THE DEPARTMENT of Sustainability and Environment is investigating Horsham Rural City Council roadwork that damaged a critically endangered plant site.
Council work on a Natimuk roadside in June damaged a Wimmera rice-flower site.
Department threatened species officer Pauline Rudolph said there were only two known sites for Wimmera rice-flowers in the world, located at Natimuk and Minyip.
Mrs Rudolph said the plant was presumed extinct until 2005 when it was rediscovered on a Natimuk roadside.
Council technical services manager David Eltringham said the department was investigating a council roadwork incident that resulted in site damage.
"We did some road shoulder reconstruction work," Mr Eltringham said.
"There were some of these plants along the side of the road and at that point we were not aware of what they were and unfortunately some were damaged.
"We're working with DSE to reinstate any damage that might have been done and also to ensure any further incidents with this plant won't occur again."
Mrs Rudolph declined to comment on the council roadwork incident.
She confirmed the department was investigating the matter.
She said the plant was presumed extinct from 1901 to 2005, when the plant was discovered at Natimuk.
Mrs Rudolph said the department recorded a second species location at Minyip in 2007.
"These are the only two known populations for the Wimmera and the world," she said.
"This is the most significant roadside for Horsham Rural City Council."
She said the Wimmera rice- flower was listed on the Federal Government's Environment Protection and Biodiversity Conservation Act and on the State Government's Flora and Fauna Guarantee Act.
Wimmera residents gathered at Natimuk yesterday for a Wimmera rice-flower count.
Mrs Rudolph said it was the first official plant count.
"It's a winter flowering plant that takes advantage of autumn rain," she said.
"The plant resurrects itself because of the rain, with new growth and flowers. It's the perfect time to do monitoring."
Mrs Rudolph said late yesterday about one third of the counting had been completed and there were about 1000 plants.