Spill’s Effects Could Linger for 50 Years : Environment: The upper Sacramento River’s aquatic life may need 20 years to return to levels of last July, before a train derailed and spilled pesticide, a study says.

It could take 50 years for the ecosystem of the upper Sacramento River to fully recover from the toxic pesticide spilled in the waterway by a derailed Southern Pacific train, according to a state study released Tuesday.

The report, which details plans for assessing damage from the spill and monitoring the recovery, predicted that some species will come back within a relatively short time, but that it will take decades before the river region returns to normal.

The spill of toxic metam-sodium on July 14 destroyed nearly all aquatic life along a 45-mile stretch of river and killed or damaged a huge swath of vegetation along its banks. Animals that depend on the river for food have either starved to death or moved into areas that now face overpopulation, according to the study.

“When food sources are gone, they’re going to be really in trouble,” said Gary Stacey, a Department of Fish and Game environmental services supervisor who helped prepare the report. “We expect population crashes over the next couple of years.”

The study estimates it will take 20 years for aquatic life in the river to return to pre-spill levels.

First the algae, moss and insect life that provides food for fish in the river must recover, a process that will take two to five years. It could take 10 to 12 more years to replace the wild trout population, which included some fish that were 7 years old. Sucker fish, some of which were believed to be more than 15 years old, will take even longer, the report said.

Scientists expect the forest along the river to be the slowest to recover, taking between 20 and 50 years.

Some trees and bushes are still sick and dying from the metam-sodium, a pesticide and soil fumigant used in agriculture. Among the trees killed by the spill were cottonwoods that live more than 40 years.

The recovery of wildlife in the forest, such as otters, osprey and bald eagles, will depend largely on the ability of aquatic life and the forest to regenerate, the report said. Estimates were it could take five to 25 years for the recovery of animals in the spill area.

“Recovery of wildlife populations to pre-spill levels will depend on restoration of injured habitat, re-establishment of an adequate food base and the potential long-term effects of exposure to metam-sodium,” the report said.

Much of the study sets forth a plan for coming up with a dollar figure for the damage caused by the spill. So far, state officials say they have no estimate, in part because the chemical is still taking a toll on the forest and its wildlife. However, the figure is likely to be quite large and the state will seek to recover the full amount from Southern Pacific, officials say.