Surprizes me to see no one from Wisconsin recommends the Horicon Marsh studies on increasing muskrat population densities by mechanical excavation designs. They (managers) tried about every thought proposed and after a lot of trial and error, came up with designs that increased muskrat numbers in that vast "sea" of cattails to where they could actually pay for the construction costs in 2-3 year's harvest (depending on the fur price). Good return on your money. The key to increasing any wildlife numbers (populations) is having an EXPERIENCED person evaluate what habitat you currently have (Food, Cover, Water) and then increase the QUALITY, not necessarily just expand the area. Deer leases do it and have for years. Unfortunately there are only a few, if any biologists or individual river rat types, who can do that for muskrats now days. Too much water is about as restrictive as too little. Use fish production in a lake or pond as an example: it is recommended that you would need 75% of your surface water as shallow nursery areas and 20-25% as a deep water survival (summer & winter) area for warm water species (bass, bluegills etc.). Too much deep water and you only have fewer "cribs and food for the "babies". Savvy? The same ideas/goal (with different percentages) exists for muskrats. So you need to gather as much of the previous info as possible, evaluate (have someone who is qualified) the existing condition(s), and determine if you can construct/build the landscape to mirror previous proven methods, if you'er interested in increasing muskrat densities. You may be already there or not even close but w/o a Recon of the existing Food, Cover and H2O you are shooting in the dark. ............................ my experience ............. the mike