There is a tree across from the Harrison Hotel, near where the wharf is. It is on the left side of the path overlooking the water and I've tried everything to find out what it is. It is quite large approximately 20 - 30 ft. tall with a sturdy trunk and it has small leaves, oval shaped, which grow on almost a trailing branch. The flowers are spectacular as they are so fragrant and grow almost in a grape-like cluster, they are white, turning cream as they age. It is blooming right now and I'm not sure when it started or ends as we were there on the week-end. I would be ever so grateful if anyone could help.
Robinia pseudoacacia. As far as trees go, 30' is a small tree. Large trees are those over 60' tall. R. pseudoacacia is one of those kinds that grows over 60' tall. For example, one in Walla Walla was 109' tall in 1993.
Although typical wild black locust is not a regular garden center item the gold leaved cultivar 'Frisia', as well as hybrids such as this one have been at local stores in the recent past. http://oregonstate.edu/dept/ldplants/ropurpr.htm