Annual report

2025 Water Quality Results

Every year the Association, with help from our lake stewards, tests water quality indicators of our lakes. Almost all of our 2025 water quality results fall within the normal range for each of our lakes, and little has changed from previous years. Two areas stand out as worth a closer look, and we have a plan for each.

How our monitoring program worksExplore the historical data

What stands out in 2025

Chloride

Chloride is naturally very low in our lakes, so when it rises it usually points to human activity. Two lakes, Bitter and Burdock, have chloride levels climbing above what we’ve measured in the past. At Burdock and Tedious (Long), those levels are now high enough that they may be harmful to water fleas — tiny animals that eat algae and help keep our water clear. The most likely sources are road salt and water softeners, which drain into septic systems. This winter we plan to look at how best to monitor these lakes, so we can pinpoint where the chloride is coming from and work to stop it from climbing further.

Dissolved oxygen

In several lakes, the deepest water runs out of oxygen by late summer. This is a natural seasonal pattern, but it matters because low-oxygen conditions can cause the lake bed to release phosphorus — a nutrient that can feed algae blooms — back into the water. To find out whether this is happening in our lakes, we’re looking into purchasing a sampler that would let us collect water from these deep areas and measure it directly.

Full 2025 results

What each indicator tells us, followed by this year’s findings.

Secchi Disk Depth

What is it?

A Secchi disk is used to measure water clarity, which is affected by algae and suspended particles in the water. Clarity helps us understand how much light reaches underwater plants, which helps us understand how deep those plants can grow.

2025 results

All lakes had average Secchi depths that are normal for each lake. Lakes with high transparency (more than 4 m) include Redstone, Little Redstone, Bitter, Burdock, and Tedious (Long). Lakes with moderate transparency (2–4 m) include Pelaw and Coleman.

Phosphorus Concentrations

What is it?

Phosphorus is a nutrient we measure to help monitor the risk of algal blooms. Higher nutrient concentrations mean a higher risk of algal blooms.

2025 results

All lakes had phosphorus concentrations that are normal for each lake. Based on these concentrations, all of the lakes are considered oligotrophic (low-nutrient, clear water), except for Coleman Lake, which is mesotrophic (moderate nutrient levels).

Chloride Concentrations

What is it?

Chloride is measured to help monitor the influence of roads, septic systems, and water softeners on our lakes. Chloride is naturally very low in our lakes, so rising levels are a signal of human activity, and at high enough concentrations it can also become harmful to aquatic life.

2025 results

All lakes had chloride concentrations that are normal for each lake, except for Bitter and Burdock, which continue to have concentrations higher than we have seen historically. These results suggest that road salt, septic systems, or water softeners may be having a measurable impact on Bitter and Burdock lakes. 2025 was the first year we sampled Tedious (Long) Lake, so it’s unclear if the chloride concentrations are rising.

All lakes have chloride concentrations below the national water quality guideline for the protection of aquatic life (120 mg/L). However, Burdock and Tedious (Long) had chloride concentrations that exceed the level believed to be toxic to water fleas (20 mg/L). Water fleas (a type of zooplankton) are important to lake health because they eat algae and can help protect our lakes from algal blooms.

Calcium Concentrations

What is it?

Calcium is an essential mineral that aquatic life needs to stay healthy, so we measure it to help us understand the general health of our lakes. Our lakes are naturally low in calcium, in part due to historical acid rain and forestry, which remove calcium from the landscape and waterways. Calcium is especially important for healthy populations of water fleas and other zooplankton that help control algae.

2025 results

All lakes had calcium concentrations that are normal for each lake. Lakes with moderate calcium concentrations (3–20 mg/L) include Bitter, Burdock, Tedious (Long), and Coleman. Lakes with low calcium concentrations (less than 3 mg/L) include Redstone, Little Redstone, and Pelaw. Pelaw is the only lake with calcium concentrations below the threshold considered healthy for zooplankton (1.5 mg/L).

Dissolved Oxygen Concentrations

What is it?

Dissolved oxygen is a measure of how much oxygen is in the water, which is important for understanding where aquatic animals like fish can live. When there is no oxygen in the water just above the lake bed (sediment), nutrients can be released into the water, increasing the potential risk of algal blooms.

2025 results

Dissolved oxygen concentrations were similar to previous years. Redstone and Little Redstone have high oxygen concentrations from the top to the bottom of the water column. Tedious (Long), Burdock, Pelaw, and Coleman all had anoxic (no oxygen) conditions in the deeper water. Dissolved oxygen was not recorded at Bitter Lake in 2025.

See how the lakes have changed over time

Explore nearly 30 years of phosphorus, water clarity, calcium, chloride and sulphate measurements for all seven lakes.

Open the Lake Health Data Explorer