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Oswego Lake dam nears finish line

New gates are going up and that's good news
by: VERN UYETAKE Tuesday was a big day at Oswego Lake Dam as the gates were installed. Thanks to the new dam, the danger of flooding, as occurred in 1996, will be greatly decreased.

The reconstruction of Oswego Lake Dam is a prime example of a great plan coming together.

This week's installation of the dam gates is the final stage of the Oswego Lake Dam Spillway Modification Project, and the danger of flooding in Lake Oswego will be significantly decreased.

Also decreasing will be the flood insurance rates paid by homeowners around the lake.

'The dam will now allow much more water out much quicker,' said David Donaldson, assistant city manager for the city of Lake Oswego and director of emergency management. 'The whole dam structure is being modernized.'

Memories of the great flood of 1996 make this great news for many Lake Oswegans. That year is when the dam could not control the massive amount of water flooding out of the Tualatin River, and water came pouring down State Street and down into the Foothills area.

Thanks to the reconstructed dam, that exciting time will probably not be revisited.

Teaming up for the dam project were the Lake Oswego Corporation and the city of Lake Oswego. FEMA provided a grant of $950,000, while Lake Corp spent over $200,000 for engineering and design.

The timing for the effort was right, too, thanks to the Lake Oswego Interceptor Sewer project.

'It was an opportune time,' Donaldson said. 'We couldn't do it when the lake was up. Now it's going to be rising 1½ feet a week.'

The dam project began with the removal of huge concrete blocks. After drilling, new concrete was poured in and the systems were installed. Metal panels will control water flow.

The most interesting feature of the new dam is the inflatable air bladders, which will be installed by Obermeyer Hydro. Controlling the air pressure in the bladders will allow the gates to be adjusted at an extremely accurate level.

'The air bladder is the real key,' Donaldson said. 'It will regulate the up and down movements of the gates.'

Just one objective remains: Seeing if the new system works. Donaldson said the testing would begin as soon as the lake refills to a suitable level.

As for flood insurance, Donaldson said, 'I'm not yet sure how soon the rating may change. It could take a year.'

Donaldson said the dam project has gone extremely well, and he had high praise for Advanced American (the construction company), Lake Corps manager Jeff Ward, city engineer Erica Rooney, and Dale Richwine of Richwine Environmental.