119-S-1377 Investigative Journalist Impact Analysis

Summary

The bill sets a statutory floor of 150 horses in the South Unit, requires a “genetically diverse” herd, directs the Secretary to produce a cost‑effective management plan within 120 days, restricts removals to emergencies, public‑safety needs, or actions tied to maintaining genetic diversity, and mandates annual public reporting. This codifies the herd’s permanence after NPS ended its separate livestock EA process in 2024 and continued active management (e.g., contraception, GPS collars). The economic signal is stability for a marquee visitor experience; the operational signal is sustained spending on contraception, monitoring, and likely genetic augmentation. Environmentally, peer‑reviewed work shows horses can reduce herbaceous biomass and degrade riparian sites and wildlife access to water in arid systems, though not all studies find shifts in plant community composition. The bill’s “no adverse impact” clause will require tight implementation to reconcile a fixed minimum herd with NPS’s ‘unimpaired’ mandate. [1]Congress.gov (Library of Congress) — Text: S.1377 — 119th Congress (2025–2026)[6]National Park Service — Theodore Roosevelt National Park Terminates Livestock P…[7]National Park Service — Horses of Theodore Roosevelt National Park (management…[3]U.S. Geological Survey (Western North American Naturalist, 2018) — Effects of f…[4]USDA Forest Service (Journal of Wildlife Management, 2021) — Lentic Meadows and…[8]Journal of Mammalogy (Oxford University Press) — Interactions between Feral Hor…[5]Legal Information Institute (Cornell Law School) — 54 U.S.C. §100101 – NPS ‘uni…

Economic Effects

Direct fiscal impacts to the federal government are uncertain at this stage; local effects relate to tourism continuity and management outlays.

• Visitor spending near TRNP: In 2022 the park saw 668,679 visits and ~$47.7M in local visitor spending (supporting ~570 jobs). Sustaining a visible horse herd likely preserves, rather than expands, this draw, but it reduces the risk of abrupt visitor‑experience changes from complete removal. [2]National Park Service — National Park Visitation Sets New Record as Economic En…
• Program costs: Long‑term fertility control and monitoring are recurring expenses. BLM experience (used here as a benchmark) places one‑year PZP at roughly $25–$35 per dose plus delivery, with multi‑year formulations or gathers far costlier; modeling found fertility control can lower variable operating costs 15–18% versus removal‑heavy strategies. TRNP currently uses GonaCon, which can suppress fertility for multiple years with boosters. [9]Bureau of Land Management — BLM IM 2009-090: Population-Level Fertility Control…[10]Web search · turn 16 #2[11]U.S. Geological Survey (Journal of Wildlife Management, 2007) — Economic benefi…[7]National Park Service — Horses of Theodore Roosevelt National Park (management…
• Operational burden: To affect population growth, agencies typically need to treat ≥75% of mares—labor‑intensive in rugged terrain—implying sustained staffing/contract support. [12]Bureau of Land Management — Top 5 things to know about wild horse and burro fer…
• Genetic management: Peer‑reviewed analyses of the TRNP herd report low diversity and recent inbreeding, implying periodic importation of outside stock and associated quarantine/veterinary costs to meet the bill’s “genetically diverse” standard. [13]PubMed (PLOS ONE) — Genetic diversity and origin of TRNP feral horses (2018)[14]PubMed (Ecology and Evolution, Wiley) — Population genomics of TRNP feral horse…
• Federal scoring: Congress.gov shows no CBO estimate yet; near‑term federal budget effects are unscored and depend on how NPS implements contraception, monitoring, and any translocations. [15]Congress.gov (Library of Congress) — S.1377 overview and actions (hearing 12/09…

Social Effects

• Heritage and identity: NPS has long managed TRNP horses as a historic demonstration herd (they are not protected by the 1971 Wild Free‑Roaming Horses and Burros Act on NPS lands). Codifying their presence aligns with on‑the‑ground expectations and avoids whiplash from policy reversals. [16]National Park Service — Horse Background and History – TRNP (demo herd; WH&B Ac…
• Community/tourism stability: Keeping a visible herd reduces uncertainty for Medora‑area operators who market wildlife viewing. While quantifying horses’ marginal draw is difficult, avoiding removal protects an established visitor experience. [2]National Park Service — National Park Visitation Sets New Record as Economic En…
• Government‑to‑government engagement: The terminated EA documented consultation with affiliated Tribes and state officials. Future genetic and contraception decisions will benefit from that framework. [17]Web search · turn 1 #2

Environmental Effects

Evidence indicates both localized ecological risks and context‑dependent outcomes.

• Vegetation and soils: Studies across western rangelands find free‑roaming horses reduce herbaceous biomass and can increase soil disturbance/compaction and alter invertebrate communities—effects that can be pronounced in arid systems. [3]U.S. Geological Survey (Western North American Naturalist, 2018) — Effects of f…[18]U.S. Geological Survey (Journal of Arid Environments, 2006) — Effects of feral…
• Riparian/wetland function: Time‑lapse and field studies show horse and cattle grazing can impair spring‑fed meadows’ hydric vegetation and soil integrity when rest/recovery is insufficient. [4]USDA Forest Service (Journal of Wildlife Management, 2021) — Lentic Meadows and…
• Wildlife water access: Experimental and observational work documents avoidance or displacement of native ungulates (e.g., bighorn sheep; similar patterns for pronghorn) at waters used by horses, elevating vigilance and potentially reducing fitness during hot, dry periods. [8]Journal of Mammalogy (Oxford University Press) — Interactions between Feral Hor…[19]Web search · turn 17 #1
• Context matters: A multi‑site analysis did not detect shifts in plant community composition despite reduced biomass, suggesting impacts vary with site productivity and management. Monitoring must be tailored to TRNP’s badlands conditions. [3]U.S. Geological Survey (Western North American Naturalist, 2018) — Effects of f…
• TRNP specifics: NPS reports continued contraception (GonaCon), GPS collar studies on movements, and periodic roundups—tools that can mitigate impacts if coverage is sustained and habitat data guide use‑area management. [7]National Park Service — Horses of Theodore Roosevelt National Park (management…

Temporal Analysis

1. 0–12 months: NPS must publish a management plan within 120 days; expect immediate continuation of darting/roundups and a formal genetic‑management roadmap (e.g., identifying donor stock, quarantine). Visitor experience remains stable. [1]Congress.gov (Library of Congress) — Text: S.1377 — 119th Congress (2025–2026)[7]National Park Service — Horses of Theodore Roosevelt National Park (management…
2. 1–5 years: Recurring contraception cycles (boosters) and possible introductions of outside mares/stallions to raise diversity; adaptive monitoring of range condition, waters, and wildlife interactions. Budget needs likely baseline into park ops. [20]Wildlife Research (CSIRO Publishing) — Four-year contraception rates for GonaCo…[14]PubMed (Ecology and Evolution, Wiley) — Population genomics of TRNP feral horse…
3. 5+ years: Outcomes bifurcate on management quality. High contraception coverage and targeted introductions can hold growth near statutory minimum while limiting ecological pressure; lapses could produce resource conflicts and emergency removals despite statutory constraints. [12]Bureau of Land Management — Top 5 things to know about wild horse and burro fer…

Unintended Consequences

• Statutory floor vs. ‘unimpaired’ standard: A hard minimum (150) may constrain NPS flexibility during drought or acute habitat stress, potentially clashing with the Organic Act’s conservation mandate unless the plan proves impacts are not “adverse.” This could invite litigation if monitoring shows resource impairment. [1]Congress.gov (Library of Congress) — Text: S.1377 — 119th Congress (2025–2026)[5]Legal Information Institute (Cornell Law School) — 54 U.S.C. §100101 – NPS ‘uni…
• Genetic augmentation trade‑offs: Importing horses to boost diversity raises biosecurity, disease‑screening, and social‑behavior risks, plus recurring costs; failure to augment risks inbreeding depression flagged by recent genomics work. [13]PubMed (PLOS ONE) — Genetic diversity and origin of TRNP feral horses (2018)[14]PubMed (Ecology and Evolution, Wiley) — Population genomics of TRNP feral horse…
• Implementation capacity: Achieving ≥75% mare treatment annually/biannually is labor‑intensive; staffing or budget shortfalls could erode effectiveness and trigger population spikes. [12]Bureau of Land Management — Top 5 things to know about wild horse and burro fer…
• Spillover to other species/sites: Documented competition at scarce waters suggests managers may need seasonal closures, exclosures, or water developments—costs and controversies not explicitly addressed in the bill. [8]Journal of Mammalogy (Oxford University Press) — Interactions between Feral Hor…

Assessment

Overall stance: neutral. The bill would stabilize a valued visitor experience and provide procedural guardrails (plan + monitoring) but obligates NPS to deliver sustained, well‑funded fertility and genetic management to keep ecological impacts within the “no adverse” limit. Success depends less on the statute’s language than on execution (coverage rates, habitat monitoring, and transparent reporting) under the Organic Act’s conservation standard. [1]Congress.gov (Library of Congress) — Text: S.1377 — 119th Congress (2025–2026)[5]Legal Information Institute (Cornell Law School) — 54 U.S.C. §100101 – NPS ‘uni…

Sourcing

Selected primary and authoritative sources used in this analysis.

• Congress.gov bill text and status for S.1377; committee hearing on December 9, 2025. [1]Congress.gov (Library of Congress) — Text: S.1377 — 119th Congress (2025–2026)[15]Congress.gov (Library of Congress) — S.1377 overview and actions (hearing 12/09…
• NPS: TRNP management updates (GonaCon, GPS collars, roundup) and termination of the Livestock Plan EA. [7]National Park Service — Horses of Theodore Roosevelt National Park (management…[6]National Park Service — Theodore Roosevelt National Park Terminates Livestock P…
• NPS: Historic/demo‑herd context and non‑applicability of the 1971 Act on NPS lands. [16]National Park Service — Horse Background and History – TRNP (demo herd; WH&B Ac…
• NPS economics: TRNP visitation and visitor‑spending effects. [2]National Park Service — National Park Visitation Sets New Record as Economic En…
• Genetics: Peer‑reviewed assessments of TRNP herd diversity and inbreeding. [13]PubMed (PLOS ONE) — Genetic diversity and origin of TRNP feral horses (2018)[14]PubMed (Ecology and Evolution, Wiley) — Population genomics of TRNP feral horse…
• Ecology: Biomass/plant community, soils/invertebrates, riparian function, and wildlife water‑site interactions. [3]U.S. Geological Survey (Western North American Naturalist, 2018) — Effects of f…[18]U.S. Geological Survey (Journal of Arid Environments, 2006) — Effects of feral…[4]USDA Forest Service (Journal of Wildlife Management, 2021) — Lentic Meadows and…[8]Journal of Mammalogy (Oxford University Press) — Interactions between Feral Hor…
• Management costs/effectiveness: BLM policy memorandum on PZP costs and USGS cost‑benefit modeling; multi‑year efficacy and coverage benchmarks. [9]Bureau of Land Management — BLM IM 2009-090: Population-Level Fertility Control…[11]U.S. Geological Survey (Journal of Wildlife Management, 2007) — Economic benefi…[20]Wildlife Research (CSIRO Publishing) — Four-year contraception rates for GonaCo…[12]Bureau of Land Management — Top 5 things to know about wild horse and burro fer…
• Legal context: NPS Organic Act unimpaired standard (54 U.S.C. §100101). [5]Legal Information Institute (Cornell Law School) — 54 U.S.C. §100101 – NPS ‘uni…