Mobile Baykeeper Challenges the Ship Channel Expansion Study - Here Is Why You Should Too

Mobile Baykeeper Challenges the Ship Channel Expansion Study - Here Is Why You Should Too

Details of the proposed Mobile Ship Channel expansion are shown above. Image - United States Army Corps of Engineers

The Corps is studying plans to deepen and widen the Mobile Ship Channel. After reviewing the Corps’ draft study, the Supplemental Environmental Impact Statement (SEIS), we have some major concerns. Currently the study concludes “no impacts” will result from deepening and widening the Mobile Ship Channel.

After speaking with local experts, community members, and doing our own research - the study is inadequate and likely underestimates the impacts to our precious natural resources.

Below are our main concerns - we need you to take action and submit comments by 5pm, Monday Sept 17th. Copy and paste or write your own comments in the form below to make a difference today!

Our main comments on the study include:

Use more than one year as the base for modeling impact

The Corps used only one-year (2010) as the base for a number of studies including water quality. Results from the water quality study (i.e changes to salinity, oxygen levels etc.) were then used to find out how these changes will impact our aquatic life (wetlands, oysters, seagrasses). This limitation of data could cause the impact from the proposed project to be underestimated. The Corps must include at least three-years of data to show how droughts and severe weather impact results.

Include how pollution/invasives/etc. will enter Mobile Bay with a deeper channel

Seagrasses and mapping of potential impacts. Image- United States Army Corps of Engineers

The Corps must study how pathogens, harmful algal blooms (such as red tide), and oil spills will move through the Bay with a new channel dimension.

The Corps must evaluate the potential for non native or invasive species (for example lionfish) to increase as a result of changes in salinity and temperature.

Acknowledge past impacts

The Corps is required to acknowledge the previous study conducted in 1980 (and several Corps reports since then) to determine historic impacts. This is particularly important as impacts to the western shoreline of Mobile Bay and Dauphin Island are significant and cannot be ignored.

Evaluate indirect impacts

The Corps must understand how the proposed project, improvements and increased efficiency of the channel, will generate growth opportunities, bringing new development and expanding existing facility footprints, that could have indirect impacts to our natural resources.

Improve Ship wake analyses

We have concerns with the Vessel Generated Wave Energy study used to identify ship wake impacts. The following are problems we see with the current study:

 Port activity on the Mobile River.  Image - United States Army Corps of Engineers

Port activity on the Mobile River. Image - United States Army Corps of Engineers

  • Potential bias from field data collected only from N of Gaillard Island where vessel speeds are lower;

  • Information from only a limited number of ship sizes and weights;

  • Not including larger vessels like the Post Panamax Gen III anticipated to call at the port; and

  • An unvalidated assumption of fewer ships “With Project” than “Without Project”.

As a result, the study is underestimating ship wake impacts. The Corps must study the impact from ship wave energy on our aquatic life (oysters, seagrasses, etc.) and our shorelines.

Must acquire feedback from scientists in the oyster assessment

Oysters and natural oyster reef. Image - United States Army Corps of Engineers

  • The Corps’ study on how the project will impact oysters is incomplete.

  • The study fails to use and compare their model to an existing high quality model developed by local scientists.

  • The model showing how young oysters will move around after the channel changes (making sure they don’t get flushed out of the bay) only looked at one oyster reef. We strongly suggest the model be run from all reefs.

  • The Corps has not considered all the natural oyster reefs that exist in and around the bay. The Corps must use this data to ensure all sites are being analyzed.

The Corps needs to study how oyster drills (who eat oysters) will be impacted from the channel. Oyster drills like salty water and with higher salinity in the bay, they could increase and move into new areas, impacting oyster survival.

Dig deeper into wetland, seagrasses, fish, and species living on the bay floor

  • Because the Corps has limited their water quality studies to one year, impacts to natural habitats (wetlands, seagrasses, etc.) are likely underestimated.

  • The Corps identified some impacts to seagrasses but has not studied how these impacts will affect the species that rely on them like the West Indian Manatee and waterfowl.

  • Increases to salinity (as much as 3 ppt by Little Sand Island) is predicted by the study is a major concern. Salinity increases impact fish survival and habitat. The Corps must identify what fish live in the areas that will receive the highest increases to salinity.

  • The Corps sampled species that live on the bottom (crabs, shrimp, and many little organisms that are important food sources for fish). The sampling was limited to fall and spring and focused on only the upper portions of the bay. The Corps must seek datasets or use field verification to address these data gaps.

Find ways to lessen impacts to environmental justice communities and air quality

  • We are concerned with the study results showing an increase of truck traffic by 25% and a 2.5% increase in petroleum and hazardous materials to be transported through environmental justice communities. How will the Corps account for this impact?

Must acknowledge past impacts on air quality

The Corps’s air quality study used a baseline of 2011 but the Corps is required to consider past impacts from studies conducted in 1980.

Needs to gather community input & carefully select dredge material placement sites

  • More up to date surveys and verification with local scientists, state agencies, and community members to understand what is currently living in these areas to make sure dredged material does not end up in the wrong place.

  • The Corps should use the approximately 1.7 million cubic yards of “new work material” (what will be dredged to expand) from the Choctaw Pass Turning Basin that is made of clean sands for Beneficial Use.

  • The Corps must expand the Sand Island Beneficial Use Area (SIBUA) to address the low replenish rate issue where little material being dumped in the SIBUA is actually making it to Dauphin Island to replenish shorelines. If the site is expanded and the replenish rates are still low, the Corps will need to adjust until rates become maximized.

  • We suggest the Corps consider creating a Dredge Management Plan that includes all proposed projects in the Mobile Bay area.

Overall, the Corps’ “no impact” conclusion is very concerning

We are concerned with the Corps’ conclusion of “no impacts” from a large project proposed in a sensitive environment like Mobile Bay. We need your support in telling the Corps the study is inadequate and underestimating the true impact.

Take Action! Submit Your Comment Letter Using the Form Below

Send your comments now! The public comment period closes on Monday Sept. 17th.


Questions, comments, or concerns? Let us know! Contact Program & Grants Coordinator Laura Jackson at ljackson@mobilebaykeeper.org or call (251)-433-4229.


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