MyFishFinder.com Just like iceshanty but warmer
Browns Lake has been red hot lately. Lots of big rainbows that love to bite And just as missoulafish stated, there are HUGE perch in Salmon Lake, along with the chance of catching big pike and trout. It's definitely worth the extra drive. Another idea is the Causeway or Regulating Reservoir in Helena. They are both fishing well so far this year. Canyon Ferry is a good option, but is hasn't quite heated up yet this year.
I fished Brown's on Friday last week and the bite was anything but red hot. Managed a sucker and a 12" rainbow in three hours between three of us. Upsata was a bust that day as well. I have heard Harper's is fishing well with some gagger rainbows being drug out of there. Good luck!