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Corps to assess levee project’s impact on the environment

ERDC PAO
Published Jan. 11, 2019
Corps to assess levee project’s impact on the environment

Jay Price, U.S. Army Engineer Research and Development Center-Environmental Laboratory, uses a 10-factor prism to estimate tree basal area.

Corps to assess levee project’s impact on the environment

Wetland conditions at the project work locations; water marks on trees are the result of frequent inundation when the Mississippi River reaches flood stage.

VICKSBURG, Miss. (Nov. 27, 2018)--Dr. Jacob Berkowitz, Dr. Rich Fischer and Dr. Jack Killgore, along with other researchers from the U.S. Army Engineer Research and Development Center’s Environmental Laboratory, will be contributing research information to a Supplemental Environmental Impact Statement for a Mississippi River Mainline Levee project. The SEIS will be provided to the Mississippi Valley Division and three district offices responsible for managing the project.

“It’s a requirement, under the National Environmental Policy Act, for agencies to complete an Environmental Impact Statement prior to implementing a large-scale project,” Berkowitz said. “The purpose of the EIS is to see what natural resources may be affected by a project, and what measures can be taken to offset those affected resources.”

The USACE Mississippi Valley Division and the Vicksburg, Memphis and New Orleans Districts are implementing a program to complete and revamp over 130 segments of a large levee system along a section of the Mississippi River extending from Cape Girardeau, Missouri, to Head of Passes, Louisiana. The levee system is one component of a structural complex built after the Great Mississippi Flood of 1927 — as part of the Mississippi River and Tributaries project — to control flooding along the Mississippi River; the maintenance and repairs will address overtopping, seepage and other issues.

“This effort is to bring the Mississippi River Levee system, which is about 80% complete, to its congressionally authorized design grade and to maintain and reinforce what already exists,” said Daniel Sumerall, Project Manager, Vicksburg District. “Although the main work of the project has been addressed, we are still doing some fine-tuning.”

The first EIS connected to the project was completed in 1976 to meet NEPA requirements. The first SEIS was completed in 1998, and Killgore took part in that SEIS effort; this will be the second SEIS.

Berkowitz will evaluate wetlands impacted by the project using models and a system called the Hydrogeomorphic Method, which was developed in the Environmental Laboratory.

“We have come a long way since the 1990s with assessing how these types of projects affect natural resources such as wetlands, fisheries and aquatic and terrestrial environments — including birds, bats, mink and other species of concern. In the 1990s, ecological modeling was still somewhat new, and computer technology, aerial photography, the models and the research underpinning the models have all significantly advanced so that the models are a lot more accurate.”

Berkowitz said that one way the Corps mitigates for impacts to wetlands is restoration. “We typically figure out how many acres of wetlands are impacted by the levees, and then we buy land and restore it to wetland habitat. We may take areas of farmland that have a tendency to be saturated anyway, and restore those sections, since they were likely originally wetland before they were converted and utilized for agriculture.”

Fischer will assess the terrestrial species, using a model called Habitat Evaluation Procedures to evaluate how the barred owl, fox squirrel, pileated woodpecker, and other species will be impacted by the construction. “Building on the SEIS that was conducted in 1998, we will evaluate a wider range of species than those examined in that period,” Fischer said. “And we have a wide range of migratory birds that are protected under the Migratory Bird Treaty Act — we need to evaluate how they will be impacted.”

Killgore will address the aquatic dimension, which involves the study of borrow pits. “When we build or augment levees, we typically use material from the river floodplain.” Killgore said. “These areas of borrowed material are called borrow pits.”

“We want to maximize the value of the borrow pits to the environment. The borrow pits can take many shapes and sizes — there are deep ones, shallow ones; we may add an island, if it’s beneficial; we may make the shoreline sinuous to add structural complexity to the pit.”

“In the 1990s, we looked at borrow pits created in the 1980s. This time, we’ll address eight of the same borrow pits, so we’ll be completing a 30-year evaluation of some of them. We’ll be very interested to document the changes and the similarities between the two periods, including impacts of Asian Carp on the native fish community.”

“We’ll look at how frequently the borrow pits are connected to the river — the connectivity dictates the types of fish species that find their way into the borrow pits. The borrow pit shape determines how many aquatic species, such as the pirate perch and the taillight shiner, survive. We’ll do some habitat mapping and trap and collect samples, and we’ll develop correlations between borrow pit environmental factors and fish survival.”

The SEIS will be published in 2020.