Officials Advise Limiting Consumption of Fish from Applegate Lake

Applegate Lake has been added to the list of Oregon reservoirs with fish showing elevated levels of mercury in their tissues. As such, the Oregon Health Authority (OHA) has advised a strict limit on the consumption of fish from Applegate until further notice.

Bass, Crappie, Bluegill, Yellow Perch Affected

OHA testing of bass, crappie, bluegill, and yellow perch in Applegate Lake showed unhealthy levels of mercury in all species. Smallmouth bass from Applegate showed mercury levels three times greater than the usual threshold for safe consumption. The bluegill and black crappie samples were just above advisory levels. Yellow perch were not actually tested, but because their life cycles are very similar to basses’, they have been added to the list as a precaution. Rainbow trout from the lake are considered safe to eat.

Similar advisories have been in effect for fish from Emigrant Lake for nearly twenty years. High mercury levels have been found all across the Rogue River Basin, particularly in pikeminnows from the Rogue River itself.

Photo credit: Derek Severson / Foter / Creative Commons Attribution-NonCommercial-NoDerivs 2.0 Generic (CC BY-NC-ND 2.0)

Applegate Lake
Photo credit: Derek Severson / Foter / Creative Commons Attribution-NonCommercial-NoDerivs 2.0 Generic (CC BY-NC-ND 2.0)

A statewide OHA advisory on bass consumption is expected soon. The only two Oregon lakes whose bass are safe to eat are Henry Hagg Lake and Paulina Lake.

Toxic Mercury

In high enough levels, mercury is toxic to all humans, and even at low levels, it can have ill effects on health. The element is especially dangerous to fetuses, as it can cause permanent problems with brain development and has been linked to autism, lower IQs, and other developmental problems in children. Mercury chemically bonds to fish muscle tissues, and cannot be removed or reduced through any cleaning or cooking method.

As such, the OHA advises pregnant women, nursing mothers, and children to eat no more than two servings per month of bass (large- and smallmouth) and yellow perch and no more than four servings per month of bluegill and crappie. Normal adult humans are advised to eat no more than five servings of bass and yellow perch per month, and no more than 13 servings of bluegill and crappie. (A “serving” here is roughly the size/thickness of the average adult’s hand.)

The cause of the elevated mercury levels in Applegate Lake has not yet been determined. That truckload of old thermometers I dumped in there last fall probably didn’t help, however.

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