Evaluation of the Proposal for Widening and Deepening the Matagorda Ship Channel

There is a proposal for deepening and widening the Matagorda Ship Channel. However, there are concerns about specific environmental impacts to Matagorda Bay and Lavaca Bay such as: 1) Circulation and storm surge changes due to changing the bathymetry of Matagorda and Lavaca Bays due to deepening the channel and placement of dredge spoil parallel to the channel, which will funnel tidal movement along the axis of the bay and restrict mixing perpendicular to the channel. 2) Salinity changes due to the circulation changes and connecting with the puncturing of the groundwater lens beneath the bay. 3) Placement of dredge spoil could smother benthic habitats, such as oysters, seagrasses, or muddy bay bottoms and affect forage for desirable fish species. 4) Effects to primary producers or bottom dwelling organisms due to an increase in turbidity during the actual dredging. 5) Mobilization of mercury by the dredging because there are considerable amounts of mercury in sediments of the bay. 6) Plastic and microplastics interactions with sediments, turbidity, and other pollutants. The current study was undertaken to assess these possible concerns. The assessment has been done in two parts to identify potential physical and ecological effects. The assessments were based on a literature review of existing information. No sampling was conducted.