An ideal would be to lower the lake a few feet and look for dens, but probably not happening. Are there cat tails? Are they bank rats or hut builders? I play at a golf course regularly that has several inter-connected ponds. It borders a huge lake, (talking 96 square miles), that has abundant rats. The banks of those ponds have considerable muskrat damage, but even in the un-likely event I could wipe them out, they would re-populate in one spring. And even though I see them frequently, and see the water fluctuate a lot, i couldn't begin to guess how many there are, as the course rats don't build huts.
A large marsh I trap has hut builders, and after trapping it for a few years and spending time there year-round, I have a decent idea how many rats might be there, give or take a couple hundred.
I have not seen the lake yet and its probably a few acres at most. We dont have a lot of lakes or large ones around here. To many fishers and cracks in the rock and why i have sink holes
It hit and miss when people dig a lake on if it will hold water or they end up with dry lake or maybe mostly dry with shallow mosquito pit on one end.
The one time I targeted them the lake didn't have cat tails and I just set the tunnels/runs they made going into the dam. So if the lake is more wild I have no clue how to effectively thin them out or trap them like in a marsh I never spent any time learning about them. Mostly I have targeted coon, possum, (nest preditors) ground hogs and coyotes, with the now and then beaver for friends or to get a foot in the door to trap other critters, and hunting ot fishing axcess. And of course I have picked up the incident mink( never targeted) fox, skunk, bobcat and otter. So I have a lot to learn to be consistent with several species vs just catching a few now and then.
If I have to guess this lake will be clean mayey some treas around it and not a lot of cattails but I could be wrong. And wanted to be prepared when I show up. I guess I will buy some more 110s and take some 1.5s to set anything that look like a trail on land and run it on a drowning set. And any runs unde water and bank holes will get a 110. Hopefully that will do the trick. I thought I read something about lure and or bait set for them. I may run through the archives if trail sets dont get it done.