Five years of post-construction monitoring data (Fuller 2018) suggest adaptive management action is needed at The Nature Conservancy’s (TNC) 4,122 acre Port Susan Bay Preserve, located at the mouth of the Stillaguamish River. The overall resiliency of the estuary is not rebounding as expected since the 2012 dike and levee removal, which resulted 150 new acres of estuary habitat. Therefore, TNC seeks to reverse this trend and foster native marsh development by increasing freshwater flow and tidal connectivity to the 2012 restoration site. Connectivity enhancement through channel creation, berm removal, and dike modification will enhance drainage and provide increased access for salmon. Increased freshwater residence time in the restoration area?will directly address the salinity stress currently affecting the marsh habitat; critical for juvenile salmon, shorebirds, and other estuarine-dependent animals.At this time, TNC is requesting ESRP funding for final design for estuary habitat enhancement. We propose to obtain updated LiDAR base maps for use in two models (an allometric channel model and 2D hydrodynamic model) and conduct a geotechnical analysis. These tasks would inform an alternatives analysis for restoration action, to be advanced to 100% design and permitting.