Funny same thing with Ogopogo here in BC. The pictures always turn out fuzzy and with no way of determining distance. Odd that, eh?
I've actually seen the ogopogo though, several times in fact.
Okanogan lake is somewhat like Loch Ness in configuration. Long and thin. This seems to allow the lake to have a silvery sheen at times. When it is moderatly smooth.
Perhaps the parallel, not too far apart shores (a few kms compared to 10's of kms of length) allows for the formation of standing waves more easily. In addtion, the steepish sides allow for vantage points above and looking down on the lake. This gives the sky reflecting silver blue surface of the lake (like mercury). Then when a standing wave forms you get black 'humps'. Often 3 in a row and they will sit there for many minutes at a time. They are exactly what is frequently described in ogopogo sightings.