By Steve Foster and Andy JohnsonNovember 14, 2016
Unknown to most people, the Ohio River is home to numerous species of freshwater mussels. Being little known does not mean that they are of little importance to our overall ecosystem. Freshwater mussels are not only an important food source for muskrats, waterfowl and fish but they can filter several gallons of water a day making them an important indicator of water quality. According to the Freshwater Mollusk Conservation Society 300 species of mussels once inhabited North America. Of those 300 mussel varieties, 38 species are now extinct and 77 species are critically impaired. Twenty-seven different species of freshwater mussels are known to exist immediately below the RC Byrd Lock and Dam including federally endangered species (Figure 1).
With an average of nearly 90,000 cubic yards of dredge material annually, channel maintenance needs at RC Byrd Locks and Dam far exceed average Ohio River navigation projects. Due to significant sedimentation below the project, presence of endangered mussels, and the importance of the RC Byrd navigation mission, dredging and disposal operations at RC Byrd require continued scrutiny in order to best meet objectives. For more than a decade, the District has shown an ability to avoid and/or minimize impacts to these mussel beds during dredging operations through an evolution of monitoring capabilities. Additionally, the District has employed the use of steering currents from the RC Byrd dam in order to direct in-water dredge disposal plumes away from endangered mussels (Figure 2). Intense monitoring of environmental factors downstream of the dredge disposal and adjacent to the valuable mussel bed includes turbidity, sedimentation, and dissolved oxygen. Recently, our monitoring platform was upgraded to provide real-time data transmissions to the District in order to monitor the most current environmental conditions on the mussel beds. The use of this advanced monitoring platform with the operation of steering currents for dredging operations is unique within USACE. These innovations have been well received by our partners in other state and federal resource agencies and have allowed the District to continue cost effective in-water disposal operations.
For the protection of these mussels, the gates on RC Byrd Locks and Dam are now being used in ways never intended through the use of steering currents created by alternative gate operations. Acoustic Doppler units were used to map water current direction and magnitude at multiple roller gate operations to direct sediment away from the mussel beds (Figure 3).
When presented with the challenge of monitoring the real-time effects of dredging on the local mussel populations, the USACE reached out to the remote environmental monitoring sector. The challenge was to deliver a robust field deployable sediment deposition and scour platform capable of recording and sending data back to Corps staff. The platform also had to have the capability to communicate with a multi-parameter datasonde delivering Temperature (F), Conductivity (uS/cm), Depth (m), pH, Turbidity (NTU), Diss. Oxygen Saturation (%), and Diss. Oxygen (mg/L).
Aridea Solutions, a small business company in West Virginia, engineered and delivered the WIZARD (Water Intrinsic Zoological Ambient Research Device) Platform. For the project, Aridea furnished a solar powered communication buoy, eight individual SeaTek ultrasonic transducers, substrate monitoring platform, and a multi-parameter datasonde capable of recording and sending data at a minimum of 5 minute intervals (Figure 4). The data is made accessible through the internet via a cellular broadband connection to Aridea's Thinginformer Software platform. The Aridea Solutions WIZARD platform provides an incredibly flexible solution that allows for the collection and aggregation of multiple environmental parameters through a single interface utilizing off-the-shelf sensor technology. Additionally, the entire platform is capable of being deployed without divers in 3 m to 20 m of water on the Ohio River from a boat.
The District recently deployed the WIZARD in October on the Ohio River below RC Byrd Lock and Dam for the initial testing of the technology (Figure 5). The system was designed by the team to monitor sediment deposition and scour, along with ambient water conditions over mussel beds during maintenance dredging by the Waterways Section. Data was collected over the past two weeks and will be analyzed for quality and ways to improve the platform. In 2017, this platform will be used to monitor mussel beds during maintenance dredging at both RC Byrd and CAPT Meldahl Lock and Dams as part of Clean Water Act compliance.