New York, South Carolina, and Washington it has been deemed an invasive species and is illegal to sell. Species Elodea bifoliata H.St.John - Canada (AB, SK), W United States (OR + CA to NM + MN) Elodea callitrichoides (Rich.) Casp. - Argentina, Uruguay Elodea canadensis Michx. - most of United States + Canada Elodea granatensis Humb. & Bonpl. - much of South America Elodea nuttallii (Planch.) H.St.John - much of United States + Canada Elodea potamogeton (Bertero) Espinosa - Chile, Peru, Bolivia, Ecuador Chemical control Chemical methods are ineffective in eradicating Elodea – at best they only slow growth for a season or two. As Elodea spreads into new ecosystems, it experiences rapid growth for 5–6 years and then slows as soil nutrients are used up. Elodea is threatening aquatic environments across Europe. Chemicals may be used in places that cause undue economic concerns, but very few aquatic herbicides are registered for aquatic use in the EU. Fluridone, the most commonly used aquatic herbicide is highly effective against Hydrilla, but only marginally effective against Elodea, especially at lower use rates. Mechanical control The plants can also be removed from lakes and rivers mechanically. They are extracted either by hand or by using rakes, chains, mowing boats or weed buckets. The problem is that through vegetative reproduction via fragments, mechanical removal methods can contribute to the spread of the plant. Torn fragments can be transported downstream or are introduced to new environments via attachment to boats and anchor chains. See also Stormy Lake (Alaska) a lake where Fluoridone was successfully used to eliminate elodea References External links Jepson Manual Treatment Hydrocharitaceae Hydrocharitaceae genera Freshwater plants Aquarium plants