Bonneville Power Administration(BPA) has postponed its previously planned spillage of water at Columbia river hydro dams by a few weeks. The spillage was to facilitate the downstream migration of juvenile salmon in the river. BPA, a US federal agency, cited the prevailing severe drought in the northwest and concerns over power supplies as the reason for the change.

BPA said that the water saved by not spilling is enough to generate 1000MW. The National Marine and Fisheries Service (NMFS) estimates that halting the spill programme will decrease survival rates by anything from 0-15% on the Columbia river, and by about 0-2% on the Snake river.

Northwest states like Washington depend on hydroelectricity for about 70% of their energy during normal rainfall years. In an independent analysis, the four-state Northwest Power Planning Council has determined that the region will be short of electricity this spring and fall unless steps are taken immediately to both reduce demand and conserve water at the Columbia river dams.

In order to minimise the effect on the fish the NMFS, US Army Corps of Engineers (USACE) and US Bureau of Reclamation are planning to haul thousands more young salmon downstream in trucks and barges this year. The fish will be removed from the river at federal dams in Washington and Oregon and dropped below the Bonneville dam, a distance of 466km.

Officials have expressed concern that the record low rainfall in the region has left the Columbia and Snake rivers shallow, warm and sluggish – unfriendly conditions for migrating juvenile salmon. The Corps, which owns and operates eight federal dams on the lower Columbia and Snake rivers, has been transporting fish in trucks and barges since 1968.