Which type of lake is known for being clear, deep, and having a structured food chain with low phosphorus readings?

Oligotrophic lakes are characterized by their clarity, depth, and structured food chains. These lakes typically have low nutrient levels, especially phosphorus, which is important for plant growth. This low nutrient environment results in clear waters, as there are fewer algae and plant materials to cloud the water. The structured food chain found in oligotrophic lakes supports a variety of aquatic life, including fish species that thrive in cooler, well-oxygenated waters.

Mesoalpine lakes, while also found in mountainous regions like oligotrophic lakes, may not consistently share the same clarity and depth characteristics across all instances. Eutrophic lakes, in contrast, are nutrient-rich and promote higher plant and algae growth, leading to murkier waters. Brackish lakes, which have higher salt concentrations, are also distinct from oligotrophic lakes in terms of their ecological characteristics. Thus, oligotrophic lakes represent the conditions described in the question.