Milfoil, an Unwanted Threat to U.S. Steams

Eurasian milfoil is a delicate looking flora that was once a familiar plant to find in fresh water fish tanks.

Still, It did not stay there. Now it is considered an predatory species that threatens North American fresh water streams, rivers, ponds and lakes.

In its native Eurasian surroundings it is a relatively harmless plant (but still a bit of a pest) but here, out of its normal waters, it takes over and destroys ecosystems, clogs water intakes and power plants, and makes them unwanted for recreational purposes.

A Number Of theories are around that explain its introduction. One is that it caught a ride on the ballast of a ship coming from Europe or Asia. That is a good guess. When they tested ships departing occupied water, 25 percent carried some milfoil with it. The other main theory is it was introduced by individuals throwing out aquarium plants or packing material used to ship live worms.

The most dangerous thing about this plant is that it can adapt to live in almost every kind of aquatic habitat in North America. It can live in the cold of Washington State or the warmth of Florida. From pristine waters of the Rockies to the salty waters of the salt marshes it can expand. To make its life better, nothing seems to like eating it.

Once established it propagates rapidly in waters that range from 2 feet to up to 30 feet, snarling just below the surface and clogging out the native vegetation. Some floras like millet are given small chance to grow, which causes problems because they are a food source for many and a home for small aquatic animals. This matted growth also causes trouble for any mammals or birds that fish for their food. Further more, the huge mats keep the wind from properly aerating the water and choking adult fish as well as helping spawn algae blooms which further exacerbate the problem.

These plants are problematic to individuals as well. Not only does milfoil decrease water quality but the mats make shoreline bathing hopeless. Milfoil hinders fish breeding, which means fewer fishermen. Milfoil is also a problem for boatmen because it can become entangled on the engine, cause risks for water skiers and block navigation hazards from the watermen view.

Residential Areas and businesses are also put at a disadvantage because of this small water flora. Water intakes or over flows can get blocked leading to shortages in some areas and flooding in others. Dykes and electricity output can also be touched if the water plant mats get caught up in the dams.

Milfoil control has been difficult. By And Large poisonous substances are out of the question as they demolish the very ecosystem they were meant to save. Physically removing the plant isn’t fully successful because the bits that break off can form new plants elsewhere. For that reason the large automatic harvesters are only used in the worst cases and then only as a first step. Milfoil has been more successfully removed by vacuum dredging, which can pick up any damaged pieces left behind. A weevil maybe the solution to the milfoil dilemma as it love to eat the water flora and is a natural way to fight the weed.

Milfoil is just one type of unwanted species that has outstayed its welcome; many other unwanted aquatic plants are still thriving across the country. When plants or creatures are introduced outside their natural surroundings, you can’t foresee the implications.