Thompson Lake covers 4,426 square acres and has a maximal depth of 120 feet. There is annual stocking of landlocked salmon by the Maine Department of Inland Fisheries and Wildlife, and the other populations are self-sustaining. Presently there is enough dissolved oxygen and water quality to support these fisheries, even during the warm weeks of summer. The deep drop offs within the lake are ideal for salmon and togue. The rocky shorelines offer shelter for small mouth bass, and the shallower areas at the northern and southern ends of the lake contain stable populations of largemouth bass.

The season starts with ice fishing. Ice typically forms on the lake in January, but this can vary significantly. Hard water anglers should always test the thickness of the ice before they venture out to the deeper parts of the lake. Drill or auger a test hole close to shore to test the thickness of the ice before heading out to the deeper areas. Avoid the inlets and outlets and exposed rocks where moving water will create thinner ice. Always let someone know where you are fishing and when you expect to return.
The primary fisheries for ice fishing are togue, bass, pickerel, and cusk (barbot). Keep in mind that salmon are presently off limits, they should not be removed from the water and must be immediately released if hooked. There is also a restriction of 2 traps per fishing license; except for cusk fishing after sunset, when up to 5 traps are allowed. Togue will generally cruise the bottom parts of the lake, fishers do best with jigging but if you prefer more relaxed fishing, use a trap to drop some bait down close to bottom and “chill”. Bass and pickerel will be in the shallower parts of the lake.

Ice out occurs in late March to mid-April and offers some of the best open water fishing for salmon. The smelt run comes early, and the salmon are after them. The temperature of the water column is relatively uniform, and as the surface water is moved by winds the lake will “mix”, thereby circulating oxygen and nutrients. Salmon can be found close to the surface throughout the day. Fishing is typically done by trolling; about as slow as you can go, along the coves that feed into the spawning streams for smelt, and along the rocky shores. It is best to refer to a lake chart, there are many glacial rocky remnants ready to ding a hull or bend a prop.

As the smelt run tails off, the salmon and togue are found in the ledges off shorelines and around the islands in the deeper parts of the lake. Around this time the water temperature begins to stratify, and the fish will seek the deeper water. In the summer the togue will be found at 60 plus feet and salmon fishing can still be good at about 20-30 feet, and closer to the surface at dawn and dusk.

Thompson Lake has excellent small mouth bass fishing in the state and often hosts tournaments. The state record for a small mouth bass was set on Thompson Lake in the 1970’s! The fishing is especially good in early June, when the male bass are guarding their redds and pouncing on anything that would threaten the eggs. They can be found anywhere along the rocky shorelines. Females can be found in the deeper waters offshore, resting from the spawn. Later, as the water warms the fish will head for deeper water but can still found in the shallow areas, especially early and late in the day around rocks and ledges.
Largemouth bass in the 5-6 lbs. class are found in shallow and weedy areas at the northern and southern tips of the lake and at theHeath, which is across the causeway in Casco. Fishing can be done from the shore or a boat. It is important to note that the Heath does not allow motorized boats, and there are colonies of milfoil in this area. Access to the lake can be gained through four public boat launches. The Thompson Lake Marina in Casco has a launch with a small fee. The Robinson Marina near the dam in Oxford also has a small fee. The Pismo Beach launch is available to Oxford town residents only. There is a concrete ramp launch at the “Landing” off Rt 121 in Oxford which is open to the public. There is limited parking, however.

When exiting Thompson Lake, it is extremely critical that you thoroughly inspect and completely drain your watercraft to avoid any cross contamination. On most summer weekends there will be a Courtesy Boat Inspector at the launches to assist boaters in ensuring boats and props are clean upon entering the lake. These inspectors are provided by TLEA to prevent the migration of invasive species to and from Thompson Lake.Importantly, TLEA has spent many years and an abundance of resources on milfoil removal from the shallow parts of the lake, especially around the Pine Point and Otisfield Cove area. If you see any remnant milfoil colonies, be sure not to run your propeller anywhere near them. Fragmentation and migration of these plants can quickly cause milfoil overgrowth throughout the lake, and if left unattended it can spread to other lakes. The Heath has a significant population of milfoil, so any watercraft leaving this part of the lake needs to be carefully inspected and drained to ensure that milfoil fragments are not introduced to other lakes.

Whether bundled up and trolling at ice out, or enjoying a warm sunset and casting for bass in the coves, Thompson Lake offers some of the most productive and enjoyable fishing in the state. The scenic views and high water quality provide a strong sense of satisfaction, even if the fish do not cooperate. Always remember to check the fishing regulations before you head out, and please practice responsible boater safety. While enjoying your time fishing on Thompson Lake, please be respectful of the fishery and be mindful of what TLEA and the Maine Department of Inland Fisheries and Wildlife have done to protect this beautiful resource.