SEVERAL foreign plant species are posing a threat to the health of the Collie River according to local environmentalists.
The grass, although not declared a noxious weed, was introduced into the region in the early 1900s and is out of control, creating a threat to the environment and has become a declared weed which could soon dominate the banks, allege the environmentalists.
Pampas Grass starts to take control by dominating native flora and fauna until it has established itself in plague-like proportions.
Not only are the natural flora and fauna taken over but the grass also impacts on soil structures as the earthworm population, which is essential to the health of the whole environment, is negatively effected.
It is therefore necessary to begin eradicating the Pampas grass before it gets to this point.
Watsonia is another foreign plant introduced many years ago that is also having negative effects on the health of the river bank's environment and beyond.
Parts of the Collie River embankment can be seen covered in Watsonia bushes.
These bushes sterilise the soil and no native vegetation can combat them.
When surrounding trees drop their seeds the Watsonia strangles any future tree growth.
The Watsonia's bulbous base takes up enormous space physically as well as hogging the lion's share of water and nutrients.
Again river banks which once once supported healthy worm beds are no longer able to do so argue the environmentalists.
Previously the Weeds and Waterways advisory committee had tried to get Watsonia declared a noxious weed but without success due to government departments lacking money and the determination to follow through.
While the environmentalists believe the situation is now at the point where Watsonia is now out of control in many parts of the South-West region, Collie Shire Council disagrees this is the situation in the Collie area.
"The Shire has an on-going weed treatment program to eradicate a range of weed species, both declared and non declared," Collie Shire Council chief executive officer David Blurton said.
"The Shire has an on-going weed treatment program to eradicate a range of weed species, both declared and non declared," Collie Shire Council chief executive officer David Blurton said.
"The Shire is already tackling weeds in the Collie River and has had considerable success with treatment of Nardoo in the Collie River.
"The Shire is aware of the infestations of Pampas Grass and Watsonia, and treatment is occurring and will continue on a regular basis.
"Pampas Grass is not widespread and there are less than a dozen plants along the river.
"This weed species is not as invasive as some other weed species, however, the infestations have been identified by the Shire's Weeds and Waterways Committee, and will be treated in due course.
"The Shire also has an ongoing program of eradication of Watsonia, which occurs in September during the plants susceptibility period, and treatment of problem areas will be undertaken in September.
"It is also important to note that treating of weeds along the Collie River needs to be undertaken with some caution to ensure that there are not significant detrimental impacts to this sensitive water environment, and the Shire's weed treatment program follows this precautionary approach in these situations."