6. DEBT

Short-Term Debt

At June 30, 2014, our short-term debt consisted of commercial paper notes payable with a maximum maturity of 39 days, an average maturity of 28 days, and an outstanding balance of $74.2 million. The carrying cost of our commercial paper approximates fair value using Level 2 inputs due to the short-term nature of the notes. See Note 2 in our 2013 Form 10-K for a description of the fair value hierarchy.

Current Maturities of Long-Term Debt

The utility has long-term debt due within the next 12 months totaling $100 million, consisting of $50 million of first rate mortgage bonds (FMB) with a coupon rate of 3.95% and maturity in July 2014, $10 million of FMBs with a coupon rate of 8.26% and maturity in September 2014, and $40 million of FMBs with a coupon rate of 4.70% and maturity in June 2015.

Long-Term Debt

Our utility segment has long-term debt, including current maturities of $701.7 million, consisting of FMBs at June 30, 2014, with maturity dates ranging from 2014 through 2042, interest rates ranging from 3.176% to 9.05%, and a weighted-average coupon rate of 5.55%.

At June 30, 2014, our gas storage segment’s long-term debt consisted of $20 million of fixed-rate senior secured debt with a maturity date of November 30, 2016 and an interest rate of 7.75%. The debt is secured by all of the membership interests in Gill Ranch and is nonrecourse to NW Natural. Under Gill Ranch’s amended loan agreement with Prudential, $20 million of the variable-rate debt was retired in June 2014. As part of the amended agreement, the EBITDA covenant requirement is suspended through March 31, 2015 with lower EBITDA hurdles thereafter, and the debt service reserve requirement is fixed at $3 million.

Our outstanding debt does not trade in active markets. We estimate the fair value of our debt using utility companies with similar credit ratings, terms, and remaining maturities to our debt that actively trade in public markets. These valuations are based on Level 2 inputs as defined in the fair value hierarchy. See Note 2 in our 2013 Form 10-K.

The following table provides an estimate of the fair value of our long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date:



	June 30,				December 31,
In thousands	2014		2013		2013
Carrying amount	$	721,700	$	691,700	$	741,700
Estimated fair value	807,617		769,679		806,359

See Note 7 in our 2013 Form 10-K for more detail on our long-term debt.