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Stevens County narrows marking rules for temporary meteorological towers, removes daytime strobe requirement
Summary
After a lengthy public hearing with pilots and wind‑project representatives, the Stevens County Board approved enhanced guide‑wire markings for temporary meteorological (MET) towers but voted to remove a county condition requiring daytime strobe lights, citing engineering and manufacturer concerns.
The Stevens County Board of Commissioners on Tuesday amended conditions on a previously approved interim use permit (IUP) for temporary meteorological towers used by wind developers, requiring high‑visibility sleeves and a standard two‑ball marker configuration on outer guy wires while removing a county condition that had required daytime strobe lighting.
The change came after a public hearing in which Tenaska/Cordelio project staff argued that manufacturer guidance and tower design make both a large increase in spherical markers and nonstandard daytime strobes infeasible, and area agricultural pilots urged stricter visibility measures to reduce the risk of collisions.
Jackson Morgan, who identified himself as responsible for the project Tenaska and Cordelio Power are developing in Stevens County, told commissioners that the towers “employ 2 ... aviation orange colored spherical marking balls on each of the 4 outer guy wires for a total of 8 markings” and that the manufacturer, NRG Systems, warned that adding the dozens of extra marking balls requested by the county could “compromise the entire tower structure” because of added wind and ice load. Morgan proposed, and the company committed to, a package of measures that included the eight aviation‑orange balls plus high‑visibility marking sleeves on outer guy wires to a height of 25 feet and the usual nighttime obstruction lighting required by federal guidance.
Pilots and aviation safety advocates spoke against weakening the original county language. Charity Carlson of Carlson Haggie Aviation and several local aerial applicators described previous accidents involving unmarked or poorly marked wires and urged the board to keep the more prescriptive language on the record. “The original conditions weren’t extreme,” Carlson said. “They reflect FAA recommendations ... that are based on real incidents, injuries, and fatalities.” Other pilots, including representatives from Tasco and Schwenk Air, said clearer markings and lights improve situational awareness when smoke, low sun or other visibility challenges occur.
The commissioners voted in two separate steps. First they adopted revised guide‑wire marking language proposed by the developer—requiring two aviation‑orange spherical markers per outer guy wire plus high‑visibility sleeves installed on the outer guy wires to 25 feet above ground—by voice vote. Later, after debate about whether the county should require a daytime strobe light on the towers, the board voted to remove the daytime strobe requirement from the IUP conditions. The final motion removing the daytime strobe passed by voice vote; commissioners also recorded that they were encouraging the applicant to continue pursuing engineering options and FAA/MnDOT coordination for additional visibility measures.
The county administration read the IUP condition under review into the record before the hearing; the condition originally required MnDOT approval for installation of alternating red/white spherical markers, yellow reflective sleeves from each guy‑wire base up to the first marker, and a daytime strobe on top of the tower. The board’s final action keeps prescriptive guide‑wire markings in the permit (balls + sleeves) but leaves the daytime strobe out of the binding condition, while recording the board’s interest in pursuing additional safety options with the applicant.
Why it matters: agricultural pilots operate at low altitudes and repeatedly told the board that low, temporary towers and their guy wires are hard to see from the cockpit; pilots and safety advocates said stronger, enforceable requirements will reduce the risk of fatal collisions. Developers said they will follow federal and state guidance and manufacturer recommendations; they also indicated they will continue to seek engineering solutions for additional lighting if feasible.
The record for the hearing includes letters and manufacturer guidance from NRG Systems, FAA advisory material and MnDOT references submitted by the applicant and several witnesses; these were entered as part of the public hearing record.
What’s next: the developer said it will proceed with the marking method approved by the board and continue coordination with the Minnesota Department of Transportation and the FAA. The board asked county staff to remain engaged on technical feasibility and to request follow‑up documentation from the applicant if additional lighting or other safety devices are engineered.
