Located about 90 miles north of Dayton, Grand Lake St. Marys covers 13,000 acres -- making it Ohio's largest man-made lake. Ample opportunities for swimming, boating, camping and fishing have made it a popular destination for tourists and residents alike. Recently, however, recreational activities came to a screeching halt when burgeoning algal populations prompted state officials to post advisories against swimming, wading and inadvertently swallowing the water.

All over the country, there has been an alarming increase in swimming and fishing advisories caused by harmful algal blooms (HABs). Caused in part by nutrient-laden runoff from surrounding residential developments and agricultural land, excessive algal growth can produce toxins can cause liver damage and severe gastrointestinal illness. So when these harmful algal blooms were detected in Ohio's Grand Lake St. Marys, state officials didn't hesitate to reach out to local experts.

Working hand in hand with Ohio-based YSI, The Ohio Department of Natural Resources and Ohio EPA installed a system of automated water quality monitoring stations to track Grand Lake's algae populations. The monitoring stations are located at the four corners of the lake, and provide department staff with real-time water quality data every 15 minutes. Not only has this automated water quality monitoring system saved department staff a lot of time and money, the comprehensive real-time data obtained by these monitoring stations has proven to be far superior to that of manual sampling methods.

While ODNR and Ohio EPA combat the algal growth with concentrated doses of aluminum sulfate, YSI automated water quality monitoring systems are providing the information that will aid water quality managers in precisely targeting these alum treatments. By studying parameters like dissolved oxygen,  pH, water temperature, conductivity and turbidity, water quality managers also hope to gain a better understanding of what conditions trigger an algal bloom to produce the toxins.

Alum treatment is one of many short-term solutions being employed to lessen algal blooms and bring tourists back to the region, but the state also has its sights set on the long term solution. County, state, and federal officials and local farmers are working hand-in-hand within the lake's watershed to reduce nutrient-laden run-off, stabilize eroding stream banks, and restore wetland ecosystems. These public-private partnerships will continue to be the key driver in ensuring that the economic, social and environmental services provided by Grand Lake St. Marys are protected and maintained far into the future.