The Thursday letter, “Objections to dam misleading” is itself misleading. Describing the dam as an inflatable floating weir makes it sound like some oversized pool toy. In fact, plans call for a 7-foot high, 132-foot long steel crest gate attached to a 260-foot concrete foundation. Inflating rubber bladders between the two raises the crest gate to divert the river through a ½ mile tunnel into the turbines. Nothing will be floating.
Spawning salmon have had access to the habitat above Sunset Falls ever since the existing trap-and-haul facility was opened in 1958. SnoPUD has resisted describing planned improvements to the facility. In 2009, a record 124,248 fish were hauled above the falls. Fish numbers in most years were much less, averaging only 25,604 over 1958-2011, well below maximum capacity. The major factor determining the number of fish trapped and hauled is likely the number of fish successfully returning from the ocean.
Downstream migrating fish will be screened from the turbines, but must then survive two waterfalls with little water to cushion their fall, because up to 90 percent of the water will be diverted through the turbines. We don’t know what the resulting fish loss from injury and abrasion will be, but that loss will result in an equal loss of fish returning in later years. Even a few percent loss of fish is unlikely to be compensated by improving efficiency in the trap-and-haul. which usually uses less than 25 percent of present capacity.
I agree that energy conservation is the best solution.
Petrie Rainey, MD, PhD