ERDC science helps USACE districts ease time-of-year dredging restrictions

U.S. Army Engineer Research and Development Center
Published July 12, 2021
ERDC science helps USACE districts ease time-of-year dredging restrictions

In the field on the James River, Dr. Matt Balazik, a research ecologist with the U.S. Army Engineer Research and Development Center’s Environmental Laboratory, stays as close as possible to the cutterhead dredger, Lexington, to monitor Atlantic sturgeon and their responses to dredging. Balazik’s research is demonstrating that dredging has no impact on spawning sturgeon and may lead to relaxed time-of-year restrictions on dredging. The large boat on the right, Asia Spirit, is a cargo ship using the federal navigation channel.

ERDC science helps USACE districts ease time-of-year dredging restrictions

Dr. Matt Balazik, a research ecologist with the U.S. Army Engineer Research and Development Center’s Environmental Laboratory, hauls an Atlantic sturgeon on board his boat on the James River in Virginia to evaluate the fish’s health for tagging. Balazik is researching Atlantic sturgeon for the Norfolk District to assess the impact of dredging on the fish, a protected species under the Endangered Species Act.

It was when he was a graduate student at Virginia Commonwealth University that Dr. Matt Balazik, a research ecologist with the U.S. Army Engineer Research and Development Center’s Environmental Laboratory, began intensely studying Atlantic sturgeon, its populations now listed as either threatened or endangered under the Endangered Species Act.

His research has now spanned 14 years and is focused on providing a better understanding of how dredging affects the environment — whether it’s water quality or fish behavior during spawning migrations.

“Restrictions within most waterways are usually for migrating fish,” Balazik said. “Some put in place in the ‘70s or ‘80s were not necessarily based on science. We are collecting data in field settings to get a better understanding of what is actually happening around active dredging projects.”   

The restrictions Balazik refers to are time-of-year dredging restrictions or dredging windows — periods when dredging is prohibited. They were developed by agencies based on what was known about the particular species under the purview of each agency and are implemented in coordination with the U.S. Army Corps of Engineers. In the case of Wilmington and Norfolk Districts, dredging windows were established in relation to Atlantic sturgeon spawning and migration.

Balazik and his team consider each unique situation and then either gather existing data or obtain new data to see whether the science shows the restriction is necessary; if not, armed with the data, the district works to remove it.

Emily Hughes, a biologist at Wilmington District, describes how Balazik is testing water quality in the Wilmington and Morehead City Harbors to facilitate the permanent removal of the traditional dredging window of December 1 – April 15. Wilmington Harbor is part of the lower Cape Fear River, critical habitat for the Atlantic sturgeon.

“The Wilmington District completed an Environmental Assessment and Finding of No Significant Impact, in accordance with the National Environmental Policy Act, that addressed impacts of removing the hopper dredging window,” she said. “As a result of coordination with federal and state environmental agencies, the District is required to perform water quality sampling before, during and after hopper dredging for the next three years to ensure there is no danger posed by hopper dredging to the sturgeon.”

Keith Lockwood, chief of Norfolk District’s Water Resources Division, said that Balazik is now looking at the spawning and migration patterns of Atlantic sturgeon in the James River.

“He is trying to find spawning females in the upper portion near Richmond and looking at juveniles and their patterns in the middle and lower James River to see what effects these patterns could mean to navigation projects and dredging,” Lockwood said.

Balazik describes how, after years of working with the Norfolk District to monitor the sturgeon around hydraulic cutterhead dredges on the James River, he hasn’t found signs of avoidance from the sturgeon.

“They all swam past the dredges — none have turned around — they continued upstream,” he said. “One fish passed the dredge 13 times.”

The ERDC research ecologist made a discovery when he tried to collect data for the Norfolk District project.

“No one knew there was a fall spawning season — most species have a spring run and that’s it,” Balazik said. “We had to test, but there were restrictions already in place for the spring run. Once we learned that there was a fall run, and there were no dredging restrictions at that time, the pieces fell right in place — the weather conditions, the water, we got the telemetry.”

“This project has shown that dredging had no noticeable effect on migrating fish,” Balazik said. “This is the total opposite of what everyone expected to happen.”

Balazik’s discovery could have a big impact on both districts.

“This research could eventually result in relaxation or reduction in time-of-year restrictions for Norfolk District,” Lockwood said. “Sturgeon is a keystone species; if it’s conclusively shown that dredging is not affecting migration and spawning at any time, we will request that the regulatory agencies relax the restrictions.”

For the next three years, the Wilmington District has the flexibility to dredge the Wilmington and Morehead City Harbors without the constraints of windows.

“With the hopper dredge shortage we are facing right now, the ability to dredge at any time of year will help guarantee that entry to the ports is maintained at project depth as much as possible,” Hughes said.

“If sampling shows minimal and temporary changes to water quality, we may have the ability to dredge without seasonal restrictions permanently,” Hughes concluded.