As the world population grows, many more people will end up in regions with a shortage of water. So it’ important to ensure that the accessible fresh water is both safe and drinkable. Currently, much of the freshwater around the world is overrun by toxic algae called cyanobacteria or blue-green algae. The algae’s blooms are formed mainly by fertilizer runoff into bodies of water that serve as freshwater drinking supplies. The blooms spread rapidly, producing large quantities of the toxin microcystins in our lakes, streams, reservoirs, ponds, and rivers. If these very tiny molecules get into a water treatment plant, conventional treatment processes are not always efficient in removing these toxins. Polluted water may become much more difficult to treat, and could cause widespread contamination. But, if we know the reservoir is impacted by these toxins, drinking-water operators can adjust their management accordingly. The key to keeping our water safe is to detect and contain the toxins before they ever reach a plant. That is why engineers at the University of Cincinnati are developing a fast-responding bio sensor to detect these harmful toxins to protect our water and our health. Though the team is currently working with Southwestern Ohio issues, they hope to apply this work to large bodies of fresh water like the Great Lakes and other at-risk international lakes and rivers.