7. Debt:

Long-term debt consists of first mortgage notes payable to the United States of America acting through the Federal Financing Bank (FFB) and guaranteed by the Rural Utilities Service or the U.S. Department of Energy, first mortgage bonds payable (FMBs), first mortgage notes issued in conjunction with the sale by public authorities of pollution control revenue bonds (PCBs) and first mortgage notes payable to CoBank and CFC. Substantially all of our owned tangible and certain of our intangible assets are pledged under our first mortgage indenture as collateral for the Federal Financing Bank notes, the first mortgage bonds, the first mortgage notes issued in conjunction with the sale of pollution control revenue bonds, and the CoBank and CFC first mortgage notes.

Maturities for long-term debt and capital lease obligations through 2021 are as follows:


		(dollars in thousands)
		2017		2018		2019		2020		2021

FFB	$	183,259	$	151,297	$	156,376	$	171,441	$	176,620
FMBs		1,010		1,010		351,010		1,010		1,010
PCBs(1)		122,620		56,028		37,352		188,226		36,000
CFC		937		984		1,035		391		–
CoBank		2,600		–		–		–		–

		310,426		209,319		545,773		361,068		213,630
Capital Leases		6,435		4,905		5,462		6,082		6,772

Total	$	316,861	$	214,224	$	551,235	$	367,150	$	220,402


(1)	In addition to regularly scheduled principal payments on the bonds, this includes amounts that would be due if the standby letters of credit supporting the Series 2009 and Series 2010 bonds were drawn upon and became payable in accordance with their terms, such as would occur if the credit facility the letters of credit were issued under was not renewed or extended at its expiration date. These amounts equal $56 million in 2018, $37 million in 2019 and $152 million in 2020. We anticipate extending these credit facilities before their expiration. The nominal maturities of the Series 2009 and Series 2010 pollution control bonds range from 2030 through 2038.

The weighted average interest rate on our long-term debt at December 31, 2016 and 2015 was 4.34% and 4.45%, respectively.

Long-term debt outstanding and the associated unamortized debt issuance costs and debt discounts at December 31, 2016 and 2015 are as follows:


	2016				2015
		Principal		Unamortized Debt Issuance Costs and Debt Discounts		Principal		Unamortized Debt Issuance Costs and Debt Discounts

		(dollars in thousands)
FFB	$	4,259,723	$	55,754	$	3,777,540	$	56,851
FMBs		3,058,083		36,717		2,809,093		32,002
PCBs		980,770		8,789		980,770		9,135
CFC		3,347		–		4,238		–
CoBank		2,600		–		3,386		–

	$	8,304,523	$	101,260	$	7,575,027	$	97,988

We use the effective interest rate method to amortize debt issuance costs and debt discounts as well as the straight-line method when the results approximate those of the effective interest rate method. Unamortized debt issuance costs and debt discounts are being amortized to expense over the life of the respective debt issues.


a)	Department of Energy Loan Guarantee:

Pursuant to the loan guarantee program established under Title XVII of the Energy Policy Act of 2005 (the "Title XVII Loan Guarantee Program"), we and the U.S. Department of Energy, acting by and through the Secretary of Energy, entered into a Loan Guarantee Agreement on February 20, 2014 pursuant to which the Department of Energy agreed to guarantee our obligations under the Note Purchase Agreement dated as of February 20, 2014 (the "Note Purchase Agreement"), among us, the FFB and the Department of Energy and two future advance promissory notes, each dated February 20, 2014, made by us to the FFB (the "FFB Notes" and together with the Note Purchase Agreement, the "FFB Credit Facility Documents"). The FFB Credit Facility Documents provide for a multi-advance term loan facility (the "Facility"), under which we may make long-term loan borrowings through the FFB.

Proceeds of advances made under the Facility will be used to reimburse us for a portion of certain costs of construction relating to Vogtle Units No. 3 and No. 4 that are eligible for financing under the Title XVII Loan Guarantee Program. Aggregate borrowings under the Facility may not exceed $3,057,069,461, of which $335,471,604 is designated for capitalized interest.

Under the Loan Guarantee Agreement, we are obligated to reimburse the Department of Energy in the event the Department of Energy is required to make any payments to the FFB under the guarantee. Our payment obligations to FFB under the FFB Notes and reimbursement obligations to the Department of Energy under its guarantee are secured equally and ratably with all of our other notes and obligations issued under our first mortgage indenture. The final maturity date for each advance is February 20, 2044. Interest is payable quarterly in arrears and principal payments will begin on February 20, 2020. Under both FFB Notes, the interest rates during the applicable interest rate periods will equal the current average yield on U.S. Treasuries of comparable maturity at the beginning of the interest rate period, plus a spread equal to 0.375%.

During 2016, we received advances under the Facility totaling $450,000,000. At December 31, 2016, aggregate DOE-guaranteed borrowings totaled $1,678,442,000, including capitalized interest. Advances may be requested under the Facility on a quarterly basis through December 31, 2020. Future advances are subject to satisfaction of customary conditions, including certification of compliance with the requirements of the Title XVII Loan Guarantee Program, accuracy of project-related representations and warranties, delivery of updated project-related information, our continued ownership of our interest in Vogtle Units No. 3 and No. 4 free and clear of any liens except those permitted under the Loan Guarantee Agreement, evidence of compliance with the prevailing wage requirements of the Davis-Bacon Act, as amended, and certification from the Department of Energy's consulting engineer that proceeds of the advance are used to reimburse eligible project costs. The failure by the Contractor to perform its obligations under the EPC Agreement could affect our ability to satisfy the conditions required to receive future advances.

Under the Loan Guarantee Agreement, we are subject to customary borrower affirmative and negative covenants and events of default. In addition, we are subject to project-related reporting requirements and other project-specific covenants and events of default.

If certain events occur, the Department of Energy may, at its option, (i) elect to suspend or terminate the FFB's commitment to make further advances under the Facility, and may later revoke any such suspension, or (ii) require us to repay the outstanding principal amount of all borrowings under the Facility over a period of five years, with level principal amortization. These events include (i) cessation of the construction of Vogtle Units No. 3 and No. 4 for twelve consecutive months, (ii) termination of the EPC Agreement under certain circumstances, (iii) loss of or failure to receive necessary regulatory approvals under certain circumstances, (iv) loss of access to intellectual property rights necessary to construct or operate Vogtle Units No. 3 and No. 4 under certain circumstances, (v) our failure to fund our share of operation and maintenance expenses for Vogtle Units No. 3 and No. 4 for twelve consecutive months, (vi) change of control of Oglethorpe and (vii) certain events of loss or condemnation. If we receive proceeds from an event of condemnation relating to Vogtle Units No. 3 and No. 4, such proceeds must be applied to immediately prepay outstanding borrowings under the Facility. We may also voluntarily prepay outstanding borrowings under the Facility. Under the FFB Credit Facility Documents, any prepayment will be subject to a make-whole premium or discount, as applicable.

Upon notice to the Department of Energy from the Co-owners of their intent to terminate the EPC Agreement for convenience, the Department of Energy may elect to continue construction of Vogtle Units No. 3 and No. 4. In such an event, unless we elect to join the Department of Energy in continuing construction, the Department of Energy will have the right, subject to certain conditions including obtaining necessary NRC approvals, to assume our rights and obligations under the principal agreements relating to Vogtle Units No. 3 and No. 4 and to acquire all or a portion of our ownership interest in Vogtle Units No. 3 and No. 4.


b)	Rural Utilities Service Guaranteed Loans:

During 2016, we received advances on Rural Utilities Service-guaranteed Federal Financing Bank loans totaling $94,460,000 for long-term financing of general and environmental improvements at existing plants.

In January 2017, we received an additional $4,517,000 in advances on Rural Utilities Service-guaranteed Federal Financing Bank loans for long-term financing of general and environmental improvements at existing plants.


c)	Pollution Control Revenue Bonds:

In January 2017, we refinanced $122,600,000 of variable rate pollution control revenue bonds with original maturity dates ranging from 2020 through 2040, through the issuance of commercial paper. The bonds were classified as current debt at December 31, 2016.


d)	Credit Facilities:

As of December 31, 2016, we had a total of $1,610,000,000 of committed credit arrangements comprised of four separate facilities with maturity dates that range from October 2018 to March 2020. These credit facilities are for general working capital purposes, issuing letters of credit and backing up outstanding commercial paper. Under our unsecured committed lines of credit that we had in place at December 31, 2016, we had the ability to issue letters of credit totaling $760,000,000 in the aggregate, of which $509,000,000 remained available. At December 31, 2016, we had 1) $251,000,000 under these lines of credit in the form of issued letters of credit supporting variable rate demand bonds and collateral postings to third parties, and 2) $102,000,000 dedicated under one of these lines of credit to support a like amount of commercial paper that was outstanding.

The weighted average interest rate on short-term borrowings at December 31, 2016 and December 31, 2015 was 0.93% and 0.43%, respectively.