Posted: 4-16-2004
Spring a good time to remember water quality

 


By Betsy Lydick
Daily News Correspondent
Ludington Daily News

Spring is here and area residents are applying fertilizer to ensure a healthy green lawn, but homeowners need to be careful when selecting fertilizer if they want to keep area waterways healthy.

Biologists say there is a connection between excessive or inappropriate fertilization and weedy lakes.

Fertilizer is one of the many contributing factors to abundant aquatic plant life. Other factors are lawn runoff, farmland runoff, streambank erosion, decomposing organic matter and improperly maintained septic systems, according to Dr. Hamdy Helal, an expert in the field of lake biology.

Limiting the use of phosphorous-containing fertilizers decreases the likelihood that heavy rains will transport phosphorous to inland lakes or rivers.

Curt VanderWall of Turf Care Lawn Services agrees about the potential for water quality problems when using fertilizers.

“Runoff from fertilizers containing phosphorous are a contributing factor to excessive aquatic plant growth in inland lakes and rivers,” VanderWall said. “Phosphorous applied to lawns on or near any body of water or watershed area can wash into lakes and stimulate unwanted aquatic plant growth. It is very important that homeowners do not apply phosphorous to their lawns unless it is absolutely necessary.

“Random soil tests throughout the area have shown that Mother Nature has provided enough phosphorous. Established lawns don’t usually need it, so phosphorous is not a part of our fertilizer mix,” said VanderWall.

Most commercially available fertilizer contains phosphorous, according to VanderWall.

“We had to custom formulate our fertilizer to be phosphorous free.”

When phosphorous is introduced into a lake it can generate several hundred times its weight in aquatic plants.

Most aquatic plants are a normal and beneficial part of the lake’s ecosystem. Directly or indirectly, aquatic plants provide shelter and food for fish and waterfowl that are part of the aquatic ecosystem. Aquatic plants produce oxygen and reduce shoreline erosion by reducing the impact of wind and wave action.

Overabundant aquatic plants can also interfere with lake recreation.

“In the last two or three years I have had a lot of customers complaining about all of the floating weeds,” said Dave Mahannah of the North Bayou Resort and Marina on Hamlin Lake.

Even though an overabundance of weeds is a nuisance for lake users, not all weeds by definition are considered an aquatic nuisance. The State of Michigan defines an aquatic nuisance species as a waterborne, non-native and invasive organism that threatens the diversity or abundance of native species, the ecological stability of impacted waters, or threatens commercial, agricultural, aquacultural or recreational activity.

The spread of invasive species — including aquatic nuisance species — is the fastest growing threat to biodiversity.

“Once introduced, aquatic nuisance species can forever alter the infested lake,” said Helal, director Aquaculture and Natural Resources Institute at West Shore Community College.

Eurasian watermilfoil is an ANS and has been widely documented throughout Michigan. Eurasian watermilfoil forms a dense mat of vegetation, or canopy, at the water’s surface. “The canopy shades and destroys desirable plant species that provide habitat for fish and other aquatic organisms,” Helal said.

The presence of Eurasian watermilfoil has been documented in area lakes.

“It is important to note that the discovery of Eurasian milfoil in Hamlin Lake is very recent,” Helal said. “We knew that it was in other lakes; the summer of 2003 is the first documentation in Hamlin Lake.”

The species Eurasian watermilfoil is difficult to differentiate from other native aquatic plants. Eurasian watermilfoil has slender stems and feathery leaves. “It is almost indistinguishable from native milfoil and many other non-invasive species of aquatic vegetation,” Helal said.

Chemical treatment of Eurasian milfoil is expensive and provides temporary relief. Residents of Hamlin Lake’s Middle Bayou chemically treated the overabundance of aquatic vegetation with herbicides in the summer of 2003.

Helal examined plant samples from the Middle Bayou after the chemical application and found evidence of Eurasian watermilfoil. “Temporarily destroying some of the Eurasian milfoil may have destroyed beneficial aquatic vegetation and probably enhanced the Eurasian milfoil population,” Helal said.

Harvesting Eurasian watermilfoil mechanically would likely increase the population of Eurasian watermilfoil, according to Dr. Helal. Eurasian watermilfoil propagates through broken fragments. New colonies of Eurasian watermilfoil emerge when small pieces are broken off through harvesting or boat movement.

“Boating may be a contributing factor to the spread of weeds,” Mahannah said. “Weeds are in deeper water than they used to be (because of the effect of zebra mussels) and the boat props are cutting up the weeds. Then, the wind carries the weeds that are floating around on the surface and they grow somewhere else on the lake.”

“There are many factors that contribute to an abundance of plants,” Helal said. “Chemical treatment produces more nutrients for the plants because the plants that have been destroyed sink to the bottom. The solution depends upon the type of plant (that is causing the problem),” said Helal said.

Helal has studied the results of various techniques used to control Eurasian watermilfoil. One technique he has observed is the introduction of milfoil weevils into the aquatic environment. Milfoil weevil larvae feed on Eurasian watermilfoil stems and leaves, ultimately killing the plant. When the Eurasian watermilfoil population is destroyed, the weevils lack nourishment and die.

In October 2001, Helal prepared a report about the impact of milfoil weevils on the Eurasian watermilfoil population in Pentwater Lake. Ten thousand milfoil weevil larvae were introduced into Pentwater Lake and marsh during the summer of 1999. After the milfoil weevils were established, Helal said, “there was a sharp decline in the nuisance Eurasian milfoil population.”

Hamlin Township has contracted with Progressive Engineering to conduct an aquatic vegetation survey of Hamlin Lake. The results of the survey will identify the location of significant beds of Eurasian watermilfoil and will provide computer-generated maps indicating the distribution of aquatic vegetation. Based on the findings of the aquatic vegetation study, Progressive Engineering will prepare its recommendations including a discussion of plant control alternatives.

Helal believes that milfoil weevils are a viable option to reduce the Eurasian watermilfoil population in Hamlin Lake. “The Middle Bayou of Hamlin Lake would be an excellent habitat for the milfoil weevil larvae,” Helal said.

“Approximately 740,000 people visit the Ludington State Park annually,” stated Mike Mullen, park manager of the Ludington State Park. “Most visitors at the State Park also enjoy spending time at Hamlin Lake.”

“Overall, people do a very good job of being natural resource managers,” said Mullen. “Following a few simple guidelines can help protect the natural beauty of a very valuable resource.”

Invasive species, such as Eurasian milfoil, have the potential to destroy a priceless resource. “Lakes, such as Hamlin Lake, belong to everyone,” said Kent Gage, president of the Hamlin Lake Preservation Society. “Part-time or occasional lake use can have long term consequences. We all need to take a few extra steps, such as using fertilizers that do not contain phosphorous, to protect our lakes for future generations.”

blydick@ludingtondailynews.com