Quick update to add there are a lot of ants & termites in the area, fish could be keying on those. The lake is quickly warming up and the fish can be found cruising the shallower areas near the shore. Don't forget to check out the shallow areas of the lake. If you spend time observing, you will see them rising to take emerging mayflies and ants. The Mahagonies and Callibaetis are not really coming off in droves as of yet, but it would be a good idea to have some duns in your box in size 14. Zebra Midges, Balanced Damsels and #14 - 16 PTs fished under indicators or on an I-Line are good methods right now.

Pay attention to the special regulations here, especially where you can and can't fish. Barbless hooks, artificial lures, catch and release. Make sure you inquire at the park entrance.

Hot Flies: 
Dry Flies:
Harrop's Last Chance - #16-20, Adams - #14-18, Mayfly Cripple - #18, Last Chance Cripple - Callibaetis or Baetis, Mercer's Missing Link - #14-16, Mercer's Parachute Profile Spinner

Nymphs/Wet Flies:
Zack's Attack Damsel, Burk's Sierra Damsel, Black A.P. - #14-16, Hogan's S&M - Olive #16-18, Beaded Zebra Midge - Black #18-20, Mercer's Gidgets

Streamers & Leeches:
Beaded Micro Bugger - Black, Zonkers - #4, Beaded Micro Buggers - Any