Another exotic species is causing concern, this time in the Northeastern part of the state. Curly leaf pond weed has been in Minnesota since the late 1800's but a warm spring has boosted its population on lakes near Biwabik, Minnesota. Wendy Crowell, of the D-N-R's Eurasian water milfoil program, answered questions on the nusiance weed at meeting last night sponsored by the Cedar Island Lake Association. She says curly leaf pond weed has a distinct look: