EGLE engineer testifies Edenville (Wixom Lake) Dam failed Michigan'spillway standard before May 2020 failure

Lucas Trumbull, the manager of field operations, engineering and enforcement in the Michigan Department of Environment, Great Lakes and Energy's (EGLE) dam-safety unit, told a Midland County courtroom on Jan. 13 that EGLE's hydraulic calculations completed in late January and early February 2020 indicated the Edenville (Wixom Lake) Dam could not meet the state'required design flood known as "one-half PMF." Trumbull said he shared spreadsheet calculations with outside consultants for confirmation and that the department's conclusion was finalized in early February 2020.

Trumbull testified that agency communications with the dam owner (Boyse Hydro) and the incoming owner group (4 Lakes Task Force) began shortly after FERC revoked the federal license in 2018 and that EGLE repeatedly sought technical inputs (gate geometry, gate-opening measurements and historic studies) necessary to confirm hydraulic and hydrologic assumptions. "EGLE confirmed the rating curve ... and concluded definitively that the dam lacked spillway capacity to convey the design flood one-half PMF," Trumbull read into the record from his timeline of Feb. 4, 2020.

The plaintiffs introduced a 2018 Federal Energy Regulatory Commission (FERC) inspection report that concluded the project did not meet FERC engineering dam-safety standards "due to inadequate spillway capacity" and estimated the facility could convey roughly 50% of PMF. Trumbull repeatedly distinguished the federal PMF standard from Michigan's statutory one-half PMF metric, explaining that hydrologic conventions (dividing PMP versus other methods) can produce different numeric flows even when people use similar phrases such as "50% of PMF." He told the court that EGLE required confirmation from its hydrologic specialists and dam-safety staff before accepting consultant calculations.

Trumbull described exchanges with Boyse and consultants including Perkypile and the Spicer Group. He said Spicer's written memo (Sept. 2019) and the owner's early reports expressed concern the dam could not be operated to meet spillway-capacity standards without repairs. Trumbull also testified that Spicer had not produced detailed supporting calculations to EGLE when Spicer asserted the dam was likely not compliant, which prompted EGLE to request geometry and gate-opening data and run its own hydraulic spreadsheets.

Gate testing performed in June 2019 and later field measurements informed rating-curve revisions. Trumbull explained technical distinctions used in the calculations: weir versus orifice flow, gate-opening heights observed in the field (7 feet during the May 2020 event in some bays) and the discharge coefficients used to translate those geometries into cubic feet per second. EGLE's spreadsheets shown at trial calculate combined spillway discharges of roughly 21,000 cfs under observed gate-opening scenarios before overtopping, short of the roughly 25,000 cfs one-half PMF target used in state analyses.

Trumbull said the department also factored freeboard and wave run-up into final compliance discussions. He and counsel discussed that the statutory rule requires considering freeboard, and that preliminary freeboard estimates (Trumbull said he used a preliminary US Bureau of Reclamation method) suggested several feet of freeboard would be required at design flood. "Assuming this stands, the dam would be about 4,000 to 5,000 CFS short of passing one-half PMF with no freeboard at the low point in the earthen embankments," Trumbull wrote in an internal email he introduced at trial.

On process and response, Trumbull told the court EGLE considered but did not order a preemptive drawdown of Wixom Lake before the May 2020 failure. He listed the factors that influenced that decision: (1) prior analyses (a 2013 owner report) and EGLE's own quick comparison of storage volume versus flood volume suggested a pre-drawdown would provide only modest benefit for a PMF-scale event; (2) plans and designs the 4 Lakes Task Force and its consultants were making toward upgrades and their stated schedules and funding strategies; and (3) environmental and permitting impacts associated with lowering an impoundment. In an email he introduced, Trumbull wrote that "we will communicate the hydraulic deficiency to Boyse and FLTF soon." The department's permit records show a 2020 permit allowing refill to normal summer pool (6 75.8 NAVD88) was issued under the inland lakes and streams statutes (part 301) after interagency review.

Trumbull acknowledged that earlier FERC documents used urgent language about the hazard posed under FERC criteria. He told the court that the FERC reports and the state-level analysis are related but apply different standards and that FERC could have ordered different interim measures if it had chosen to do so under its federal authority. On post-failure review, Trumbull said EGLE later received additional model outputs and files from the independent forensics team and that he augmented his earlier spreadsheets with some IFT-provided inputs in 2022 to cross-check results.

The testimony anchored Trumbull's description of a sequence: owner and consultant studies (2013 onward), FERC findings (2018), field inspections and gate tests (2019), EGLE requests for supporting hydraulic inputs, EGLE's internal calculations and a Feb. 2020 determination the dam did not meet the state one-half PMF spillway requirement, and the May 2020 failure that occurred before the owner- and task-force-led repair schedule could be completed.

The hearing continues with cross-examination of technical spreadsheets and further questioning on how freeboard, gate-operation limits and wave run-up affect statutory compliance.