses, including aquatic life. Standards are based on whether an area is classified as cold water, warm water, or both cold and warm water. For instance, the cold water fisheries in the upper portions of the watershed have different standards than the warm water fisheries in the lower portions of the watershed. In addition to standards for water chemistry, biocriteria are on the regulatory horizon. Biocriteria set the standard for a healthy aquatic ecosystem—indicating the numbers and types of organisms typically found in a healthy ecosystem. The State of Colorado is currently in the initial steps of developing a way to integrate measuring aquatic health into water quality standards.

How does the Big Thompson Watershed Forum protect water quality for aquatic life?

The Big Thompson Watershed Forum identified aquatic life as one of the “Big 5” beneficial uses of waters within the watershed, along with drinking water, recreation, agriculture, and aesthetics. To maintain and expand these uses, the Forum developed with a mission to assess and protect water quality to support uses from which we all benefit.

To achieve water quality that optimizes the beneficial uses, the Forum developed a Watershed Strategic Action Plan to prioritize and focus protection efforts. Through this planning process the Forum identified campaigns to address the following specific pollutants of concern:

• Nutrients
• Sediment
• E. coli bacteria

These campaigns address initiatives that improve stakeholder understanding of these issues, influence land use management and the use of best management practices, and support and promote reasonable water quality regulations. The nutrient and sediment campaigns are both key for protection of aquatic life. Nutrients can be a concern in reservoirs where excessive nutrients can increase algal growth and result in pH changes and lower dissolved oxygen levels. Sediment impacts to aquatic life include, but are not limited to, limiting sunlight penetration in the water, introducing contaminants that attach to sediment, smothering stream bottom insect habitat, and decreasing stream depth, which can increase temperature.

The Forum has also implemented an extensive monitoring and assessment program to track water quality throughout the watershed. Even though the Forum is not directly measuring the fish and insects in the watershed, it is measuring the water chemistry, which plays a significant role in the health of aquatic populations. Through monitoring and evaluation, the Forum is identifying stream segments and reservoirs with water quality issues and the potential sources of water quality impacts. This information enables the Forum to identify and evaluate projects to mitigate impacts.

The Forum is taking a proactive approach to assess and protect water quality, which achieves multiple benefits, including the support of aquatic life.