I grew up in Shavertown, PA (about 7 miles from Harvey's Lake) and dived the lake on a regular basis back in the 70's. The Harvey's Lake Scuba School and owner Tommy O'Brian are long, long gone. Tommy was quite the character. Kind of marched to the beat of a different drummer when it came to diver training. He wasn't a member of any training agency. He would train divers by using the methods he learned when he was a merchant marine and would issue his own diving certificate. I doubt it would be accepted by anyone else. Many of the local divers did get their first experience by taking one of Tommy's one day intro courses. During the summer months Tommy would charge divers to dive from his property ($5.00 or $10.00 or so if my memory is correct). You could bring a picnic lunch and stay the entire day. He even sunk two or three small boats in about 15ft of water to give divers something to look at. Tommy also would charter a large pontoon boat that he had and take divers to different locations on the lake. But that was a long, long time ago. Tommy was a good friend of many of the local divers in the area (which weren't very many at the time) and he is saddly missed.
Currently there are two dive shops that service the area. Inland Water Sports is located in luzerne (sorry no telephone #) and Scuba America on Gardner Ave in Dunmore (1-570-342-1480)
Except for the State boat launch, Harvey's has pretty much turned into a private lake. Unless you had your own boat, you would have to let someone allow you to cross their property to get to the water. Good luck with that ever happening.
During the 80's, Harvey's use to suffer from large blooms of algae during the summer months. The lake would actually turn a light green. I'm not sure if this is under control. When I use to dive the lake, visibility in the 10-15 ft. range was common. Visibility steadily decreased over the years. I have a depth map of the lake. The deepest point (110 ft.) is located straight out from the old Hanson's Amusement park (which is also long, long gone).