The previous post from May 2007 on Loch Lomond describes it nicely.
One of my favorite day paddles.
Used to be. Sadly.
With the threat of the zebra mussel, you can't bring your boat to paddle there any more. Private boat launching is restricted to boats that are stored at Loch Lomond for the season ($200 annual storage fee + $25 inspection/decontamination fee).
There are some paddle boats and boats for fishermen, but that's it.