Galena scored first in the game, on a pair of Kaitlyn Hawthorne free throws at the 6:46 mark of the first period. The 2-0 edge was Galena's lone lead of the night.
Spanish Springs knotted the game at 2-2 with a pair of Laneesha Terrance free throws 12 seconds later.
Then Holladay took over.
The Cougars' senior shooting guard, who has signed to play at Division II Cal-State Stanislaus for her collegiate career, poured in 18 straight points for the SSHS crew and it led 20-4 at the first period's conclusion.
"Riley just got off to a torrid start," Spanish Springs coach Christine Eckles. "That was pretty impressive. She hit a couple threes, ran the floor and finished in transition and then she got some steals in the back-court that gave her a few layups. Her effort was really phenomenal. That really got us going."
The Cougars were in cruise control from there as the Grizzlies were outmatched and unable to ever mount any kind of comeback.
Spanish Springs did not cool off in the second quarter. The hosts scored 12 of the first 14 points in the period. That spurt was capped on a scoop shot outside the lane by Holladay, making the scoreboard read 32-6 with just over a minute to go before halftime.
The Cougars took a 34-8 advantage into the locker room at the break.
Spanish Springs did not let up. It outscored Galena 16-7 in the third quarter.
A Lyndsey Anderson layup at the third quarter's 2:32 mark pushed the Spanish Springs lead to 50-11. It was the Cougars' biggest lead of the night.
Anderson added 12 points to the local school's winning effort.
"I was pleased that we never had a letdown," Eckles said. "We ran out to a good first quarter, kept it up in the second quarter and then came out of halftime with good intensity too."
Galena outscored Spanish Springs 14-12 in a fourth quarter where the Cougars' reserves saw the bulk of the playing time.
Spanish Springs shot a solid 28-of-62 (45 percent) from the field while Galena was only 12-of-40 (30 percent). The Cougars forced Galena into 31 turnovers and snared 16 steals.
Spanish Springs (17-5, 8-3) is in action again Friday when it hosts league-leading Reno at 5:15 p.m.
"Reno is very good," Eckles said. "They've proven that all season. They got us pretty good the first time around, but we'll come out and compete. If you're a competitor, games like this are why you play."