For the purchase of the WTC Systems, the LCRA required compensation for the principal balance of bonds and commercial paper allocated to the Systems, in addition to any defeasance costs to retire those bonds early. Due to the high LCRA defeasance cost estimates, the Agency along with the UDC, negotiated an installment purchase agreement whereby the Agency pays the LCRA for annual interest and principal payments on all bonds that the LCRA had allocated to the WTC Systems, until they become callable. At that point, the Agency issues its own bonds to pay the LCRA the principal due for the bonds plus accrued interest. The first and second installments, totaling approximately $121,000,000 paid to the LCRA were in 2012 and 2013, respectively. The final installment payments were due in 2015 and 2019. The Agency did not pay a premium, above the amount of the debt allocated by the LCRA, to purchase the system assets. The Agency paid the LCRA an estimated total of $165,000,000 for the WTC Systems.