Financial documents show that the pension fund for Chicago Public Schools teachers is an additional $1 billion in debt due to less aggressive investment return estimates.

Consultants for the Chicago Teachers’ Pension Fund now say the system is about $11 billion in debt. The documents show that the extra debt will make it even more difficult to comply with state law that requires the fund be 90 percent funded by 2059.

Chicago Public School CEO Janice Jackson says the district will continue to meet its obligations but also will continue to lobby for more funding to support schools.