Secchi Disc Update 6/27/2025

My apologies to those who attended the Let’s Make it Clean Not Green meeting on June 26, 2025. I incorrectly reported the June 15 Secchi reading as 3.41 meters; the correct reading was 3.14 meters.

The latest Secchi Disc reading taken on June 27, 2025, shows 3.40 meters (approximately 11 feet), indicating an improvement in water clarity.

Temperature Update
The lake continues to warm, and the surface temperature of the lake has increased by 1°C compared to the same time last year. While we've experienced a few hot days with temperatures over 90°F, we've also had some cool nights dipping into the low 50s. The lake is warming, but on average the temperature increase is only 0.1°C compared to last year for the.

Please note: Temperature readings at the 12-meter (39.4 ft) depth are no longer being recorded, as the lake’s depth has dropped to 37.6 ft at the Midas Point—the deepest location in the lake.

Here are the 6/27/2025 temperatures readings with depth converted from meters to feet and temp converted from C to F.

Dissolved Oxygen (DO) Update 

Dissolved Oxygen (DO) levels continue a gradual seasonal decline as expected (warmer water holds less oxygen) but encouragingly remain higher this year compared to the same period last year.

On June 27, 2025, DO readings at the 9, 10, and 11-meter depths are above 1.0 mg/L, which is an improvement. In 2024, these same depths had already dropped to 1.0 mg/L or below, a condition known as anoxia—where oxygen levels are too low to support most aquatic life. This is critical because when DO levels fall below 1 mg/L, phosphorus bound to iron in lakebed sediments is released into the water column. This "internal loading" of phosphorus acts like fertilizer and can fuel algae blooms.

The key takeaway:
DO above 1 mg/L at the lake bottom slows phosphorus release from sediments.

Why This Matters

• DO < 1 mg/L = Anoxia = Phosphorus Release from Iron in lake bottom sediment

• DO > 1 mg/L = Less Internal Phosphorus Loading

This is where Alum Treatment plays a vital role. Unlike iron, aluminum binds to phosphorus in a stable form, even under anoxic conditions. So, even as DO drops later in the season, the phosphorus remains locked up, reducing the risk of algal blooms.