TOLEDO, Ohio (AP) — There's a whole network of satellites, underwater robots and scientific tools watching for toxic algae on Lake Erie. But when it comes to predicting where and when harmful blooms will show up on the Ohio's rivers and reservoirs, there's still a lot of mystery.

Researchers now are beginning to look at how to determine which waterways around the state are at the greatest risk and when a crisis could be on the way. Doing that also could point the way to preventing it from happening and provide a model for states around the nation seeing an increasing number of waterways plague...