“Model or Miss the Boat” – Sixth Circuit Requires Site-Specific Hydrologic Modeling and Full Rule 26 Compliance for Flood-Causation Experts

Introduction

In Eugene Baker v. Blackhawk Mining, LLC, No. 24-5490 (6th Cir. 2025), dozens of Eastern Kentucky residents sued Pine Branch Mining, LLC (“Pine Branch”) after a once-in-a-century rain event devastated their community. The plaintiffs pleaded negligence per se, alleging that unlawful mine-site reclamation amplified the flood. Their entire causation case rested on one expert, Dr. Scott Simonton. The district court struck his report under Federal Rule of Evidence 702 (“Daubert”) and Rule 26(a)(2)(B), then entered summary judgment for the defendant.

The Sixth Circuit affirmed, crafting a precedent that squarely addresses hydrologic-flood litigation: a plaintiff who alleges that surface-mine conditions worsened downstream flooding must (1) supply site-specific, scientifically modeled data that survives Daubert scrutiny and (2) deliver a complete, timely expert disclosure under Rule 26, or risk losing at summary judgment.

Summary of the Judgment

Expert Exclusion. The panel (Chief Judge Sutton, Judges Bush & Murphy) held that Dr. Simonton’s preliminary report was inadmissible because it relied on remote studies, anecdotal observations and lacked any hydraulic or hydrologic modeling – the industry standard for flood causation. It therefore failed FRE 702’s reliability prongs.
Rule 26 Violation. The same report was excluded for disclosure defects: incomplete opinions, missing data/exhibits, and no comprehensive prior-testimony list. Rule 37(c)(1) made exclusion “mandatory” absent substantial justification or harmlessness.
No Causation Evidence. With the sole expert gone, Kentucky law’s requirement of expert testimony on complex flood causation could not be met; aerial photos and inspection notices were deemed insufficient.
Affirmed Summary Judgment. The Sixth Circuit affirmed the district court’s grant of summary judgment to Pine Branch on the negligence-per-se claim.

Analysis

Precedents Cited

Kumho Tire v. Carmichael, 526 U.S. 137 (1999) – flexible Daubert reliability factors applied.
Pluck v. BP Oil Pipeline, 640 F.3d 671 (6th Cir. 2011) – exclusion where expert lacked exposure data and failed to rule out alternatives.
Baker v. Chevron, 533 F. App’x 509 (6th Cir. 2013) – exclusion for failure to conduct vapor-pathway analysis and untimely supplementation.
Newell Rubbermaid v. Raymond Corp., 676 F.3d 521 (6th Cir. 2012) – “red flags” list (anecdotal evidence, improper extrapolation, etc.).
Adkins v. Marathon Petroleum, 105 F.4th 841 (6th Cir. 2024) – rigor demanded in Rule 26 expert disclosures.

The court treated these earlier opinions as stepping-stones: Simonton’s report bore every “red flag” previously condemned – lack of testing, improper extrapolation, failure to eliminate alternative causes, and deficient disclosure – making exclusion almost inevitable under circuit precedent.

Legal Reasoning

Reliability Test. The panel stressed that flood hydrology is “inherently complex” and almost always requires computer-based models (HEC-RAS / HEC-HMS). Simonton offered none, contradicting his own prior testimony that modeling is “the standard.”
Relevance to Site. Studies from Pikeville, Middlesboro, and Mingo County held little weight because River Caney’s terrain, rainfall and watershed geometry were unique. Site-specificity became a decisive relevance criterion.
Alternative Causes. The expert’s failure to address the historic 14-16 inch rainfall as a potential superseding cause violated the differential-etiology requirement emphasized in Pluck and Tamraz.
Disclosure Rigor. Echoing Adkins and Brainard, the panel reaffirmed that a “preliminary” summary cannot stand in for the “complete statement” demanded by Rule 26(a)(2)(B). Late production of underlying materials did not cure the defect.
Substantive State Law. Kentucky law classifies flood-causation questions as outside lay competence; hence Federal courts sitting in diversity must require expert proof (Erie doctrine).

Impact of the Decision

The ruling has several forward-looking effects:

Hydrology Litigation Playbook. Plaintiffs alleging that land-use disturbances worsened flood damage must now budget for sophisticated hydrologic modeling and early, meticulous expert reports. “Eyeballing” aerial photos will not suffice.
Tightened Gatekeeping. The Sixth Circuit reinforces a demanding stance on Rule 702 reliability for environmental-tort experts, likely influencing district courts within the circuit to scrutinize modeling, site data, and alternative-cause analysis more aggressively.
Rule 26 Enforcement. By declaring exclusion “mandatory” in the absence of substantial justification or harmlessness, the opinion signals that incomplete or “placeholder” expert reports are a high-risk strategy.
Industry Reliance. Mining, energy and infrastructure defendants gain a roadmap for challenging causation theories: attack site-specific data gaps, modeling omissions, and disclosure errors.
Settlement Dynamics. Plaintiffs’ counsel must now ensure technical robustness early, likely increasing upfront costs but also clarifying meritorious claims sooner, potentially reducing protracted litigation.

Complex Concepts Simplified

Daubert / Rule 702. Federal judges act as “gatekeepers.” They ask: (1) Is the expert qualified? (2) Did the expert use reliable methods? (3) Are those methods properly applied to the facts? If any answer is “no,” the jury never hears the testimony.
HEC-HMS & HEC-RAS. These are U.S. Army Corps of Engineers computer programs. HEC-HMS simulates rainfall-runoff processes; HEC-RAS models river hydraulics. Together, they estimate how much water flows where, and with what force – critical in flood causation.
Negligence per se. A shortcut liability theory: if a defendant violates a safety statute/regulation and that violation causes the plaintiff’s harm, negligence is automatically established. Plaintiffs still must prove causation and damages.
Rule 26(a)(2)(B). The federal rule that forces parties to reveal expert opinions in detail: the “who, what, why, and how,” plus all relied-upon data, exhibits, prior testimony and compensation. Think of it as full disclosure so nobody is ambushed at trial.

Conclusion

Baker v. Blackhawk Mining crystallizes two intertwined principles: (1) modern flood-causation testimony must be grounded in site-specific hydrologic modeling and withstand rigorous Daubert scrutiny; (2) Rule 26’s detailed disclosure requirements are not optional or flexible – shortcomings will lead to exclusion and, frequently, to judgment for the opposing party.

For litigants across the Sixth Circuit—and likely beyond—the message is unmistakable: when science drives causation, courts will insist on genuine science, delivered on time. Anything less is, as the court effectively put it, “too great an analytical gap” to cross.