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Initial Lake Mitchell testing shows effectiveness of SolarBee

As Lake Mitchell’s temperature rises, so do the algae blooms.

And a device known as a SolarBee seems to be helping reduce algae levels.

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After regularly testing the clarity of Lake Mitchell’s water between late May and early September, that’s what Mitchell Parks, Recreation and Forestry Director Dusty Rodiek and a handful of volunteers found out.

“It changed dramatically,” Rodiek said in an interview Tuesday with The Daily Republic. “As the water temperatures increased, the clarity in a lot of areas went to 2 feet or less.”

Rodiek presented the results of the testing at an unofficial meeting of the Lake Mitchell Advisory Committee on Tuesday at the Recreation Center. With several absences, the committee did not have enough members for a quorum.

When Lake Mitchell’s temperature approached 80 degrees this summer, there was an observable impact on algae levels, Rodiek said.

“The clarity decreased at all the sites tested,” Rodiek said. “That’s not at all a surprise.”

Tests were performed in six different areas of the lake, including near the SolarBee — a device meant to keep warm water from serving as a breeding ground for blue-green algae, which thrives in warm, stagnant water.

The SolarBee was placed in a bay near Lake Mitchell Campground on the south part of the lake during the summer, Rodiek said, but the device has since been removed for the winter.

The city purchased the SolarBee in 2010. In total, it cost approximately $27,000 for the SolarBee and the installation into the lake.

The city has made several attempts over the years to reduce algae levels in Lake Mitchell, which is a manmade lake. The testing was done to determine what, if any, affect the SolarBee has had on the algae problem.

“It appears the area around the SolarBee had the best average clarity for the season,” Rodiek said.

Lake Mitchell’s water clarity was measured by submerging a disc into the lake and measuring the lowest depth where it was still visible.

The clarity of the testing site near the SolarBee peaked in late June, with a visible depth of 9 feet. By early August, as Lake Mitchell’s temperature rose, the visible depth at that site was as low as 1.83 feet.

On average, the visible depth at the site near the SolarBee was 4.7 feet, better than the five other sites, none of which averaged better than 3.92 feet.

This is the first summer the city has formally tested the effectiveness of the SolarBee. In previous summers, the city saw some visual improvement in algae in the areas around the Solarbee, but no data was recorded on how well it worked.

“Everybody just thought we would put it in and we would be able to physically see a difference,” Rodiek said.

But when that didn’t happen, Rodiek said, it was determined a plan to test the device’s effectiveness was needed.

In 2011, the SolarBee’s battery was dead, which meant the device wasn’t working for half the summer. The device was placed in Kippes Bay near the Sportsmen’s Club in 2012 and was moved last summer to the location near the Lake Mitchell Campground.

“If we’re going to do this, we need to measure its effectiveness,” Rodiek said. “That’s why we set this up last year.”

In June 2010, when the SolarBee was first installed, city officials said as many as five more could be purchased if the device was successful in removing algae. Despite this year’s testing, that decision is still far from being made, Rodiek said.

“It’s entirely too early,” he said. “I’m not going to make a decision based on a single year’s data.”

Rodiek said the SolarBee will remain in the location near Lake Mitchell Campground next summer, and additional testing will be performed. If the results are similar, the SolarBee could be moved to another location and evaluated again, Rodiek said.

“That will tell us definitively whether or not it’s having an effect,” he said.