With the help of YSI equipment and technical expertise, the Miami Conservancy District (MCD) in Southwest Ohio is continuously monitoring the water quality of the Mad and Stillwater Rivers near Dayton, Ohio. As major tributaries of the Great Miami River, these two rivers have a significant impact on the overall health of the Great Miami River watershed. In order to better understand and respond to the threats facing the entire watershed, MCD is using state-of-the-art monitoring systems to observe and record real-time data on temperature, conductivity, pH, dissolved oxygen, chlorophyll, blue-green algae, and turbidity levels of these two river systems.

Why focus on turbidity?

Turbidity is an excellent indicator of the overall health of a waterway. An increase in the concentration of suspended solids reduces the penetration of light to lower depths in the water column. This can cause significant impacts to aquatic plant and wildlife populations. Additionally, high turbidity increases the risk that the water may be contaminated with bacterial and viral illnesses, as well as pesticides, heavy metals, and other pollutants.

As part of the Mad and Stillwater water quality monitoring project, MCD retrofitted out-of-use concrete gauge houses to safely house the monitoring equipment, including several YSI 6-series multiparameter sondes. The sondes are contained in a flow-through tank into which river water is continuously pumped and released back into the river. For the turbidity studies, the sondes were equipped with YSI 6136 turbidity sensors, which uses a nephelometer to obtain turbidity measurements. Considered to be the most accurate method to measure turbidity, the nephelometer emits a beam of light and then measures the amount reflected by the particles suspended in the water. Automated wipers ensure that sediment fouling does not compromise the ability of the sonde to collect accurate data. The sondes are connected to YSI EcoNet web-based data collection platforms, which autonomously record water quality data every one or two hours and post it to the publicly accessible EcoNet website.

Not only does continuous turbidity monitoring enable us to get an accurate picture of the overall health of a watershed, it also gives river managers the ability to combine turbidity data with flow measurements in order to estimate sediment transport – especially during rainfall events.

In Ohio and elsewhere, continuous monitoring of turbidity and other water quality parameters is enabling agencies to compare water quality data across watersheds, and pinpoint the most effective locations for conservation measures.