Katie Church has yanked so many patches of the pesky invasive European water chestnut this summer, she has dreams about doing it. "I look at the chestnut in the water and [dream of] removing it and making sure everything is clear," she laughs. Church has just finished leading a field team of five summer students hired by the non-profit Invasive Species Centre. The group was tasked with searching, finding and plucking the thick, rooted green invasive aquatic plant by hand along a 30-kilometre stretch of the Welland River, in Ontario's Niagara Region.