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Results Released of Two-year Growler Sound Study
on the Olympic Peninsula

Locations of the 3 monitoring sites and proximity to the Olympic MOA. The Third Beach and River Trail sites (red symbols) are within the Park. The Hoh Watershed site is adjacent to, but not within, the Park boundary. Click on map for larger image.

The study was conducted by Lauren Kuehne, MSc Research Scientist at the University of Washington’s College of the Environment School of Aquatic and Fishery Sciences. Ms. Kuehne has undertaken one of the only scientific studies of the soundscape on the Olympic Peninsula. Ms. Kuehne “sought to answer two questions: 1) What are the current noise levels and contributions of different aircraft on the Olympic Peninsula soundscape? and 2) How might these levels change with proposed increases in military training and operations?”

The study captured sound data from three areas within the Olympic National Park and adjacent to the Military Operations Area (MOA) for the Navy training activities that fly out of Naval Air Station Whidbey Island (NASWI). The three study locations on the west side of the Olympic Peninsula were: “Third Beach (elevation 64 m), River Trail (199 m), and Hoh Watershed (28 m).” The study recorded and distinguished commercial aircraft, military aircraft and helicopters. The study included capturing data from the Navy Boeing EA-18G (“Growler”) aircraft in 2017 and 2018, before the current increase of 36 added aircraft (2019).

As the Olympic Peninsula shoulders the burden for the country of training pilots on the new aircraft, Ms. Kuehne’s study shows that ground monitoring of noise is feasible and can produce reliable data that shows impacts, and can and should be used to drive mitigation strategies for endangered species like the Northern Spotted Owl and Marbled Murrelet, as well as rural residents’ health. With the decision to increase the Navy fleet from 82 to 118 jets (Record of Decision for Growler Environmental Impact Statement – 2019), monitoring the increase in noise and related impacts becomes more imperative. Read Ms. Kuehne’s report.

Excerpts of results of Ms. Kuehne’s study:

  • “The data were compared with the Whidbey Island airfield public notice of flights, 83% of which are the Growler aircraft.
  • Of the 4,644 flight events identified, of these, 85% were classified as military, 8% commercial, 6% propeller and <1% were helicopters.
  • On the busiest days, we recorded an average of up to 70–85 flight events per location.
  • The maximum number of flight events recorded on a single day at locations was 73 (Hoh Watershed), 104 (River Trail) and 81 (Third Beach).
  • The duration of time in each day and hour that military aircraft were audible was highly correlated across the three locations, indicating flight activities impacted a large geographic area at any given time.
  • Military aircraft are a dominant contributor to the soundscape of the Olympic Peninsula, representing 85% of the total time aircraft are audible.
  • Percent time audible was substantial during daytime hours, particularly at the coastal sites, which averaged 12% audible during daytime hours across all 40 recording days. However, to achieve this average level meant that on some individual days the percent time audible during these hours was far greater (e.g., 49–52% of the time). Individual locations can experience in the range of up to 80–100 events in a single day.”
  • Data showed that areas outside of the MOA are clearly impacted, with the Hoh River location averaging 9–12% audible during daytime hours (with a maximum of 52% recorded on one sampling day-hour).
  • The River Trail location, positioned 1.8 km outside the MOA, receives consistent noise from military aircraft, indicating that the noise footprint extends well beyond the MOA.

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