Lasalle Park is your closest launch and is free with a great ramp and usually adequate parking while only adding a few minutes to your boat ride. On calmer days a run to the blue zone can easily result in plenty of salmon and rainbows hitting the net. Not sure what depths people target at this time of year though as I typically fish Lake O in the spring when the trout and salmon are closer to shore.
I suppose the salmon will be starting to stage near river mouths any time now and towards the end of the month and into September you can troll near river mouths for great action close to shore.
Definitely hit up Spoonpullers for reports, rigging and info.