December 6, 1999

Locks to get more fish friendly

By JON SAVELLE
Journal Environmental editor

The Ballard Locks, so pleasing to the 1.5 million people who visit them every year, have been hard on baby salmon. Smolts have been getting mangled in the locks' underwater culverts as powerful currents slam them into barnacle-covered concrete walls.

Studies of fish mortality at the locks have shown these culverts to be the worst enemy of juveniles headed out to sea. But a fix is in the works. Thanks to a collaboration of the city of Seattle, King County, the U.S. Army Corps of Engineers, watershed forums and the Muckleshoot Tribe, work is underway to make the locks a piscatorial pal.

The large lock is getting fish-passage improvements during its annual draining for maintenance. Photos by Jon Savelle

There are two main components of the $2.3 million project, which officially got underway on Friday. The first part has to do with two culverts that direct fresh water from the Ship Canal into the large lock.

These concrete tunnels, each about 14 feet high, work as giant valves.

When lock operators want to raise water in the lock from the level of Puget Sound to that of the Ship Canal, they open gates in the culverts to admit water from the canal. It surges into the culverts at high speed, then enters the lock through ports along the bottom. The incoming water raises the level in the lock, lifting vessels until they are level with the canal. Then the eastern gates of the lock swing open to allow vessels through.

The trouble is, the culverts subject juvenile salmon to tremendous hydraulic forces. And their barnacle-lined walls have been efficient shredders of fish.

Col. Mike Rigsby, district engineer for the Corps, said about 35 percent of the smolts don't make it past the culverts.

To improve the culverts, the Corps is taking three steps. One is to scrape millions of barnacles off of the culvert walls, in hopes that the relatively smooth concrete underneath will prove less abrasive. The second step is to install strobe lights at the entrances to the culverts -- a tactic that has been proven effective in keeping smolts out. And the third step is to slow down the rate at which filling of the lock occurs, so that the power of the water in the culverts is reduced.

If the smolts are kept out of the culverts, of course, they must have some other way to get to salt water. That's the other main component of the project: a series of four flumes will be installed seasonally atop two spillways on the locks dam, providing smolts safe passage over the dam.

Corps Spokeswoman Patricia Graesser said a test flume has been in use for the past four years, and has successfully guided some 500,000 smolts to Puget Sound each spring.

Fish-deterring strobe lights have been installed at the entrances to the lock-filling culverts.

No flumes are in place now. But crews were busy last week removing barnacles and installing strobe lights while the large lock was drained for its annual maintenance. A tour of the site revealed the dimensions of the facilty: the culverts easily accommodated a platoon of reporters, photographers and government officials. Among them were King County Councilmember Larry Phillips, Seattle City Councilmember Margaret Pageler and Muckleshoot fish biologist Eric Warner.

Out in the lock the millions of dying barnacles emitted an aroma of overripe seafood. An assortment of tires -- no doubt lost boat bumpers -- littered the floor. Warner, who has worked on fish passage at the locks for years, said a handgun was the most interesting find on the bottom this year. Other years have turned up equally odd things, including a sunken boat.

"It was a challenge getting that out," he said.

Inside the culverts, walls have been scraped clean of barnacles. The valve gate, shown here as a metal frame, will be used to modulate flows.

But Warner is not so glib about salmon recovery. While he agrees with the elected officials, who said the improvements at the locks should vastly improve smolts' survival rates, Warner cautioned that those improvements by themselves are not enough. In particular, he said, it is crucial that adequate flows of water find their way through the locks so that the improvements will function properly.

"They should not be undermined by increased withdrawals upstream," Warner said. "The (city of Seattle's) Cedar River Habitat Conservation Plan seems to allow increasing water withdrawals by 100 percent."

Apart from that, Warner believes the improved fish passage at the locks should provide a big benefit to the four anadromous fish species that pass through them, especially the threatened Puget Sound chinook.

This phase of the project, to install the strobe lights and remove the barnacles, was to be completed today so that the lock could be refilled. The smolt flumes will be installed by April. Both the strobes and the flumes will be operated from April to July, during the salmon's downstream migration, and the entire effort will be monitored for two years to make sure it is working properly.