Fears rise over the recent resurgence of Cladophora Algae in lake waters and on Door County shores

This is the first in a two-part series on water quality.

Europe Bay, a long wild beach at the tip of the Door Peninsula, has seen its shorelines transformed by dense and stringy algae that covers much of what used to be sandy dunes.

A couple from Chicago who have been coming to Door County with their small children for the past five years described the bay as “beautiful, but not recreational.”

They added that if the algae covered the whole shoreline there was “no way” they would come to swim in this area. “It’s beautiful but the algae is weird,” the father said. “It’s not like it’s seaweed…we were wondering where it came from and what it was.”

Joe Bunda, a Door County native who works at a local pizzeria, said tourists come to the peninsula in large part expecting to enjoy beautiful beaches and water but “they might see the algae and have second thoughts.”

With more than 20,000 beach closings nationwide in 2005 and 200 beaches in two dozen states where samples violated standards 25 percent of the time (one eighth of which were in Wisconsin), issues pertaining to water quality and beach quality have become a local and national priority.

Wisconsin monitors water quality at 113 of its 190 public Great Lakes beaches for bacterial contamination. High priority beaches, both popular and at high risk for contamination, are tested five times a week in order to limit health and safety hazards for visitors. One big risk to water quality is the recent resurgence of cladophora, the smelly green filamentous algae we are finding along our shorelines.

Where is this algae coming from? What is causing its return to our shores?

One possible cause mentioned by the Great Lakes Water Institute for the presence of cladophora in Lake Michigan is the high level of phosphorus found in the water.

According to the institute, high levels of phosphorus are the result of human activity and regional pollution such as lawn fertilizers, poor septic systems, inadequate sewage, and agricultural and detergent waste running off into the lake.

Vicki Harris tests lake water for the Sea Grant Institute. In a presentation called “Use Impairments from Algal Blooms in Green Bay” at the Center of Excellence for Great Lakes and Human Health, she pointed out that phosphorus levels on south and east shores are exceeding recommended levels. Average phosphorus levels were .196 mg per liter from 2000 to 2005 when the target level is between .05 and .1 mg per liter.

Because currents run counterclockwise in the lake, phosphorus spreads throughout the water as it slowly moves up the west shore of Door County to Washington Island where it is then picked up by currents and taken down the east shore of the county as well. According to Christie Rogers, who works for the Department of Natural Resources Water program, much of the phosphate runoff is coming from our shorelines and streams, contrary to popular belief that it’s coming from big cities elsewhere. “This phosphate isn’t coming from Milwaukee,” she said. “It’s coming from us so we need to find local solutions.”

Several experts agreed that the extensive development in Door County and increase in fertilizer use, coupled with a depletion of beach grasses and the presence of more homes along the shoreline could be one of the key reasons that phosphorus levels are rising, including Rogers, Jerry Viste from the Door County Environmental Council, and Bob Bultman of the Soil and Water Conservation Department.

“More development leads to more impervious surfaces and more runoff and is impacting natural aquatic and plant species,” Bultman said.

Wisconsin’s Department of Natural Resources (DNR) strategy for wildlife species of greatest conservation needs, which aims at identifying and protecting those species or areas most at risk, also insists that a major threat to the quality of lake water is the hardening of the shoreline through development and the establishment of artificial shoreline structures that “interrupt the process of long-shore sediment transport that naturally occurs and replenishes sandy beaches.”

So why should we care? What’s so bad about phosphates and how are they linked to cladophora?

Rogers said phosphates are one of the main reasons that the smelly and unsightly cladophora algae is seeing a comeback on Wisconsin shorelines. Cladophora algae feed off of the nutrient as it develops. In the sixties it was first confirmed that abnormal amounts of cladophora algae were the direct result of high phosphorus levels in the water and steps were quickly taken to eliminate the algae by banning phosphate use in detergents. The presence of cladophora declined through the seventies and was almost absent during the eighties and early nineties.

However, recently we have seen a resurgence of cladophora in the Great Lakes because of the increased content and concentration of nutrients like phosphorus entering the lake via streams, rivers and local runoff. The same thing is happening at Lake Winnebago where cladophora is rampant. The lake serves as a receptor for the Fox River and the phosphorus is coming from all the small communities bordering the river, not from the lake itself.

”If all the phosphorus sources were shut off it would take ten years to get normal levels back because this nutrient is not being used or going anywhere,” Viste said.

He also said some municipalities were drawing ground water from water supplies and “shooting it back out into the lake loaded with phosphorus.” He questions why more towns in the area aren’t adopting experimental wetland systems such as the one in Egg Harbor. Such systems are also in place in Petaluma, California and other municipalities. One way to limit nutrient content in water runoff can come from encouraging the development of such experimental wetland environments where vegetation can filter nutrients out of the water before it feeds into the lake. “Vegetation on dunes serves as a protective barrier because it absorbs excess nutrients before they actually reach the lake,” Rogers explained.

Another way to limit phosphate runoff into the lake is to use phosphate-free detergents and fertilizers. The Door County Board of Supervisors showed its support for the adoption of a statewide ban to prohibit the sale and use of lawn fertilizers containing phosphorus in a resolution passed in November of 2006. Although phosphorus is probably not the only reason that cladophora algae is developing so quickly in our waters (some other reasons include low lake levels and the presence of the invasive zebra mussels), by limiting its runoff we can reduce the destructive impact it will have on the lake and on Door County shores.

Note: If you wish to remove cladophora from any shoreline it must be done by hand (shovel, rake, wheelbarrow) and no Department of Natural Resources approval is needed. If you remove the material it must be disposed of in an upland location and cannot be pushed back into the water or in a wetland. For more information click here.

Coming Next Issue: A look at invasive species in and around our shores and the struggle to manage them on the Door Peninsula.

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