Not much going on over there this time of year. Wenatchee and Icicle are closed (Wenatchee might be open for whitefish). You might be able to ice fish on Fish Lake north of Leavenworth. If you're into fly fishing, Rocky Ford Creek north of Ephrata can be good in winter, but that's more than an hour away from Leavenworth. I suggest making regular stops at Gustav's to sample their selection of fine ales.