ML25233A138

Fws to NRC, Technical Assistance Letter

ML25233A138
Person / Time
Site:	05000614
Issue date:	08/14/2025
From:	Martin C US Dept of Interior, Fish & Wildlife Service
To:	Healy S Office of Nuclear Material Safety and Safeguards
References
2025-0115594
Download: ML25233A138 (1)

Text

In Reply Refer To:

2025-0115594 August 14, 2025 Shannon Healy Environmental Scientist Office of Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001

Dear Ms. Healy:

The U.S. Fish and Wildlife Service (Service) acknowledges the December 20, 2023, letter from Dow and X-Energy requesting technical assistance regarding an application to the U.S. Nuclear Regulatory Commission (NRC) for a license to construct and operate the proposed Long Mott Generating Station, a nuclear power station in Calhoun County, Texas. The Service received the Long Mott Generating Station Environmental Report on June 30, 2025, and met virtually with NRC on July 3, 2025, to discuss potential project impacts to threatened and endangered species.

The purpose of this letter is to provide technical assistance related to threatened and endangered species and other Service trust resources that could be impacted by the proposed project. The Services comments are provided in accordance with the Fish and Wildlife Coordination Act (16 U.S.C. 661-667), the Endangered Species Act of 1973 (ESA; 16 U.S.C. 1531 et seq.), the Migratory Bird Treaty Act (MBTA; 16 U.S.C. 703 et seq.) and the National Environmental Policy Act (42 U.S.C. 4321-4347).

According to the information received, the proposed Long Mott Generating Station would be constructed within an industrial zone on an approximately 1,548-acre site adjacent to the existing Union Carbide Corporation Seadrift Operations facility. The current land use of the site is primarily agriculture. Construction would include a nuclear power facility, stormwater basin, meteorological evaluation tower, transmission lines, pipelines, access roads, and parking lots.

The nuclear plant would consist of four Xe-100 reactor modules, which are high temperature gas-cooled reactors. The purpose of the Long Mott Generating Station is to provide both electricity and high-temperature steam to Dow's facility, for the production of chemical and plastic products. The proposed nuclear power plant is characterized as the first grid-scale advanced nuclear reactor for an industrial site in North America and would demonstrate the potential for reducing reliance on fossil fuels for energy.

Shannon Healy, Environmental Scientist 2

Comments The proposed project is within a subtropical, often semi-arid, region of Texas, with an average annual rainfall of about 40 inches and with limited sources of freshwater (Kleiner 2025). The Service recommends limiting water consumption needed for the facilitys operations and evaluating potential impacts to freshwater sources that are required to sustain ESA-listed species inhabiting the area, including freshwater mussel species and the whooping crane. The Service also recommends coordination and participation in the Guadalupe-Blanco River Authoritys Habitat Conservation Plan (see more information below in the freshwater mussel section).

The proposed project site is less than 25 miles from the Gulf of America and is therefore susceptible to potential damage caused by tropical storms and hurricanes. The Service recommends an analysis of potential impacts caused by flooding and hurricane-force winds that could cause infrastructure damage leading to spills of hazardous material, including radioactive waste and radioactive fuel, and preparing a fail-safe contingency plan for hurricane response.

The Service also recommends an analysis of potential effects of increased frequency and duration of drought (Nielsen-Gammon et al. 2020) and the projected continuation of sea level rise in this region (Virginia Institute of Marine Science 2023).

The proposed project is located near the Union Carbide plant, Seadrift Coke LP, and the Victoria Barge Canal. It is approximately 15 miles southwest of the Alcoa superfund site. Previous or current industrial activities have produced known contaminants in this area, some of which have spilled into the environment. These include wastewater treatment and the production of ethylene oxide, bauxite, alumina, aluminum products, mercury, polyaromatic hydrocarbons, and microplastics (Landry et al. 1997, Sager 2002, Bissett 2007, Tunnell et al. 2020).

Due to the abundance of state and federal trust resources within proximity to the proposed project site, and the environmental impacts that have already been sustained from the areas existing industries, the Service recommends that NRC fully evaluate all potential direct, indirect, and cumulative environmental impacts from the construction and operation of the Long Mott Generating Station. In addition to federally listed threatened and endangered species, impacts to state listed threatened and endangered species, State Species of Greatest Conservation Need, wetlands, and freshwater resources should be evaluated. The Service recommends that NRC consider preparing an Environmental Impact Statement to fully evaluate the cumulative effects throughout the proposed projects area of influence.

Migratory Birds Wetlands, woodlands, and coastal prairies provide nesting habitat for birds protected by the MBTA. In South Texas, agricultural fields also often support nesting birds, such as the dickcissel (Spiza americana) and eastern meadowlark (Sturnella magna). To avoid or minimize impacts to birds protected by the MBTA, the Service recommends avoiding vegetation clearing, material placement, or ground disturbances in the proposed project area during peak nesting season, between March 15 and September 15. If nesting season cannot be avoided, the Service recommends conducting bird surveys no more than five days prior to activities. Surveys should

Shannon Healy, Environmental Scientist 3

look for birds, nests, and eggs. If active nests are found, the Service recommends leaving a buffer of existing habitat at least 100 feet around nests until young have fledged or the nest is abandoned.

Because much of the proposed project will be located within agricultural land, we recommend awareness of the many species of MBTA-protected birds that over-winter in agricultural habitats in South Texas, such as the western burrowing owl (Athene cunicularia), mountain plover (Charadrius montanus), and savannah sparrow (Passerculus sandwichensis). The western burrowing owl is known to occur in the project area and is classified as a Bird of Conservation Concern on the Continental scale (https://www.fws.gov/migratorybirds/pdf/management/birds-of-conservation-concern-2021.pdf). Western burrowing owls use road culverts, small crevices, or mammal burrows as roost sites in open habitats such as pastures and plowed fields. Although winter roost sites are not protected, this small owl depends upon burrows for protection and survival against avian predators. For this reason, the Service recommends conducting burrowing owl surveys prior to work occurring between October and March and consider mitigation if western burrowing owls are found roosting in proposed project areas. For more information about western burrowing owl winter ecology, see https://www.loc.gov/item/2023693548 or contact the Service for best management practices.

Artificial lighting is increasing globally and is known to disrupt wildlife migration and circadian rhythms. Because the Texas coast provides habitat for federally protected species and is within the circum-Gulf migration route for many species of songbirds and raptors, the Service recommends implementing light pollution guidelines on all new structures and buildings. There are simple ways to minimize and manage lighting. If nighttime work is required, lighting should be down shielded, aimed only at the work zone, and turned off when not needed. Lighting should be the lowest intensity needed to illuminate the area of interest. For more information, please visit the International Dark-Sky website (https://www.darksky.org/our-work/lighting/lighting-for-citizens/lighting-basics/) and Bird City Texas (https://tpwd.texas.gov/wildlife/birding/bird-city-texas) for additional guidance.

Threatened and Endangered Species The Service recommends consultation under Section 7 of the ESA to ensure that NRC actions are not likely to jeopardize the continued existence of listed species or destroy or adversely modify designated critical habitat. As technical assistance, the Service is providing the following species-specific recommended conservation measures and best management practices to consider when consultation with the Service is initiated. Conservation measures represent actions, pledged in the project description, correspondence and/or meetings that will be implemented, to the extent practicable, to avoid and minimize the adverse effects of the proposed action and further the recovery of the species under review. However, even with the implementation of the conservation measures, there may still be adverse effects related to incidental take that may remain and require initiation of formal consultation. The inclusion of conservation measures into the project proposal would streamline any formal consultation that may still be required.

Shannon Healy, Environmental Scientist 4

Whooping Crane (Grus americana)

The endangered whooping crane winters along the Texas coast from November 1 through April

30. Whooping crane critical habitat is approximately 12 miles from the proposed project. If proposed actions cannot be conducted outside of the November 1 through April 30 wintering season, the following conservation measures are recommended:

Tall structures including buildings, construction equipment 15 feet high or higher, fences, and antennas in the area should be marked/flagged or laid down on the ground at night or when not in use to provide higher visibility and avoid or minimize potential whooping crane collisions.

Workers should be educated, with approved Service materials, to recognize whooping cranes, their habitat, and their federally endangered status.

A biological monitor with work-stop authority should be present from start to finish of the project in the event a whooping crane appears on the work site.

If a whooping crane does appear near the site and is within 1,000 feet of the construction area, work should cease until it has moved beyond that distance or left the area.

Fence construction designs should include fence markings and be <4 feet (~1.1 meters) in height to minimize collisions.

Report sightings of whooping cranes to the Texas Coastal and Central Plains Ecological Services Field Office in Corpus Christi at (361) 533-6765.

Eastern Black Rail (Laterallus jamaicensis jamaicensis)

The threatened eastern black rail (BLRA) may be present year-round in all Texas coastal counties. The species is most vulnerable during breeding, chick rearing, and the flightless molt period (March 1 through September 30). Where black rails may be present, avoid disturbance activities during the vulnerable period in BLRA habitat, e.g., dense overhead cover, moist soils that are occasionally dry and interspersed or adjacent to shallow water, depths up to 5 centimeters but typically less than 3 centimeters. If this timing restriction cannot be achieved, then the following measures are recommended.

Survey pre-project to assess BLRA presence or project proponents may assume presence within BLRA habitat. Survey recommendations will be given project by project; please coordinate with the Services Texas Coastal and Central Plains Ecological Services Field Office.

Limit project activity to daylight hours to the extent possible. If nighttime work is required, aim lighting at work zone and turn off when not needed, as possible. All permanent lighting should be pointed away from potential BLRA habitat, down shielded, and follow the International Dark-Sky Association (https://www.darksky.org/) guidance or Bird City Texas (https://tpwd.texas.gov/wildlife/birding/bird-city-texas) guidelines.

A biological monitor should ensure a sufficiently slow pace (5 miles per hour or less) of all equipment moving through potential habitat to allow birds to escape ahead of equipment. This secretive species will freeze or run to escape oncoming disturbance and is highly unlikely to fly.

Shannon Healy, Environmental Scientist 5

Do not remove all BLRA habitat in a day. Leave pockets of BLRA habitat (refugia) and/or have a biological monitor ensure dense herbaceous covered pathways are maintained into unaffected areas. The refugia remaining within the project area may be cleared after two days, as needed. Acceptable refugia size is approximately 10 feet by 20 feet. For small projects adjacent to wetlands, use linear clearing toward the remaining habitat.

The biological monitor will have authority to stop work immediately upon discovery of any BLRA (alive, injured, or dead). The Service should be contacted immediately at 361-533-6765.

Projects involving revegetation of disturbed areas should use native herbaceous plants mimicking the local site composition. Propagation of woody species should be avoided in BLRA habitat restoration areas.

The national research standard for BLRA call-response surveys can be found here:

Eastern Black Rail Call-Response Survey Protocol for Range-Wide Monitoring l FWS.gov. Surveys shall be conducted between April 1 and June 15 to verify the presence or absence of the species.

Survey results are valid through February of the following year. Any work that extends into the following breeding season will require an additional survey effort.

Should the survey results indicate that no rails are present, work may continue as normal.

If active nests are found, the Service recommends leaving a buffer of vegetation at least 100 feet around nests until young have fledged and the molting period has ended. The Service uses September 30 as the end of the molting period.

Prior to the initiation of any survey efforts the Service requests documentation on the qualifications of the surveyors, proposed locations for the survey points, verification of audio files to be used, and a schedule. The Service will review these for compliance with the protocol and coverage.

Clearing of habitat outside of the breeding period (October through February) should be completed using the minimization measures listed above as the species is present on the Texas coast year-round.

False Spike (Fusconaia mitchelli) and Guadalupe Orb (Cyclonaias necki)

The endangered false spike is a medium-sized (up to 5.2 inches) freshwater mussel characterized as a rare Texas endemic that only occurs in the Guadalupe basin. The endangered Guadalupe orb is a small-sized (up to 2.5 inches) freshwater mussel. The Guadalupe orb occurs only in the Guadalupe River basin with known populations in Lavaca, Victoria, Refugio, Goliad, and Calhoun counties.

The Service recommends an analysis of the effects of water consumption on the flows of the lower Guadalupe River and its tributaries needed for the facilitys operations, especially during periods of drought.

The Service recommends false spike and Guadalupe orb surveys within the species range and in areas of the watershed that could potentially be impacted by the facilitys operations. Please refer to the Texas Parks and Wildlife Departments 2024 Texas Freshwater Mussel Survey Protocol

Shannon Healy, Environmental Scientist 6

(https://www.fws.gov/sites/default/files/documents/2024-04/2024_texas_freshwater_mussel_survey_protocol_0.pdf) and Guidelines for Aquatic Resource Relocation Plans for Fish and Shellfish, Including Freshwater Mussels (https://tpwd.texas.gov/publications/pwdpubs/media/pwd_lf_t3200_1958_arrp_guideline s_packet.pdf) for more information.

The Service recommends coordination with the Guadalupe-Blanco River Authority for updates on existing survey efforts and current status of development of a Habitat Conservation Plan (https://www.gbra.org/environmental/habitat-conservation-plan/).

Tricolored Bat (Perimyotis subflavus)

The tricolored bat (TCB) has been proposed endangered. To avoid or minimize impacts to the species the Service has established recommended guidelines for projects. Due to geographic and biological differences throughout the species range, the proposed projects location is a critical part of the evaluation for potential impacts. Based on the Services evaluation the proposed Long Mott Generating Station falls within the southern year-round active zone. The Service recommends surveys within tricolored bat habitat prior to implementation of on-the-ground activities or initiation of section 7 consultation. Survey protocols are outlined in the Range-wide Indiana Bat and Northern Long-eared Bat Survey Guidelines (Guidelines) at https://www.fws.gov/library/collections/range-wide-indiana-bat-and-northern-long-eared-bat-survey-guidelines. Survey proposals should be sent to mary_lee@fws.gov for review prior to initiation. Please complete the determination key available through the Services Information for Planning and Consultation system prior to initiating consultation at https://ipac.ecosphere.fws.gov/. The following are the recommended conservation measures for the tricolored bat:

Avoid tree clearing during maternity season (May 1 through July 15). Clearing in the southern year-round active zone should be conducted outside of the maternity season.

To avoid or minimize impacts to the TCB, the Service recommends conducting presence/probable absence (P/A) surveys per the Guidelines prior to the removal of roosting habitat (e.g., trees or culverts). P/A surveys should include a total of 14 acoustic nights per 123 acres, with a minimum of two autonomous recording units (ARUs) over a minimum of 2 calendar nights [Linear projects are 4 acoustic nights per 1 kilometer].

This is the same level-of-effort for the northern long-eared bat (Myotis septentrionalis; NLEB), see page 1 of Guidelines for more details. If P/A surveys are determined to be appropriate by both the project proponent and the local Services Field Office, the optimal year-round survey season dates are May 1 to September 30 (see page 12 and Appendix J of Guidelines). The Service may request year-round survey data in the interest of assessing migration and wintering patterns.

If nighttime work is required, aim lighting at work zone and turn off when not needed, as possible. All permanent lighting should be pointed away from potential habitat, down shielded, and follow the International Dark-Sky Association best management practices.

During the summer, pups are nonvolant and unable to leave the maternal roost tree.

Surveys should be performed with a focus on identifying tricolored bat maternity

Shannon Healy, Environmental Scientist 7

colonies and roost trees. Tricolored bat females primarily roost within leaf clusters and occasionally Spanish moss on living, dying, or recently deceased deciduous and coniferous trees. Currently, all types of trees are considered potential roost habitat. Any tree clearing of potential habitat should be reviewed by project managers.

If maternity roost trees are located, the Service recommends leaving a 1000-foot vegetated buffer for any activity involving construction during the May 1 through July 15 maternity season.

TCBs are known to utilize culverts in this area. All culverts 2 feet by 23 feet or larger should have a visual inspection for bat presence before construction. If any evidence of bats, regardless of species, is found, please contact the Service for further survey recommendations.

Tree removal (i.e., cutting or other means of knocking down, bringing down, topping, or trimming suitable NLEB and/or TCB roost trees) should be conducted as follows (see Bat Activity Periods, Appendix 2):

a. Outside the summer occupancy period for NLEB.

b. Outside the pup season for TCB.

c. Outside spring staging and fall swarming periods within known NLEB and/or TCB spring staging/fall swarming areas (i.e., 5 miles or 3 miles from NLEB or TCB hibernaculum entrances, respectively) in the hibernating range.

d. And, when the extent of tree removal does not exceed the following:

Percent forest cover within 5x5-kilometer grid cell where the project area intersects Tree removal thresholds (acres) with time of year restrictions (see above) 0-9.9 0.5 10.0-19.9 5

20.0-29.9 40 30.0-100 100 Monarch Butterfly (Danaus plexippus)

In December 2024, the Service proposed to list the monarch butterfly as threatened and designate critical habitat. Monarch butterflies breed and migrate throughout Texas. During the breeding season, monarchs lay their eggs on obligate milkweed host plants (primarily Asclepias spp.), and larvae emerge after two to five days, feeding on milkweed and sequestering toxic chemicals as a defense against predators. There are multiple generations of monarchs produced during the breeding season, with most adult butterflies living approximately two to five weeks; overwintering adults enter into reproductive diapause (suspended reproduction) and live six to nine months.

The Texas coast is an important fall migration pathway for the eastern U.S. monarch population in route to the monarchs primary overwintering site in Mexico. Fall migration covers long distances and can last for over two months, with peak migration through South Texas occurring in late October through November. In early spring (February-March), overwintering monarchs break diapause and mate before flying back to the breeding grounds where their offspring start

Shannon Healy, Environmental Scientist 8

the cycle of generational migration over again. For peak migration dates, see https://www.monarchwatch.org/tagmig/peak.html.

The Service recommends conservation of native grasslands and other pollinator habitats by seeding and replanting existing rights-of-way or disturbed sites with native grasses, milkweeds, and nectar plants that are native to the area. We recommend organic gardening that avoids the use of insecticides and herbicides whenever possible to avoid harming monarchs and milkweeds, and employ a targeted approach to pesticide applications when their use is warranted (also see Integrated Pest Management; https://www.epa.gov/ipm/introduction-integrated-pest-management). For right-of-way maintenance, we recommend using a mowing deck height of 12 inches to protect native vegetation communities and combat the establishment of invasive plant species. Additionally, we recommend modifying mowing practices to avoid periods of monarch breeding and migration. During peak fall migration, nectar secreting flowers need to be available and therefore mowing practices should be moderated before this time to allow plants to grow. Therefore, only moderate mowing is recommended September 15 - October 31. For more information on monarch conservation, visit https://www.fws.gov/savethemonarch/ and http://www.mafwa.org/?page_id=2347.

For monarch surveys, the Service recommends looking for and conserving early successional native grasslands or savannahs. The presence of milkweed enhances potential for caterpillars in both spring and fall. Trees can act as nighttime roosts in areas adjacent to high nectar sources.

The Candidate Conservation Agreement with Assurances for transportation right of ways (https://www.fws.gov/sites/default/files/documents/Final_CCAA_040720_Fully%20Executed.pd f) recommends planting six or more milkweeds in a plot and approximately 10 percent cover of nectar secreting plants. A plot is generally 1,500 square feet in size.

The Service appreciates the opportunity to review the proposed project. If you have questions regarding these comments, please contact Mary Kay Skoruppa at 346-815-0009, or by email at mary_kay_skoruppa@fws.gov.

Sincerely, Catrina Martin Assistant Field Supervisor CATRINA MARTIN Digitally signed by CATRINA MARTIN Date: 2025.08.21 09:35:36

-05'00'

Shannon Healy, Environmental Scientist 9

References Bissett, W.T., Jr. 2007. Ecosystem health at the Texas Coastal Bend: A spatial analysis of exposure and response. PhD dissertation, Texas A&M University, College Station, Texas.

Kleiner, D.J. 2020. Calhoun County. Handbook of Texas Online. Texas State Historical Association. https://www.tshaonline.org/handbook/entries/calhoun-county. Accessed July 24, 2025.

Landry, Jr., A.M., D.T. Costa, F.L. Kenyon, K.E. St. John, M.S. Coyne, and M.C. Hadler. 1997.

Distribution of sea turtles in Lavaca and Matagorda Bays, Texas - A preliminary survey of ecology and toxicology of sea turtles as related to Formosa Plastics Corporations wastewater discharge. Final Report submitted to the Environmental Protection Agency, August 1997.

NielsenGammon, J.W., J.L. Banner, B.I. Cook, D.M. Tremaine, C.I. Wong, R.E. Mace, H. Gao, Z.L. Yang, M.F. Gonzalez, R. Hoffpauir, T. Gooch, and K. Kloesel. 2020. Unprecedented drought challenges forTexas water resources in a changing climate: What do researchers and stakeholders need to know? Earth's Future 8(8):1-20. https://doi.org/10.1029/2020EF001552.

Accessed July 24, 2025.

Sager, D.R. 2002. Long-term variation in mercury concentrations in estuarine organisms with changes in releases into Lavaca Bay, Texas. Marine Pollution Bulletin 44(8):807-815.

Tunnell, J.W., K.H. Dunning, L.P. Sheef, and K.M. Swanson. 2020. Measuring plastic pellet (nurdle) abundance on shorelines throughout the Gulf of Mexico using citizen scientists:

Establishing a platform for policy-relevant research. Marine Pollution Bulletin 151:110794.

Virginia Institute of Marine Science. 2023. Sea-level report card for Rockport, Texas.

https://www.vims.edu/research/products/slrc/localities/rotx/index.php. Accessed July 24, 2025.