TRAVERSE CITY, Mich. (AP) — Climate change and invasive mussels may have made Lake Erie a more inviting host for toxic bacteria in recent years, suggesting that ambitious goals are needed for reducing phosphorus runoff that feeds large blooms like the one that forced a temporary tap water shutdown in and near Toledo, Ohio, scientists said Wednesday.

Ever-larger mats of cyanobacteria, commonly known as blue-green algae, have formed on Erie since the early 2000s. They produce microcystin, a toxin that has killed pets and livestock and causes liver damage in humans. The soupy green glop prompted do-not-drink orders for two days in August that affected about 400,000 residents of northwestern Ohio and southeastern Michigan.