In this article from today’s Bee a fuller story of the fish dying from dissolved gas supersaturation at Nimbus emerges and it is not a good one, and the key quote here is; “However, if climate change causes more episodes of extreme weather that result in more-frequent high-water years, Canaday acknowledged, supersaturation of rivers could become a more familiar problem in California.”
Here is an excerpt.
Gigantic fish kill
State confronts a new threat in gas-charged water blamed for Nimbus fingerling deaths
By Edie Lau -- Bee Science WriterPublished 12:01 am PDT Sunday, May 21, 2006
California, often a leader in setting environmental standards, has none for a water-quality problem that is contributing to the fish killed at Nimbus Hatchery.
The problem, known as dissolved gas supersaturation, causes gas-bubble disease in fish. Divers experience a similar sickness known as "the bends."
Gas supersaturation has been the subject of numerous workshops and studies in the Pacific Northwest for decades. At least 20 years ago, the U.S. Environmental Protection Agency recommended states set limits on dissolved gases in waterways.
But the issue is new to California, coming to the fore only since workers at Nimbus Hatchery began in the past week to remove dead salmon by the tens of thousands a day from their concrete troughs on the American River.
Jim Canaday, a senior environmental scientist at the state Water Resources Control Board, said that up to now, "It hasn't been a problem. ... It's something we'll have to look into," he added.
The hatchery fish, fingerling salmon that during a normal spring would be planted in the Bay Area to mature in the ocean, are suffering from a mix of woes.
Two are infections: One, called coldwater disease, can be treated with antibiotics. The other, infectious hematopoietic necrosis, is a viral infection for which there is no treatment.
The third is gas bubble disease, which can kill or stress fish, making them more vulnerable to other illnesses.
About 1.2 million out of 5.1 million Nimbus salmon have died in the past month. The hatchery was established to produce 4 million salmon annually to compensate for a loss of spawning habitat due to the construction of Nimbus and Folsom dams 50 years ago.
State Department of Fish and Game officials attribute the gas-bubble disease to frequent and prolonged periods of exceedingly high runoff last winter and this spring, caused by abundant rainfall and snowmelt. Massive volumes of water have been coming out of the Folsom and Nimbus dams off and on since Christmas.
