Water Clarity (Secchi Disk)
Water clarity is one of the most fundamental aspects of lake health because it suggests the abundance of algae and therefore the abundance of nutrients in the lake. In addition, water clarity determines the depth of warming by sunlight and therefore the process of seasonal thermal stratification. Water clarity is measured at the deep spot using a Secchi disk and a view scope.

Lake Profiles
Several parameters are measured at the deep spot in the lake at one-meter depth increments from the surface to the lake bottom.

• Temperature – causes thermal stratification, that is, the layers of upper warm water and deeper cooler water. This layering is a fundamental aspect of lakes that governs many of the important processes that occur over the course of a year.
• Dissolved Oxygen – the amount of dissolved oxygen in the water directly influences nutrient concentrations. When dissolved oxygen in the bottom water falls below 1mg/L (becomes anoxic), the process of internal loading becomes accelerated, meaning nutrients previously trapped in the bottom sediment are released into the water.
• Conductivity (conductance) – measures the capacity of dissolved ions in a fluid to conduct electricity. Conductivity increases with increased dissolved salt content and can sometimes be traced back to anthropogenic inputs from road salting and septic systems.
• Light, pH, and Oxydation Reduction Potential – additional secondary parameters that help determine water quality and lake health.

Lake Samples
In most cases, nutrients are the primary factor used for determining water quality. High levels of the nutrients total phosphorus and total nitrogen lead to an increase in plant and algae growth and a decrease in water clarity.
Water samples are collected at specific depths, usually the top, middle, and bottom of the water column at the deep spot in the lake.

Algae Samples
Planktonic algae are microscopic organisms that are suspended in the water column and, at high concentrations, cause a greenish tint to the water. Algae flourishes in water with high phosphorus concentrations.
Algae samples are collected using a 3-meter integrated sampler. The samples are later analyzed to identify algae species and count the concentration of algae within the sample.