US Army Corps of Engineers
Pittsburgh District

It’s all about the water levels

Published Oct. 23, 2019
April showers might have brought May flowers, but this summer’s warm weather brought a different kind of bloom to reservoirs. The Pittsburgh District environmental team focused its efforts to identify harmful algae blooms and conducted testing throughout the Mahoning River Watershed.

April showers might have brought May flowers, but this summer’s warm weather brought a different kind of bloom to reservoirs. The Pittsburgh District environmental team focused its efforts to identify harmful algae blooms and conducted testing throughout the Mahoning River Watershed.

April showers might have brought May flowers, but this summer’s warm weather brought a different kind of bloom to reservoirs.

The Pittsburgh District environmental team focused its efforts to identify harmful algae blooms and conducted testing throughout the Mahoning River Watershed.

The testing was part of a larger strategy to combat harmful algae blooms, also known as HABs, throughout the district watershed.

But what is special about this alga and what makes it dangerous?

The answer comes from Rose Reilly, district biologist.

“Cyanobacteria, or blue-green algae (BGA), are naturally occurring phytoplankton, which is found in freshwater ecosystems around the world,” explained Reilly.

Higher concentrations of algae can result in a bevy of negative side effects for people, ranging from skin reactions to liver and nervous system damage.

Testing the level of BGA gives the Corps an opportunity to identify new blooms and locations of potential issues. The testing is a necessary component of the strategy and key to understanding what conditions make these blooms more likely.

”In order to grow, BGA needs food, that is, high nutrient loads (nitrogen and phosphorus); sunlight; warm temperatures; and pooled, calm waters with long storage retention times,” Reilly explained.

Berlin Lake, which has been following a deviation from the standard guide curve, showed a positive HAB result during July. The record-high precipitation levels that occurred this year carried high nutrient and sediment loads into district reservoirs, and this along with maintenance of a higher pool elevation at Berlin Lake, likely contributed to the development of a HAB in the lake.

Once identified, the district’s HAB response plan, which involves mitigating steps like notifying and supporting the state dealing with the HAB, was activated. The team engages public stakeholders and conducts follow-up water quality monitoring on a weekly basis until data shows that BGA levels have fallen below thresholds for two consecutive weeks.

Reilly said while the process, “… cannot control the nutrient loads to our reservoirs or the weather, but we do have some control over reservoir operations.”

The longer the reservoirs store water, the more likely it is that BGA can grow and create a condition for HABs.

In 2012, the district developed a HAB response plan to reduce human health risks associated with exposure to algal toxins in our reservoirs. The district plan follows the guidelines published by the World Health Organization for safe levels of exposure to BGA.

So, what can you do?

There is a number of solutions. Firstly, always take caution when swimming, wading or allowing pets’ access in waters that are posted for HABs, are green or discolored, or have a thick surface scum or sheen. It is important to keep in mind that pets are particularly susceptible to exposure to HABs because they are often completely immersed in algae laden water. They also drink lake water and then clean themselves, which can allow large amounts of toxins to enter their systems.

The Corps of Engineers, Pittsburgh District owns and operates 16 multipurpose reservoirs located in the headwaters of the Ohio River Basin, and 23 locks and dams located on the Allegheny, Monongahela, and Ohio Rivers. We are responsible for recreation and land, water, and natural resource management at our projects and also the health and safety of those who recreate at them.