In the spring of 2001, the Illinois High School Association received a request from the athletic directors at Crystal Lake Central, Cary-Grove and Crystal Lake South.
The three wanted to create a joint girls golf program due to low numbers and interest at each school. Without the agreement, the athletic directors feared they wouldn't be able to field individual teams.
The request was approved on May 25 of that year and the first season with the three schools, competing together as the Crystal Lake Central co-op, began during the 2001-02 season.
"The goal is always the same," Central athletic director Jeff Aldridge said, "to provide opportunities for kids."
Since its inception during the 2001 fall season, the team has gone a remarkable 132-24. Each of the 13 seasons as a co-op has ended with a winning record and Friday will mark the Tigers' third time at the state tournament in the past four years.
On Monday, the Tigers won the Class AA Rockford Guilford Sectional at Ingersoll by four strokes to advance to Friday and Saturday's state meet at Hickory Point Golf Club in Decatur.
Coach Kathy Speaker has heard talk from parents, coaches and players who want to diminish their accomplishments because of the co-op between three of the area's largest schools, which have a combined enrollment of 5,271.
By comparison, only one school in the state (Berwyn-Cicero in Morton) has a higher enrollment at 8,158. The second-highest is Waukegon (4,375).
"They always say we're good because we're a co-op," Speaker said. "That irritates me. "We're good because every one of my girls have shot those scores that other girls are shooting.
"My girls made a commitment to the whole thing and they have worked their tails off getting out there every day."
IHSA rules say that any public, or private school with an enrollment under 200, can co-op with another school out of necessity. Schools larger than that must go through an application process with the IHSA.
The schools must indicate which school will be the host and the reason for joining, which is typically is low numbers. That can be proven by a survey of student interest.
After the initial approval, the schools must simply submit a renewal request every two years.
Sometimes school form co-ops due to lack of facilities. When Woodstock North was established in 2008, the school had a plan to co-op with Woodstock in sports such as swimming, golf and bowling and even track during the 2008-09 season in order to get off the ground. The track teams have since split.
"It just makes sense for us," Thunder athletic director Nicholas Kearfott said. "Having a pool makes it an easy decision but we're always looking to see if we can sustain a program by ourselves."
Athletic directors keep an eye on interest levels in programs and take that into account when applying for a co-op and a renewal, though several factors go into the decision.
"If any one school had numbers, you would consider branching off," Aldridge said. "But you have to pay a coach, have facilities and maybe you have enough kids this year but not the next.
"You look for a trend and even if you might have numbers, does your school leaving [the co-op] cripple the other schools?"
Every four years, the state mandates that schools take a student interest survey, which is supposed to help school officials determine interest level.
All three athletic directors from the schools involved say they are comfortable in the situation and feel it is best to stay together. Though, in light of the Tigers' sectional win Monday, some look at co-ops as an opportunity for schools to join to create a powerhouse.
"I think they're a good thing; the original nature of the co-op team," IHSA associate executive director Kurt Gibson said. "They really do need to exist and, initially, they were created to ideally help smaller schools who have a tough time fielding a team to join up with the next town.
"But over time we've seen that idea sort of lose its way a bit and there might be some situations where we're seeing some co-ops in some sports and people wonder why those folks with higher enrollments aren't able to field their own teams."
According to the IHSA website, Central has an enrollment of 1,571, South has 1,854 students and Cary-Grove has 1,846. They are three of the area's largest schools.
"It's definitely a little bit harder," Huntley coach Ann Christiansen said of competing against the Tigers, "but those girls work hard and they deserve every bit of their success."
Prairie Ridge, the one District 155 school not part of the co-op, is similarly sized and began the season with just five girls golfers, an all-time low. But coach Patti Hie said she never thought about forming a co-op due to previous seasons with high numbers.
The Wolves went to state last season and finished one spot ahead of the Tigers by three strokes.
The co-op schools say that interest for each has remained steadily low, averaging around 15 total. Seven regularly compete at the varsity level, with Lexi Harkins representing Central, Cary-Grove sending Larisa Luloff, Emily Jean and Lauren Kalamaras and South supplying Bailey Bostler, Brianna DiGrazia and Alex Siavelis.
Success in sports, especially golf, usually hinges on a dominant player. Harkins, one of the state's top golfers since she placed fourth at the meet as a freshman in 2010, has been a large reason that the Tigers have been so good.
She led the team to a state berth this season after shooting a 75 at Monday's sectional. The co-op made it to state last season without her but, take away her score on Monday and the Tigers would have missed state as a team.
"There is no data correlating playoff [appearances] with co-op teams that come across my desk," said Gibson, who is in his 12th year at his position with the IHSA. "There are some instances, but usually it's not overly beneficial."