The Lafayette Parish School System could lose up to $17 million over the next two school years as the three charter schools in the parish expand and a new charter school opens in August, school officials say.

The potential flight of funds would come from the loss of students whose parents opt to enroll them in the charter schools.

The loss of per student funding for the district contributed to a $20 million shortfall last year as the School Board prepared to balance the budget for the current school year. The charter schools weren’t the sole reason for the shortfall. School officials also pointed to rising costs associated with retirement and benefits and other state mandates.

But the charter schools appear to be the main target.

“The imposition of state-approved charter schools in Lafayette Parish and the resulting diversion of local funds to those schools pose a significant financial challenge to the Lafayette Parish School System. Reductions in expenditures will be needed to balance the budget in future fiscal years,” Finance Director Matt Dugas and Chief Financial Officer Billy Guidry wrote in a letter submitted as part of an audit of the school system for the 2013-14 fiscal year that ended June 30.

The School Board rejected the initial applications for the charter schools in 2013. However, the schools received approval from the Louisiana Board of Elementary and Secondary Education. Two different charter school management companies opened schools in the parish in August. Charter Schools USA, based in Florida, opened two schools, while National Heritage Academies, with headquarters in Michigan, opened one and will open another in August. The NHA campus enrolled fewer than 500 students, while Charter Schools USA’s two schools enrolled a total of about 1,200 students.

Guidry said it’s been difficult to pinpoint the exact financial impact on the public school system because he is awaiting official enrollment counts and a breakdown of how many students enrolled in the charter schools were previously Lafayette Parish school students. The charter schools are able to enroll students from outside of Lafayette Parish.

The impact of four charter schools open in the parish in the upcoming 2015-16 school year was estimated at $9 million and at $8 million the following school year, Guidry said. Charter Schools USA plans to open a high school in the parish by 2017. Its location is undecided, but will likely be in the southern part of the parish where population has ballooned.

The charter schools also are eligible to receive a portion of local tax revenues for each Lafayette Parish student enrolled on their campuses. This school year that translates to $2,105 per student from local sales tax collections, Guidry told area legislators at an event organized by the school officials last month. Guidry said legislation could provide some financial relief because the taxes are dedicated for specific purposes, so the school system has to find other funds to make up for dedicated taxes that are redirected to the charter schools.

The school system’s latest audit — conducted by Kolder, Champagne, Slaven & Company — also found that the district needs improved controls over sales tax collections and money collected at schools through fundraisers and other activities. The school system responded that it routinely audits school accounts and improved accountability measures are in place. Also, the School Board recently approved a new position of an assistant sales tax director which will help provide greater accountability for sales tax collections.

Auditors also questioned some activities that had been outlined in the 2012-13 audit and that also were investigated by the School Board’s attorney as part of a process that led to then-superintendent Pat Cooper’s termination in November. Those issues included the hiring of some principals at different pay than others; Cooper attending a BESE meeting in fall 2013 to speak in support of charter schools despite the School Board’s opposition to the schools’ applications; and Cooper’s hiring of an attorney without board approval.

Follow Marsha Sills on Twitter, @Marsha_Sills.