The 32ft-long fibreglass whale was brought to rid Astoria's port of the sea lions after they failed to leave as expected once the weather got warmer.
Officials say the sea lions are putting thousands of jobs in the city at risk.
First attempts to use the fake orca ran into trouble on Thursday, after its motor became flooded.
Officials say they may try again on Friday.
"It really is a sign of how desperate the measures are that we're taking to try and solve this problem," Jim Knight, Port of Astoria Executive Director, said.
"We simply don't have the financial resources to build barriers. We have no choice but to look for very creative and low-cost solutions."
