Union Reservoir satellite view

Union Reservoir Fishing Report

|Union Reservoir, CO
76% confidence 62°F Clear

The cooling trend makes fish less willing to chase, so contact baits and precise casts will out-fish search baits here.

comprehensive plan Analyze Past Water Temperature Analyze Species Behavior Analyze Solunar Timing Analyze Hourly Conditions Analyze Weather Conditions Lure Matrix Wind Clarity
Yellow perchBlack crappieChannel catfishBrown troutRainbow troutLargemouth bassSmallmouth bassBluegill

THE CALL
Fish the north-end thermal edge and the northeast developed point with a white/chartreuse chatterbait or swim jig from 7:00–9:00 AM MDT, then shift to the midday solunar window (12:18–2:48 PM) on the same transition zones. This is a pre-spawn/spawn pattern on cooling 62°F water with stained clarity and a sharp temperature break that concentrates active bass.

WHY IT WINS

  • Thermal edge: The May 13 thermal imagery shows a massive 84°F core in the main basin, with a sharp drop to 51–83°F along the western and northern peripheries. Predators patrol that wall, not the hot center.
  • Cooling trend: Water has dropped 11.9°F over recent readings and sits 5.8°F below the seasonal median. Fish are compressing their feeding windows and holding tighter to structure and temperature breaks.
  • Clarity and wind: Stained to moderately murky water (from March clarity imagery) means fish rely on vibration and silhouette. The 5–6 mph north wind today pushes bait and adds oxygen to the north shore, making that thermal edge even more active.
  • Solunar overlap: The early morning window (7–8 AM) scores 85/100 due to light wind, low pressure, and a major solunar period. A second major window hits 12:18–2:48 PM.

START HERE
The Northeast Developed Point – From the center of the lake, head northeast toward the visible structures/buildings on the shoreline. The satellite imagery shows a color transition from light tan (very shallow) to medium green (moderate depth), indicating a ledge or drop-off. This spot sits right on the northern thermal edge where cooler water meets the warm core. Work the length of that transition, especially where the shoreline juts out.

THROW THIS

  • Primary: 3/8–1/2 oz chatterbait or swim jig in white/chartreuse (for stain) or natural shad (if you find a clearer lane). Retrieve steady and moderate – let the blade or skirt do the work. Cast parallel to the thermal edge and let it fall off the ledge.
  • Backup: Texas-rigged creature bait (white or green pumpkin, 3/8 oz weight) – pitch to any visible cover (docks, laydowns, rock) on the shallow flats behind the point. The 62°F water has bass staging near spawning areas, and a slow, precise presentation will pick off neutral fish.

BEST WINDOW
7:00–9:00 AM MDT – Light wind (4–6 mph), low pressure, and a major solunar period align for the highest hourly score (85/100). Fish will be most aggressive on the thermal edge during this low-light, stable-pressure window. If you miss that, the 12:18–2:48 PM major solunar is your second shot – expect a shorter, more intense flurry as the sun peaks.

NEXT MOVE
If the northeast point and thermal edge don’t produce after 45 minutes, slide to the Western Shoreline – the irregular coves and shallow flats shown in satellite imagery. These are prime spawning pockets for largemouth and bluegill. Slow down with the Texas-rig creature bait or a wacky rig (green pumpkin) and methodically work every indentation. The cooling trend makes fish less willing to chase, so contact baits and precise casts will out-fish search baits here.