Fish and macro-invertebrate surveys are common methods for assessing water quality, particularly in streams.
The number and types of organisms in these communities can indicate the health of a stream – providing a bigger picture of long-term water quality.
The U.S. Army Corps of Engineers Louisville District, with the assistance of contractors, assessed the water quality of the C.J. Brown and Caesar Creek reservoirs in Ohio through biological studies of the primary tributaries and tail waters, said Zac Wolf, USACE water quality team biologist.
Macro-invertebrates were sampled using the Hester-Dendy sampling technique, in which artificial substrates are placed in the water for six weeks to be colonized by the resident invertebrates, said Jenna Odegard, environmental scientist/wildlife specialist with MAD Scientist Associates, contractor responsible for the sampling. When these samples are retrieved, additional sampling is performed using dip nets.
This supplemental sampling allows for a collection of invertebrates from a wider variety of the habitats present resulting in a more complete accounting of invertebrate diversity, Odegard added. Fish were sampled using an electrofishing rig referred to as “rollerbeast,” that can float in deeper water or be pushed through shallow water on wide, drum-like rollers.
The contractors take samples of the reservoirs’ tributaries, streams and tail waters, Wolf said. They conduct surveys of insects, small crustaceans and fish to evaluate water quality based on the composition of the aquatic community.
“Biological sampling studies are useful to collect data allowing us to gain an understanding of an ecosystem’s function and general health quality,” Odegard said. “Generally, biological studies can provide important baseline data, such as species presence, abundance and diversity. Furthermore, we can evaluate trends such as growth or abundance of organisms over time.”
The biological sampling also benefits the community and environment by calling attention to environmental changes.
“For example, drastic shifts in the biotic community can indicate presence of pollution and highlight concerns for drinking water or fish consumption,” Odegard said. “We can monitor progress, determine and document the success of management decisions that will improve our ability to repeat desirable outcomes.”
Wolf summarized that the goal is to see how healthy the water is flowing in and out of the reservoirs.
“The Corps’ dams have a big impact on the tail waters. If there is poor water quality, then re-evaluation needs to be made as to how the dam operates or what we can do to improve conditions,” Wolf said.
“In this part of the U.S., we have a really rich biodiversity, which many people don’t realize, and many species can be sensitive to numerous types of pollution, including chemicals or other things such as too much sediment in the water. Little things that change the habitat can have big impacts,” Wolf said.
It is important for people to understand that pollution can come from a variety of sources, not just from the stereotypical big factories that individuals think of. Household products used on a daily basis can also have negative impacts on the water quality; therefore, these harmful substances need to be disposed of properly, Wolf said.
“Even if dumped on land, things typically end up back in the water, which we all rely on,” Wolf said.
The C.J. Brown and Caesar Creek reservoirs are important recreationally for many public activities such as fishing, swimming, camping, hunting and hiking. They are also necessary to reduce flood risk in the Great Miami and Little Miami river systems in southwestern Ohio.
“By monitoring invertebrates and fishes in the tail waters and streams surrounding the reservoirs, we can assist USACE in evaluating the health and sustainability of these aquatic resources for the benefit of the environment and enjoyment of the public,” Odegard said.