DEMYSTIFYING MILFOIL

(reproduced by permission of Scott Williams and Roberta Hall, Maine Sunday Telegram, September 9, 2001).

By now, almost all Mainers have heard of milfoil, that nasty invasive plant that threatens to ruin our lakes. But there still seems to be some confusion. Is milfoil native to Maine? If not, how long has it been here?

If so, why are we so worried about it? Is milfoil the only aquatic plant that threatens Maine’s lakes? Much of the confusion may come from the way the term "milfoil" has been used.

"Milfoil" has been the catchword to get the message out about the threat of invasive plants in Maine. There was a "Milfoil" Summit this summer. It appears the term has been helpful in raising awareness.

However, reducing a complex problem to a singe generic term has its downside. The term "milfoil" when used to describe the current threat to Maine’s lakes, fails to provide an accurate picture and could be potentially misleading.

First, several milfoil species are native to Maine lakes. These plants aren’t harmful and, like all native plants, provide benefits to the lake ecosystem, such as habitat for wildlife, protecting water quality by absorbing nutrients and reducing shoreline erosion.

Second, there are numerous non-milfoil plants that are just as likely to invade Maine’s lakes, some even more harmful than Eurasian milfoil (considered to be the most invasive of the milfoils). This list of "unwanteds" would include fanwort, waterchestnut and watermilfoils.

In fact, "watermilfoil" is listed in the plants of Sebago Lake but, without further explanation, is confusing. Sebago’s variety may be taken to be nothing to worry about, but Variable watermilfoil is not native to Sebago, to Maine or even to New England. The plant migrated, by way of human activity, to N.E. from the south and west sometime in the 1940’s. It was first identified in Sebago in the late 1970’s and was likely present in the lake for decades before.

The National List of Plants Species that Occur in Wetlands lists six milfoils native to Maine. Therefore it’s not surprising to find one or more of these in Sebago.

So, variable milfoil isn’t native to Maine, but has been here a long time and still hasn’t taken over that lake. What’s the fuss?

The fuss is: Variable watermilfoil, which grows to a maximum depth of 12 feet, will never overtake a lake like Sebago that has depths exceeding 100 feet. But it can become a significant nuisance in coves and near the shore, interfering with boating and swimming and causing property values to decline. It can take over shoreline previously inhabited by native plants and negatively impact important habitat.

With no baseline data to work with, it’s not known how fast the plant is spreading and how many new colonies are forming each year. The Portland Water District has begun mapping milfoil sightings on Sebago and will expand it’s "Invasive Plant Patrol" efforts.

Sebago is one of the most popular boating lakes in Maine and NE, and given that boats are the primary way these plants get from lake to lake, the invasive milfoil found in Sebago is a potential threat to other lakes.

Perhaps it’s time to come up with a new catchword, other than "Spread the Word, Not the Plant" slogan. When speaking about this issue (and not a specific plant) the term "invasive aquatic plants" works better than "milfoil" in almost all cases. It may not lend itself to catchy headlines as "Milfoil Makes Mess of Maine Lakes!" but give it time. It may grow on you.

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