Engineer Research and Development Center News Releases

Environmental DNA Metabarcoding Elucidates Freshwater Mussel Diversity and Occupancy to Facilitate Improved Management and Conservation

Press Operations — Fri, 05 Jun 2026 15:35:00 GMT

Abstract: Freshwater mussels are considered among the most at-risk taxa in the world. As such, comprehensive monitoring assessments of what abiotic and biotic factors influence mussel occupancy will be vital for guiding effective conservation. Here, we analysed vertebrate and mussel environmental DNA metabarcoding data to explore the influence of biotic and abiotic factors on freshwater mussel populations. This study utilised water samples and tactile survey data collected from streams throughout Fort Johnson, Louisiana. Methods: We first evaluated the effectiveness of eDNA metabarcoding for characterising freshwater communities based on previous conventional tactile surveys. Next, we used eDNA metabarcoding analysis for freshwater mussels and vertebrate species alongside GIS-derived satellite remote sensing data to assess how various biotic and abiotic variables impact freshwater mussel eDNA occupancy. Our eDNA metabarcoding survey largely agreed with both historical and contemporary surveys on Fort Johnson, while uniquely detecting Louisiana pigtoe, a proposed threatened species under the US Endangered Species Act. We also found that eDNA detections and occupancy had strong seasonal variation, with increased read abundance and diversity in the spring. Vertebrate, fish, and predator diversity were strongly predictive of mussel occupancy, supporting the concept of land managers focusing on the entire ecosystem for mussel conservation. Lastly, we found that percent forest cover and drainage basin size influenced mussel eDNA occupancy, informing habitat associations for mussel species of interest. Our results demonstrate that combining eDNA metabarcoding of target and non- target species with occupancy modelling can provide insights into the ecology of freshwater mussels and is a useful tool to improve their conservation and management.

Operational Analysis of Composting for Military Installation Resilience

Press Operations — Mon, 01 Jun 2026 19:57:00 GMT

Abstract: On military installations, food waste is the heaviest portion of solid waste. At a single installation, food waste and its management can contribute up to $1.5 million lost annually. Additionally, Army installations pay over $100 million annually in disposal fees. Army policy calls for source reduction and composting as preferred methods of waste management over landfilling. As of 2025, 11 states and Washing-ton, DC, have laws that restrict food waste from being landfilled, with some laws more stringent than others. Composting is one way to align with both Army policy and local laws. Several installations have on-post composting operations, and others send food waste to nearby commercial compost facilities, where those are available. In FY 2024, 33 installations reported food recycling, which includes composting, anaerobic digestion, and other food-waste diversion. If composting on-post, a suitable location, equipment, and labor are needed. Multiple methods of composting for an installation must be considered. But composting can be worthwhile and may be more economical than landfilling. When installations are deciding how to manage food waste, they should consider their resources, organic waste generation tonnage, labor availability, and potential for cost savings. Depending on their location, on-post and off-post commercial options may be possible.

Robust Error State Sage-Husa Adaptive Kalman Filter for UWB Localization

Press Operations — Thu, 07 May 2026 17:07:00 GMT

Abstract: Given the sensors’ path and interference mitigation capabilities, ultra-wideband (UWB)-based positioning systems have demonstrated high accuracy and reliability. This work aims to improve the Sage-Husa fuzzy adaptive filter (SHFAF) proposed in previous works by modifying the motion model to a 3-D ground-based differential drive robot using IMU and wheel encoder kinematic fused control inputs. In addition to the changed motion model kinematics, this article improved the positive definite constraint on P and R during dynamic estimations, thus making the filter more robust to outliers. An improvement to the computation and derivation of the fuzzy logic system for the SHFAF based on the adaptive neuro-fuzzy inference system (ANFIS) structure was developed, and training the fuzzy system using gradient descent was applied to improve the system’s accuracy. Experimental validation was conducted using real-world data from a Clearpath Jackal robot equipped with Qorvo UWB sensors and static nodes. Regarding localization accuracy, the proposed velocity-based SHFAF (VelSHFAF) system outperformed the previous SHFAF implementation by approximately 30%–25% across two test courses, demonstrating its enhanced performance and reliability.

Surface Oxide Removal in Preparation for Controlled Liquid Metal Embrittlement

Press Operations — Thu, 07 May 2026 17:05:00 GMT

Abstract: During liquid metal embrittlement a liquid metal inﬁltrates grain boundaries of a compatible solid metal, interrupting the inter-grain bonds and weakening the metal. Ongoing research has proposed that this effect may be used to perform additive/subtractive hybrid machining to fabricate replacement components, using relatively simple equipment and low material and instrument costs. The gallium/aluminum pairing is of particular interest due to the usage of aluminum in a wide variety of structural and aerospace applications coupled with gallium’s nontoxicity and melting point just above room temperature, which facilitates storage and transport. To activate aluminum to gallium inﬁltration, the surface oxide formed on aluminum in atmosphere must ﬁrst be removed simultaneously with a signiﬁcant amount of bulk metal to promote ﬂow control of the liquid metal. Three targeted techniques for oxide removal were tested and compared, speciﬁcally mechanical abrasion, chemical etching, and laser ablation. Mechanical abrasion is simple to implement but lower precision. Chemical etching requires signiﬁcant prep work and cleanup but could operate on entire sheets of substrate simultaneously with proper masking. Although laser ablation requires the most complex instrumentation, it requires minimal prep work and provides the greatest precision, making it ideal for the manufacturing application under development here.

Self Excited Hoisting Chain Tension Measurements for Dam Spillway Gates and Identification of Uneven Hoisting

Press Operations — Thu, 07 May 2026 17:01:00 GMT

Abstract: Tainter gates are critical components of inland navigation systems, as they regulate the flow of water through dams, enabling a navigable depth of waterway. A critical issue with Tainter gates arises when the gates are raised or lowered in a skewed, uneven fashion, which can cause redistribution of stresses and exacerbate fatigue damage. This uneven hoisting of the gate manifests itself as unequal tension in the chains that raise the gate. An opportunity to indirectly measure the tension in hoisting chains arose during field testing of a Tainter gate, where accelerometers were placed on easily accessible locations on the Tainter gate with the goal to perform a modal analysis of the gate. During operation, the hoisting chains of the tested gate would audibly pop, which was clearly identifiable in acceleration records and expected to be the response of the chains themselves, rather than the modal vibrations of the Tainter gate. To support the notion that the recorded vibrations represent the response of the chains, this paper explores the dynamics of the chains to develop the relationship between chain frequency and tension. The developed relationship is validated in a laboratory experiment of a chain cut from a Tainter gate where the natural frequency of the chain is measured for varying tension in the chain. The results of the study show that this approach can be used as a quick and inexpensive method to monitor for uneven hoisting on Tainter gates from easily accessible locations on the gate and with inexpensive sensors.

Hierarchical Rule-Base Reduction-Based ANFIS with Online Optimization Through DDPG

Press Operations — Tue, 05 May 2026 19:04:00 GMT

Abstract: This article presents a comprehensive approach to designing and optimizing a hierarchical rule-base reduction-based adaptive-network-based fuzzy inference system (ANFIS) for symmetric linguistic variables. Speciﬁcally, the linguistic connected membership functions that underlie the ANFIS are deﬁned, focusing on symmetrical inputs/outputs and jointly optimized trapezoid membership functions to reduce the number of training parameters. Further optimizations for the ANFIS were derived based on design assumptions, including training the membership functions on closed or single-sided domains. The optimal output membership weights based on mean square error optimization were also symbolically obtained. The online training of the ANFIS’s input/output membership functions was performed using the deep deterministic policy gradient (DDPG) algorithm. A simulated skid-steered vehicle was used to validate the approach and performed waypoint-to-waypoint path following. Experimental results using the Clearpath Jackal demonstrated that the ANFIS model converged quickly, typically within 6 to 10 episodes of training, from an initial mean absolute error (MAE) and root mean squared error (RMSE) of 0.88 and 1.02 m, respectively, to a ﬁnal MAE and RMSE of 0.087 and 0.10 m. The results highlight the effectiveness of the ANFIS approach for vehicular robotics applications and suggest promising avenues for future research and development.

Characterizing Lithium-Ion Battery Health and Mitigating Transportation and Recycling Hazards

Press Operations — Mon, 04 May 2026 19:43:00 GMT

Abstract: With the growing trend toward electric vehicle (EV) use, the demand for safe, efficient, and cost-effective energy storage grows increasingly crucial. The ability to effectively characterize battery health, transport and dispose of batteries safely, and mitigate the by-products of battery recycling are all important to reduce the risks of lithium-ion battery (LIB) usage throughout the battery’s life cycle. The transportation and disposal of LIBs present critical challenges and require stringent safety measures to mitigate risks effectively. Additionally, many recycling methods are less cost-effective or more environmentally harmful than mining new materials. This report describes the findings of a collaborative project between the University of Illinois Urbana-Champaign and US Army Engineer Research and Development Center, Construction Engineering Research Laboratory, to address these concerns and contribute to safer and more environmentally friendly transportation, recycling, and disposal of LIBs. The most common battery recycling techniques are investigated—pyrometallurgy, hydrometallurgy, and direct recycling—along with the environmental impact of these methods. The overall potential environmental impacts of LIB usage can be greatly improved through proper battery disposal. Addressing hazards at the battery level by enhancing the stability and cooling of batteries can simplify battery transportation and improve safety.

Installation Access Control Technology at Redstone Arsenal: Biometric-Enabled Technology for Installation Entry

Press Operations — Mon, 04 May 2026 19:39:00 GMT

Abstract: A pair of biometric capabilities useful for access control were demonstrated at Redstone Arsenal to support installation modernization and the integration of smart infrastructure. This project addresses gap requirements outlined in the March 2020 report to Congress by the Assis-tant Secretary of the Army for Installations, Energy, and Environment (ASA IE&E), Army Report on Creating an Army Installations Test and Demonstration Program Using Commercial Technologies. The demonstration tracked the number of transactions completed at an access control point (ACP) lane using a facial recognition system and at a secure facility using a touchless fingerprint reader and facial recognition kiosk. The operational duration of the systems showed their robustness. Multiple cameras in the express lane system accurately identified vehicle occupants while minimizing traffic backups. The touchless fingerprint system installed at the secure facility was easy to use, and users preferred it, leading to it quickly surpassing the existing method.

Hierarchical Rule-Base Reduction Fuzzy Control for Path Tracking Variable Linear Speed Differential Steer Vehicles

Press Operations — Thu, 23 Apr 2026 20:12:00 GMT

Abstract: A novel waypoint navigation controller for a skid-steer vehicle is presented, where the controller is a multiple input-multiple output nonlinear angular velocity and linear speed controller. Hierarchical rule-base reduction was used in deﬁning the controller. This entailed selecting inputs/outputs, determining the most globally inﬂuential inputs, generating a hierarchy relating inputs, selecting only the rules corresponding to the hierarchy, and, in effect, designing a symmetric rule-base. This dramatically reduced the rule-base size, by 97.7%, while maintaining global operating environment coverage. The stability analysis proved the asymptotic stability of the closed-loop controller-vehicle system. In addition, test courses were used to examine the effects of steering disturbance, phase lag, and overshoot as expressed in root mean square error (RMSE) and max error (ME). Outdoor experimental results for the controller’s performance were contrasted with a benchmark waypoint navigation controller, pure pursuit, and a simpler implementation that only output linear speed. The controller was found to outperform the pure pursuit and simpler implementation experimentally by 72% and 50% in RMSE, 71% and 40% in ME, validating the controllers viability.

A Simple Room-Temperature Refurbishment Method for Sulfated Lead-Acid Batteries Using Ammonium Acetate Treatment

Press Operations — Mon, 20 Apr 2026 18:50:00 GMT

Abstract: Current recycling paradigms of lead-acid batteries (LABs) involve the use of toxic, polluting, and energy- demanding processes. Here we report a novel strategy to refurbish LABs which failed due to the formation of hard sulfation on the anodes. We used ammonium acetate (NH4Ac) to selectively dissolve the water-insoluble lead sulfate (PbSO4) crystals which cause the hard sulfation from commercial LAB anodes and electrodeposit metallic lead on a new surface. The remarkable removal of hard sulfation was characterized by a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX). The treatment replenished a fresh LAB anode surface, recovering the capacity from ~0 % to 99 %. The dissolved Pb2+ was retrieved with an efﬁciency of >99.9 % through electrodeposition, completing a refurbishing process that minimizes the release of heavy metals into the environment. We demonstrated a proof-of-concept refurbishing of a full commercial LAB, which recovered 35 % of its capacity. With a noteworthy capacity renewal and minimal release of hazardous materials, NH4Ac refurbishing promises to be an environment-friendly and economic alternative recycling paradigm for the LAB industry.

A Synthesis of Freshwater Forested Wetland Soil Organic Carbon Storage

Press Operations — Tue, 14 Apr 2026 12:58:00 GMT

Abstract: Freshwater forested wetlands account for ~76% of the total global wetland extent. However, freshwater forested wetlands are difficult to distinguish from upland forest due to canopy coverage, the abundance of wetland-nonwetland mosaics, seasonal hydropatterns, and fewer readily observable connections to large surface water bodies relative to marshes and other emergent habitats. Therefore, freshwater forested wetland ecosystems are often misclassified as upland forests in carbon accounting models, underestimating soil organic carbon storage. This study highlights freshwater forested wetland SOC accounting challenges and presents SOC densities/stocks from a global literature synthesis across different freshwater forested wetland types. We reviewed 374 forested wetland articles, compiling and calculating carbon densities by depth from 90 freshwater forested wetland studies to construct a database of 334 study sites including nine countries. The median SOC stock was 91.2 ± 46.4 Mg C ha−1 and 235.3 ± 125.6 Mg C ha−1 in the top 30 cm and 100 cm of soil, respectively. The tidal freshwater forested wetland had highest SOC stock in the upper 100 cm soil profile followed by rainforest, non-tidal swamps, and floodplain forested wetlands. Within the conterminous United States forest type groups, the Tsuga/Picea group had the highest median SOC stocks in the top 100 cm of soil followed by Quercus/Pinus and Quercus/Liquidambar/Taxodium groups, likely driven by variability in litter degradability, wetland hydroperiod, geomorphic positions, and regional climatic factors. This literature synthesis highlights SOC accounting in freshwater forested wetland carbon pools when estimating carbon stocks and fluxes. Results can be used to improve carbon modeling outcomes, as well as inform regional, national, and global management of wetland carbon resources.

Vertebrates in Trade that Pose High Invasion Risk to the United States

Press Operations — Thu, 09 Apr 2026 20:23:00 GMT

Abstract: The United States imports thousands of live vertebrate species annually as part of legal trade. Escapes and releases from captivity are major pathways of invasion, however, the risk posed by the thousands of imported vertebrate species has not been systematically assessed. We conducted a horizon scan that used a data-driven climate match to ﬁlter a list of nearly 15,000 taxa drawn from across the globe of imported ﬁsh, amphibians, reptiles, birds, and mammals for rapid assessment by taxonomic experts. Experts evaluated 840 species and identiﬁed 32 as having the highest risk for establishment, spread, and negative impacts. Of those high-risk species, the majority have the capacity to disrupt ecosystem processes via their role as top predators or the unique ecological niches that they occupy, while several of the snake species pose a threat to human health. High-risk species were often scored with high conﬁdence while in contrast, low scores were attributed to a combination of ecological redundancy, low propagule pressure, or low climate match while low conﬁdence arose from a lack of information in the literature. Our study therefore highlights legally imported species likely to cause the greatest harm with the recognition that many other species could also become invasive in the United States. The ranked list of vertebrate threats can be used to prioritize watchlists and inform the development of targeted regulations for importation can be applied to regions to provide a rapid, preliminary screening for large pools of potential invaders.

Phase-pure Formamidinium Lead Iodide Perovskite Films Deposited via Flow-Limited Field-Injection Electrostatic Spraying

Press Operations — Wed, 08 Apr 2026 17:16:00 GMT

Abstract: Phase-pure perovskite formamidinium lead iodide (FPI) films were deposited using flow-limited field-injection electrostatic spraying at a deposition temperature of 120 ○C without employing stabilizing additives while retaining large-area scalability. The structures of the films were analyzed using the Rietveld refinement of x-ray diffraction measurements, enabling achievement of phase purity under optimized charging voltage and deposition temperature. The effect of precursor molar ratio on the phase of FPI was investigated by Fourier transform infrared spectroscopy, revealing the crucial role of the FAPbI3 ⋅ DMSO adduct formed in solution for achieving phase purity. Optical properties and photoactivity were assessed by absorption spectroscopy and time-resolved photoluminescence, demonstrating viability for application to solar cells.

The Use of Nitrocellulose Production Waste for Energy Generation

Press Operations — Tue, 03 Mar 2026 21:18:00 GMT

Abstract: The US Army Engineer Research and Development Center investigated the use of nitrocellulose (NC) fines, an ammunition waste, for energy generation. NC is a natural high polymer obtained from treating cotton or wool with nitric and sulfuric acid. It is widely used in the industry, with military applications being the largest use currently. Since military applications range from bullet propellants to missiles for tube munitions, large quantities must be produced to meet the demand. However, large NC production batches result in large quantities of NC fines waste, generated in the form of insoluble fibers in suspension in wastewater after manufacturing. Hence, a method to reuse this generated waste and convert it into energy was tested. This study evaluated the potential of creating energy from NC waste through hydrothermal liquefaction and gasification of NC, yielding methane (CH4) as the final product. Results demonstrated that the CH4 concentrations increased as the temperature, reaction time, and catalyst addition were increased, yielding a maximum concentration of 2,000 ppm (6,400 peak area of the chromatograph). The homogenous catalyst performed better than the heterogenous catalyst, since it increased the CH4 yield up to 6 times the concentration obtained with no catalyst added.

Infection Risk Assessment for Socially Structured Population Using Stochastic Microexposure Model

Press Operations — Wed, 18 Feb 2026 21:53:00 GMT

Abstract: Predicting infection outbreak dynamics within local microenvironments is a challenging task. Some methods assume smaller population pools and often lack the statistical power of inferences. Others are designed for larger population pools and cannot be downscaled to accommodate the details of microenvironments. Practicable infection risk assessment models should account for population size, geometry and occupancy of public places, behavioral and professional patterns of daily routines, and societal structure. This study is based on the stochastic microexposure model, which has been generalized to describe clustered populations. The methodology is demonstrated for a community of several thousand students on campus. The results indicate the social structure has the ﬁrst order effect on the spread of the infection. Depending on the number, size, and degree of inner- and outer-cluster connections, the outbreak exhibits distinct durations, power, and multiple peaks of infection. Moreover, the contribution of different microenvironments to infection risk evolves during the course of the outbreak. Social structure plays a major role in infection spread and should be accounted for in risk prediction tools. The stochastic microexposure model accounts for the social structure of a population at multiple scales and can predict the dynamic contributions of different microenvironments to infection spread risks.

Public Risk Perceptions of Advanced Water Purification in an Arid Urban Region of the U.S. Southwest: A Mixed Methods Study

Press Operations — Tue, 03 Feb 2026 19:33:00 GMT

Abstract: As water utilities implement potable reuse technology, there is a need to understand how to increase public acceptance and trust in public water supplies. The study objective was to use surveys and interviews in a large metropolitan area in Arizona to characterize tap water and advanced puriﬁed water acceptability, and factors contributing to (un)acceptability. Participants were recruited through a water utility email listserv for participation in an online REDCap survey and/or 1-hr Zoom interview. Surveys and interviews inquired about perceptions of tap water safety, familiarity with water reuse terms, acceptability of direct potable reuse (called “advanced water puriﬁcation” in our study for consistency with state messaging), and rationales related to acceptance. Four hundred seventy-nine individuals participated in the survey, and twenty-two individuals participated in the interviews, with roughly comparable demographics for our city of interest but with slightly higher levels of household income and education. Only 36 % of survey respondents use their tap water for drinking water supplies, but (42 %) would be open to drinking advanced puriﬁed water. Semi-structured interviews were conducted in 2024 on risk-based thinking to evaluate how advanced puriﬁed water may compare to current drinking water safety and analyzed with inductive thematic analysis. Survey and interview participants wanted more reassurances (e.g., third party testing and opportunities for hands-on testing). Water utilities should prioritize transparent communication strategies, including sharing detailed third-party testing data and direct community engagement initiatives, to enhance public acceptance. Utilities can build trust through clear comparisons between advanced puriﬁed water and current tap water quality.

Composite Materials for Sector Gates and Vertical Lift Gates: Report of FY22–FY24 Project Outcomes

Press Operations — Thu, 29 Jan 2026 13:57:00 GMT

Abstract: This project supported a Statement of Need (SON) submitted to the Navigation Research Area Review Group: SON 2021-1505 by David Weston, Business Line Manager for Inland Navigation (INAV) and Flood Risk Management (FRM) at Jacksonville District. The goal of this study was to provide design guidance, criteria, and performance standards for professionals to use in the design, retrofit, maintenance, and repair of Canaveral sector gates and W. P. Franklin vertical lift gates using structural grade fiber-reinforced polymer (FRP) composites. The results also contribute to guidance documentation used for Hydraulic Composite Structures at other INAV structures. Our work focused on four main subject areas: direct field support, workforce education, structural connection design and modal analysis, and inspection guidance. As this research project progressed through three FYs in coordination with stakeholders across the US Army Corps of Engineers (USACE) and industry, the Inland Navigation Design Center (INDC) and the Jacksonville District gained competency in hydraulic composite structures design techniques, which enabled their successful award of a contract for composite bulkheads at Port Mayaca and vertical lift gates at W. P. Franklin.

Knowledge Gaps and Education Opportunities on Direct Potable Reuse: Interviews with Customers of a Large, Southwestern United States Water Utility

Press Operations — Thu, 22 Jan 2026 17:03:00 GMT

Abstract: Water scarcity is a global public health threat that has increased urgency in implementing new sustainable practices to protect water supplies, such as the use of direct potable reuse, or “advanced water puriﬁcation (AWP)". The study objective was to use interviews to characterize knowledge gaps and community outreach strategies to increase successful AWP implementation in an arid city in the southwestern United States. Through partnership with a water utility in an urbanized area of Arizona, 6000 individuals were emailed for invitation to participate in interviews. Interviews were conducted over Zoom and transcribed verbatim. Transcripts underwent inductive thematic analysis. Twenty-two individuals participated in interviews, and saturation of themes was reached. Five main themes emerged: 1) Conﬂation of ﬁlters with all treatment and the inﬂuence of residential technologies, 2) individual-level control over decisions to use advanced puriﬁed water, 3) desire for regulation, testing, and transparency about testing results, 4) concerns about speciﬁc chemicals, 5) educational resources to strengthen community engagement. Participants expressed lack of knowledge about how water is delivered to their residences by expressing the desire for opting in or out of system-wide treatment approaches.

Fiscal Year 24 Sustainable Design and Development Support Order: Identifying Building Electrification and Decarbonization Opportunities for Army Leadership in Energy and Environmental Design (LEED) Projects

Press Operations — Wed, 14 Jan 2026 18:35:00 GMT

Abstract: In fiscal year 2024, the Army advanced its strategic goals for resilient and sustainable building design, certifying 12 new Leadership in Energy and Environmental Design (LEED) projects and reaching a total of 899 LEED-certified projects since 2006. Key findings of this report reflect the Army’s alignment with updated LEED prerequisites, including increased energy performance standards and new green-house gas emissions metrics. The ongoing challenges in decarbonization and electrification, including increased construction costs and maintenance uncertainties, underscore the need for early integrative planning and improved data collection. The report highlights the best practices and technology solutions that are critical for reducing carbon footprints and enhancing operational resilience for the purpose of closing implementation gaps in complying with new policy, such as the Department of the Army Policy Guidance on Resilient Buildings released 27 March 2024 and the 29 March 2023 DoD memorandum on Electrification of Standard Building Operations. The report also emphasizes the importance of early LEED documentation to improve certification outcomes. With the upcoming LEED v5 release and evolving Army policies, this year’s progress sets a strong foundation for further implementation of electrification and sustainability efforts in alignment with Army resiliency goals.

Evaluation of Seven Bridges at Fort Hunter Liggett, California, for Eligibility to the National Register of Historic Places

Press Operations — Wed, 07 Jan 2026 20:29:00 GMT

Abstract: The US Congress codified the National Historic Preservation Act of 1966 (NHPA), the nation’s most effective cultural resources legislation to date, mostly through establishing the National Register of Historic Places (NRHP). The NHPA requires federal agencies to address their cultural re-sources, which are defined as any prehistoric or historic district, site, building, structure, or object. Section 110 of the NHPA requires federal agencies to inventory and evaluate their cultural resources, and Section 106 requires them to determine the effect of federal undertakings on those potentially eligible for the NRHP. Fort Hunter Liggett is in central California, within Monterey County. It was first established as the Hunter Liggett Military Reservation in 1941. The post was renamed Fort Hunter Liggett in 1975. This report provides a determination of eligibility for the NRHP for seven properties (Bridges 749, 750, 753, 760, 767, 779, and 781) constructed between 1965 and 2010 and recommends that none are eligible under the NRHP and the California Register of Historic Resources (CRHR) criteria.