The following article was written by Ed Lentz, Hancock County Extension Educator and edited by Jim Hoorman.

PUTNAM COUNTY — Waterways and lakes have always been important resources for northwestern Ohio. About 11 million people in the USA and Canada use Lake Erie water as their primary drinking source so clean water is a concern. Evidence for this concern was the large algae bloom that occurred in Lake Erie in 2011 but not in 2012. Algae blooms are a concern since some species are toxic to people and they interfere with recreational activities. In smaller bodies of water the algae may deplete oxygen levels as they decay, which may result in fish kills. Algae blooms generally occur in the presence of excess nutrients, especially phosphorus. Phosphorus (P) sources may originate from industrial, municipal, and agricultural systems.

In agriculture, P is required to produce high yielding crops. Phosphorus not used by the crop is generally tied up or trapped by the soil. This tie up generally minimized P loss unless soil leaves the field by water or wind erosion. Farmers have started using reduced tillage and/or cover crops to reduce soil erosion. However, P now remains on or near the surface after application which may result in losses with heavy rain events. About 90 percent of most P runoff occurs during 10 percent of the most intense rainfall events and about 80 percent of the P comes from only 20 percent of the land (Sharpley, 2013). In 2011, heavy spring rains delayed planting until early June and may have contributed to the algae problems.