I have seen plenty of news articles on the subject but have had no first hand experience with algae poisoning. We do what we can with plantings and fish populations to keep our two ponds as algae free as possible. I do know that there are specific types of algae that are the problem and that not all algae are an issue. Also that the issue arises when there is a "bloom" or explosion in the algae population, so keeping a bloom from occurring can be key. Your county extension agent or local water resource officer might be able to come out and have a look at your local creek and see if you have anything to be concerned about.