For years, the federal government spent more than $700 million on habitat restoration in the Columbia River Basin. The effort was meant to improve the population of salmon and steelhead that were endangered by hydroelectric dams.

Experts have dubbed the project as the largest and most expensive habitat restoration program in the country with the extensive effort and cost having to do with the program being the focus of federal management plan to relieve the damages brought about by the dams to the fish.

Critics, however, said that depending heavily on habitat improvement is not sufficient for restoring wild fish runs and getting them off of the endangered species list. Other options to improve the population have also been suggested including breaching the dams and spilling more water.

The plan has undergone changes over the past two decades after it has been litigated in court. The latest version is also facing legal challenges and is set for hearing on Tuesday.

Federal officials defended the plan by citing the record number  of sockeye salmon, coho and chinook that returned last year, which they say can be attributed to the improved habitat.

Many of the 13 protected runs of salmon and steelhead, however, scarcely hang on and majority of the returning fishes were not actually born in the wild but in hatcheries, prompting critics to urge for the breaching of the four dams.

Before the European settlement, there were millions of steelhead and salmon that returned annually to the Columbia and its tributaries. Mining, overfishing, logging, pollution and water diversions, however, has led to the plummeting population of the salmon.

The management plans include reduction of the impacts of fish that were artificially bred on the wild ones, improvement of fish passage, operational changes at the dams and keeping predators such as Caspian terns at bay.

The most important strategy of the plan, however, has been habitat restoration since 2000 and officials cite scientific evidence that show the survival of the fishes is directly associated with the quality of their habitat.

Those who oppose the federal plan in court, however, said that restoring the habitat is not enough and urged for the breaching of the dams and spilling more water over the dams. 

"Good habitat is beneficial, but the elephant in the room is the impact of the dams," said Todd True, the lawyer representing the  environmental groups in the case. "Let's address it and not get distracted by the idea that we're spending millions of dollars on habitat so we must be doing something right."