Contact with toxic algae can cause skin irritation, vomiting, diarrhea and other illnesses. Runoff carrying fertilizer, manure and eroding soil can deliver phosphorus and nitrogen to streams and reservoirs, feeding the toxic algae. When toxic algae make them unsafe, the loss is personal as well as economic. State and federal conservation programs should direct more money and technical assistance toward watersheds with repeated toxic algae problems. Toxic algae restricts swimming, boating, fishing, threatens pets and livestock, harms local businesses and can raise drinking-water treatment costs.