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What's Clarity?

What is water clarity?

Water clarity is a measure of how clear or transparent water is, indicating the amount of light that can penetrate through the water column. It is an essential indicator of water quality, reflecting the presence of suspended particles such as sediments, algae, and organic matter. High water clarity typically signifies clean, healthy water, while low clarity can indicate pollution or ecological imbalances.

Water clarity matters for several reasons. Ecologically, it affects the health of aquatic ecosystems by influencing photosynthesis, habitat quality, and the overall food web. Clear water allows sunlight to reach deeper, supporting the growth of submerged vegetation, which in turn provides habitat and food for aquatic organisms. For human use, clear water is important for recreational activities like swimming, boating, and fishing, enhancing the aesthetic and economic value of water bodies. Additionally, clear water is crucial for drinking water sources, as it requires less treatment and is generally safer for consumption. Maintaining high water clarity is vital for preserving both environmental health and human enjoyment of water resources.

What was the clarity in Grand Lake before C-BT?

The water clarity in Grand Lake, Colorado, before the implementation of the Colorado-Big Thompson Project (C-BT) was notably high. Historical accounts and studies indicate that Grand Lake had exceptionally clear water with visibility often reaching depths of 30 to 40 feet. The lake's pristine condition was largely due to its natural state, limited human impact, and the absence of significant upstream water diversions or inflows that could bring in sediments or pollutants.

The Colorado-Big Thompson Project, which began in the 1930s and was completed in the 1950s, involved the construction of a complex system of tunnels, canals, and reservoirs designed to divert water from the Colorado River on the Western Slope to the Eastern Slope for agricultural, municipal, and industrial use. As a result of the project, water from Shadow Mountain Reservoir and Granby Reservoir, which contain higher levels of organic material and sediments, began to flow into Grand Lake. This altered the water quality and clarity of Grand Lake, leading to concerns about increased sedimentation, algae growth, and overall ecological impacts.

What causes clarity to decrease

The decrease in water clarity in Grand Lake is primarily attributed to the impacts of the Colorado-Big Thompson (C-BT) Project. The main factors that contributed to the decline in water clarity include:

  • Introduction of Water from Other Reservoirs: The C-BT Project channels water from Shadow Mountain Reservoir and Granby reservoir into Grand Lake. These reservoirs often contain higher levels of sediments, organic material, and nutrients compared to the natural waters of Grand Lake. When this water is introduced into Grand Lake, it increases the turbidity and decreases water clarity.

  • Nutrient Loading: The water from the other reservoirs can carry nutrients such as nitrogen and phosphorus, which can promote the growth of unwanted algae and invasive aquatic plants. Excessive algae blooms reduce water clarity and can also lead to further water quality issues, such as low dissolved oxygen levels when the algae decompose.

  • Sediment Transport: The infrastructure of the C-BT Project, including tunnels, canals, and pumping stations, can stir up and transport sediments across the three lakes. These sediments get deposited in Grand Lake, clouding the water and reducing visibility.

  • Thermal Stratification and Mixing: The operation of the C-BT Project can alter the natural thermal stratification and mixing patterns of Grand Lake, which in turn can lead to changes in the distribution of sediments and nutrients, affecting water clarity.

  • The East Troublesome Fire in October 2020, which burned over 193,000 acres, significantly impacted the water clarity of Grand Lake. The fire burned extensive areas of forest and vegetation, leading to increased runoff carrying sediments, ash, and debris into the lake, which reduced water clarity. The lack of vegetation resulted in soil instability and erosion, with eroded soil washing into the lake and increasing turbidity. Ash and charred material introduced high levels of nutrients such as nitrogen and phosphorus into the water, promoting algae growth and further degrading clarity. Additionally, the fire released chemical contaminants and created hydrophobic soil layers that exacerbated runoff. These changes in the watershed hydrology led to more rapid and intense delivery of sediments and contaminants into Grand Lake, collectively decreasing its water clarity.

Can residents and recreators do anything to contribute to better clarity?

The average person can take several steps to help improve and maintain water clarity in Grand Lake. Here are some actionable measures:

  • Reduce Runoff Pollution: Use environmentally friendly household products to minimize chemical runoff, properly dispose of hazardous materials like paints, oils, and batteries, and limit the use of fertilizers and pesticides on lawns and gardens, as these can wash into the lake and contribute to nutrient pollution.

  • Support Reforestation and Erosion Control: Participate in planting saplings or donate to local reforestation projects to help stabilize soil to prevent erosion.

  • Engage in Lake and Watershed Cleanups: Join community clean-up events to remove debris and trash from the lake and its surroundings, or participate in efforts to remove invasive species that can disrupt the lake’s ecosystem.

  • Promote Sustainable Recreation: Follow best practices for boating, such as using designated launch areas to prevent shoreline erosion. Stay within marked areas to avoid aquatic vegetation and wildlife to maintain the natural balance of the lakes. Clean and utilize boat checkpoints to ensure no invasive species are tagging along on your vessel before launching. Or, consider using non-motorized or low-impact watercraft when possible to reduce fuel and oil runoff.

  • Advocate for Environmental Protection Policies: Support policies and initiatives aimed at protecting water quality and reducing pollution in Grand Lake, like becoming a member of the Three Lakes Watershed Association. Consider writing to local and state government agencies or attend meetings that advocate for stronger environmental regulations and provide funding for conservation projects.

  • Educate and Raise Awareness: Educate others about the importance of maintaining water clarity and the steps they can take to help, or organizations they can volunteer or donate that actively work on advocating for Grand Lake water clarity standards. Follow watershed accounts on social media and share information about the impacts of poor water quality and the benefits of conservation efforts/

Since 2008, the Grand County Water Information Network (GCWIN) has managed lake clarity monitoring in Grand Lake and Shadow Mountain Reservoir. Currently, seven sites are monitored weekly from ice-off to ice-on. The data gathered from these sites is used by the Grand Lake Adaptive Management Committee to evaluate and adapt the operations of the Colorado-Big Thompson Project to improve Grand Lake's clarity. This consistent monitoring is crucial for making informed decisions that support the health and sustainability of these vital water bodies.

It takes a village to vocalize and advocate for change, and every individual can contribute to improving and preserving the water clarity of Grand Lake, ensuring it remains a healthy and vibrant ecosystem for future generations.