2018-08-24 / Top News

Lake Is Much Clearer, Filtration Plant Finds

By Marley Tucker


Mackinac Island Water Filtration Plant Manager Allen Burt holds a membrane of porous microfiltration threads that filter bacteria and viruses from incoming water. Membranes can last about eight years, even longer when raw water from the lake is relatively clean. Mackinac Island Water Filtration Plant Manager Allen Burt holds a membrane of porous microfiltration threads that filter bacteria and viruses from incoming water. Membranes can last about eight years, even longer when raw water from the lake is relatively clean. Employees of the Mackinac Island Water Filtration Plant this year are seeing a sizeable drop in the levels of turbity, or cloudiness, in the water the plant draws from Lake Huron and treats for consumption on the Island, according to plant manager Allen Burt.

Normal turbidity is about 3 Nephelometric Turbidity Units (NTU) at the plant and the Environmental Protection Agency says filtered water it exports can’t be higher than 0.3-NTU, which is what workers regularly have measured in water coming into its system before being filtered this year, he said.

It is typical in August to see drastic temperature changes in the water. The plant water intake is about 35 feet below the surface, at the edge of an old riverbed with a sizeable drop-off. It isn’t unusual for the water temperature to drop from 70 degrees to 44 degrees very quickly.

“When we get colder, deeper water coming up, we see that the turbidity is dropping to 0.12,” Mr. Burt said. “It helps our filters run longer without needing to be cleaned. We’re probably 4 degrees colder than we usually are this time of year, but temperature changes so much on the Great

Lakes.”

The plant also has been affected by drought-like conditions during part of the summer.

“From small numbers earlier in the year, we then saw a large amount of water use because it’s been so dry,” he said. “It’s par for the course.”

The Island has had modern water filtration since the plant where Mr. Burt, Roy Bessel, and Eric Cowell work, was built east of Mission Point Resort along M-185. It replaced a system in which an old power plant on the east shore road helped lift water from Lake Huron up the bluff to the Fort Holmes water tank. In that system, which functioned until 1983 with a small steam engine, water was chlorinated, but not filtered.

“Unlike a lot of plants, we do not work 24 hours a day with only three employees,” Mr. Burt said. “We pump to the reservoir until it’s full, and then we are shut down for the evening and gravity feeds the system. In the summer, when there is a lot of water use, we are tied to the plant doing laboratory work and monitoring the systems,” he added. “Generally, when the Island is at its busiest, we aren’t. In the spring and fall, when the Island is starting up and shutting down, we have our hands full with distribution maintenance and heavier filter maintenance.”

The plant initially used sand filters to purify its water, but within a few years, demand exceeded the capacity of that technique, so officials adopted the advanced microfiltration system still used to conform to Safe Drinking Water Act standards. The federal act was passed in 1974 to ensure that standards for drinking water quality were created and enforced by the Environmental Protection Agency (EPA).

After water is pumped through the filters, the filtrate goes into a mixing tank with fluoride before leaving the plant to one of the Island’s two reservoirs, near Fort Mackinac and Fort Holmes. There’s a large generator in the plant to keep the filtration system running during power outages.

Mr. Burt says the Island is blessed to have access to such clean water. In 2018, Mackinac Island’s tap water was the best tasting in Michigan, according to a blind taste test that is conducted at the Michigan Rural Water Association Conference each year.

“We aren’t putting out distilled or reverse-osmosis water. We are working with filtered lake water and the characteristics and the taste of the water depend heavily on the minerals dissolved within,” said Mr. Burt.

His position at the water filtration plant has made him appreciate the quality of Lake Huron water.

“When I speak to other operators about the challenges they have filtering river water or working in the Detroit-Toledo area, where you have warmer, shallower water and more pollutants, I see that it is a different world,” he said.

Mr. Burt has witnessed dramatic lake water changes in the 22 years he has worked at the plant.

“Our shore well, where the pipe brings the water into the plant, is separated by screens to keep fish, algae, and crayfish out of the pumps,” he said. “If you opened the hatch 20 years ago, you’d see hundreds, if not thousands, of crayfish. The water would be slightly cloudy, but you could maybe see the bottom. Now, there are maybe one or two crayfish and it is crystal clear to the bottom - to the point where, if there is no motion going on, you have a hard time seeing the water.”

Zebra and quagga mussels are considered invasive aquatic species in the Great Lakes. They can kill native freshwater mussels, damage manmade water structures, and harm the animals that ingest them. Because of the way they filter water, however, they reduce or eliminate murkiness, Mr. Burt said.

“They took a lot of the microplankton and cloudiness out of the water,” he explained. “The unfortunate side of that is that they take all of the food and starve out other species, which harms the ecosystem.”

As part of ongoing improvements, all bulbs at the plant have been replaced with energy-efficient LED bulbs to save money and provide better light. For about a month now, plant workers have been conducting a metal corrosion study.

“We’ll be running it for probably another month or two to get a baseline,” Mr. Burt said. “Every month, we pull out metal tabs to see how it is going. We are testing black iron, stainless steel, and copper pipes. It never hurts to be proactive with these types of things. Clean water doesn’t always mean perfect, and we don’t expect to find any issues, but it can’t hurt to know more.”

A recent concern for many Michiganders has been discussion among researchers and publicity about a group of chemicals, including perfluoroalkyl and polyfluoroalkyl (PFAs), once used in the aerospace, construction, tannery and textile industries and for firefighting foams. According to EPA regulators, PFAs may be carcinogens.

“We are getting some questions about PFA levels and people are curious about how we test our water,” Mr. Burt said. “It is not something that we usually test for, but the state of Michigan has hired a company to take samples from all water systems in the state by the end of this year. We are probably one of the systems of least concern.”

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