The Agat Emergency Shoreline Protection Study was a federal study to evaluate and identify emergency shoreline protection measures at the Agat Mayor’s Complex in Hågat, Guam (formerly known as Agat).
The study was authorized under Section 14 of the Flood Control Act of 1946 (P.L. 79-525), as amended (33 U.S.C. 701r), for emergency shoreline protection under the Continuing Authorities Program. This feasibility study began in February 2023 upon execution of a Feasibility Cost Share Agreement and concluded with final approvals in August 2026, followed by final signatures completing the feasibility phase in September 2026.
The non-Federal sponsor for the study was the Government of Guam, represented by the Guam Bureau of Statistics and Plans and the Guam Department of Public Works. The study costs were cost shared between the U.S. Army Corps of Engineers (USACE) and the non-Federal sponsor. Upon conclusion of this feasibility phase, the project will move to the Design & Implementation phase once funding is acquired and a Project Partnership Agreement is executed.
The Agat Mayor’s Complex is located along Route 2 fronting Agat Bay on the west central coast of Guam. The public facility serves as the municipal government headquarters of Agat and includes the Mayor’s office, community center, learning center, computer lab, emergency shelter, evacuation facility, post office, and Sagan Bisita community gathering space. The complex provides critical municipal, community, and emergency services to approximately 4,917 residents of Agat and serves as a primary shelter and recovery hub during extreme weather events.
An existing concrete rubble masonry seawall, constructed in the early 2000s to protect the complex, is on the verge of collapse due to chronic shoreline erosion and undermining. The coastline is subject to frequent storm wave attack and was severely impacted by Typhoon Yutu in 2018 and Typhoon Mawar in 2023, leaving the community center and adjacent structures highly vulnerable to wave overtopping and storm surge. Bounded landward by Route 2, the only major roadway along the western shore of southern Guam, the complex has no room to retreat. Without immediate protection, the seawall will fail, resulting in severe structural damage and the complete loss of vital emergency response capabilities for the southern villages.
Figure 1. The study area runs along a 320-foot stretch of beach, which runs parallel to Agat Mayor Compound. Image courtesy of USACE, Honolulu District
Figures 2 and 3: Erosion and undermining of the existing seawall built to protect the facilities is visible in within the study area. Photos courtesy of The Bureau of Statistics and Plans, Government of Guam
In late 2024, USACE released the Draft Integrated Feasibility Report and Environmental Assessment (IFR/EA) for a 45-day public review and comment period. A hybrid public meeting was held on October 16, 2024, at the Agat Mayor's office and virtually to present the plan and solicit feedback from territory agencies and local residents. The study team incorporated public and agency input to refine the plans and finalize the IFR/EA, which was approved in August 2026 to conclude the feasibility phase.
The recommended plan presented in the final IFR/EA is Alternative 3: Open Cell Piling Seawall. This plan was selected as the least-cost environmentally acceptable alternative, fulfilling the federal justification requirement for Section 14 projects. It was also determined to be the Least Environmentally Damaging Practicable Alternative (LEDPA). The structure consists of a 320-foot-long vertical, vinyl open cell sheet pile seawall backfilled with reinforced concrete, anchored 5 feet into the underlying solid limestone shelf using 2-inch diameter pin piles, and secured to concrete deadman anchors with tieback rods every 8 feet.
The finished seawall will feature a uniform crest elevation of +6 feet above mean sea level, concrete stairs to maintain public beach access, and a 4-foot-wide splash apron to mitigate wave overtopping. This design meets the USACE criteria for expected design life and adaptability to relative sea level change. At federal fiscal year (FY) 2026 price levels, the total project first cost of the recommended plan is approximately $7.19 million, with initial construction scheduled for FY 2029.