Gehlen (19-10) jumped out to a 10-2 lead in the first set behind five consecutive ace serves off of defenders by Shannon Smith. River Valley (4-30) called a timeout, but Smith continued with another serve after play resumed.
Gehlen pulled ahead by 10 points when Katelin Langel made a diving dig and Baily Wiltgen won the point for Gehlen with a kill. A Wiltgen ace later in the game would give Gehlen a 23-9 edge.
The Jays would finish off the set several points later at 25-11.
"Right off the bat we looked a little rusty, but it has been about 11 or 12 days since we've played," said Gehlen head coach Mike Meyer. "I think it was good that we had a rather large quadrangular-type scrimmage last Thursday, but we were just a little bit rusty.
"I thought from that point on we played pretty well."
Smith nearly served out the rest of the set. The senior finished the match 29-for-30 serving with 10 aces, pacing Gehlen to a season-high 22 aces.
River Valley finally won another point when a shot deflected off of Gehlen blockers to make the score 24-4. River Valley won the next three points, but missed a shot to close out the set at 25-7.
"Our ball control was so much better, we served really well and we didn't give them many opportunities to hit. When we did, for the most part we were pretty successful," Meyer said.
The early part of the third set was much closer. River Valley gained some momentum by winning one of the longer rallies of the match to trail by just three points at 8-5.
The visitors trailed by just two points twice in the early going. Gehlen led just 9-7 before winning seven of the next eight points and forcing another timeout by River Valley.
Abby Freking finished with 24 assists, as well as four aces on 12-for-14 serving. Wiltgen was 10-for-15 serving with five aces.
Smith was 9-for-11 passing. Wiltgen was 6-for-6 passing.
Langel led in digs with six. Smith and Emily Holtgrewe each made four digs.
Wiltgen was the team-leader in kills with 10. Langel hit eight kills. Alison Schnepf and Morgan Whitehead finished the match with seven and five kills, respectively.
"Overall, it was a good opening round," Meyer said. "We look forward to getting to practice and maybe tweaking a few things and step it up another notch each time we advance in the tournament."
Gehlen will go to Akron on Friday to face Remsen-Union (14-8).