My camp has extensive beaver flooding and as others have pointed out, it can be a real positive or negative. Personally, I like the environment they create, though I wish it was on a slightly smaller scale in my case. Should you let them stay, anticipate awesome wildlife experiences that you'd be hard pressed to encounter without beaver habitat. Plus, I can attest the flooding makes a phenomenal fence and may just provide you with an excellent deterrent to trespassers. On the negative side, in addition to obvious potential for excessive flooding and tree loss, be prepared to surrender that "master of your own domain", thing. At least as it pertains to that specific area. For example, I timbered an area of mature poplar pretty close to the existing pond that regenerated almost over night into young, super thick sapling growth. The deer herd fell in love with it. And because of that, I became real fond of it as well. Unfortunately, a few years later the beaver moved on it and completely devoured it all. 100% gone. Now, that area has become a couple acres of new growth balsam and pine. For my property, that's not necessarily bad, it's just that it was a decision made without my consent. Unsolicited land management so to speak.