Most Boulder Mountain lakes that are closed during the winter will open to fishing on April 19. Check the Utah Fishing Guidebook to see which Boulder Mountain lakes are closed to fishing through the winter (lakes are listed under individual names, not "Boulder Mountain"). Spring is one of the best times to fish on Boulder Mountain as fish wake up from winter sluggishness and feed actively. Access and ice-off starts at the lowest-elevation lakes in mid-April to early May. Lakes under the Boulder Top rim (9,000–10,000 feet) open up between mid-May and early June. The Boulder Top lakes typically aren't accessible until mid-June to early July. Consult the Boulder Mountain entry on the Fish Utah interactive map for fishing techniques and tips.