EQUITY METHOD INVESTMENTS

Our equity method investments consist of the following (in thousands):



	December 31,
	2017		2016
White Cliffs	$	266,362	$	281,734
Glass Mountain	—		133,622
NGL Energy	18,919		18,933
Total equity method investments	$	285,281	$	434,289

Our earnings from equity method investments consist of the following (in thousands):



	Year Ended December 31,
	2017			2016		2015
White Cliffs	$	59,851		$	69,007	$	70,238
Glass Mountain	7,494			2,562		6,117
NGL Energy⁽¹⁾	(14		)	2,188		5,031
Total earnings from equity method investments	$	67,331		$	73,757	$	81,386

(1) Excluding a loss on issuance of common units of $41.0 thousand for the year ended December 31, 2016, and a gain on the issuance of common units of $6.4 million for the year ended December 31, 2015.

Cash distributions received from equity method investments consist of the following (in thousands):



	Year Ended December 31,
	2017		2016		2015
White Cliffs	$	77,511	$	88,839	$	86,845
Glass Mountain	18,011		10,456		13,623
NGL Energy	—		4,873		19,074
Total cash distributions received from equity method investments	$	95,522	$	104,168	$	119,542

White Cliffs

We own a 51% interest in White Cliffs, which we account for under the equity method. The equity in earnings of White Cliffs for the years ended December 31, 2017, 2016 and 2015 reported in our consolidated statements of operations and comprehensive income (loss) is less than 51% of the net income of White Cliffs for the same period. This is primarily due to certain general and administrative expenses we incur in managing the operations of White Cliffs that the other members are not obligated to share. In addition, our equity in earnings is also impacted by the elimination of revenue on the sale of inventory to White Cliffs. Revenue related to inventory transactions with White Cliffs is deferred until a sale of the inventory has been made with a third party.

The members of White Cliffs are required to contribute capital to White Cliffs to fund various projects. For the years ended December 31, 2017, 2016 and 2015, we contributed $1.4 million, $2.2 million and $42.8 million, respectively, to White Cliffs capital projects.

Our membership interest in White Cliffs is significant as defined by Securities and Exchange Commission’s Regulation S-X Rule 1-02(w). Accordingly, as required by Regulation S-X Rule 3-09, we have included the audited financial statements of White Cliffs as of December 31, 2017 and 2016 and for each of the three years in the period ended December 31, 2017 as an exhibit to this Form 10-K.

Glass Mountain

On December 22, 2017, we completed the sale of our equity method investment in Glass Mountain for $300 million, subject to working capital and other adjustments. We recorded a pre-tax gain on disposal of $150.3 million, which was reported in "loss on disposal or impairment, net" in our consolidated statement of operations and comprehensive income (loss). Proceeds from the sale were used to repay borrowings on SemGroup's revolving credit facility.

NGL Energy

At December 31, 2017, we held an 11.78% interest in the general partner of NGL Energy which is being accounted for under the equity method in accordance with ASC 323-30-S99-1, as our ownership is in excess of the 3 to 5 percent interest which is generally considered to be more than minor.

The general partner of NGL Energy is not a publicly traded company. The information below pertains to our general partner interest, and previously held limited partner interest, in NGL Energy.

NGL Energy unit issuances and sales of NGL Energy units

During the year ended December 31, 2016, we sold our remaining 4,652,568 NGL Energy limited partner units for $13.00 per unit, or $60.5 million, and recorded a $9.1 million gain on disposal. During the year ended December 31, 2015, we sold 1,999,533 of our NGL Energy common units for $56.3 million, net of related costs of $0.5 million. We recorded a net gain of $14.5 million. Subsequent to these disposals, we no longer hold a limited partner interest in NGL Energy. Gains on disposal of NGL Energy limited partner units are included in "loss (gain) on sale or impairment of non-operated equity method investment" in our consolidated statements of operations and comprehensive income (loss).

During the years ended December 31, 2016 and 2015, our limited partnership interest was diluted in connection with NGL Energy common unit issuances. Accordingly, we recorded a non-cash loss of $41.0 thousand for the year ended December 31, 2016 and a non-cash gain of $6.4 million for the year ended December 31, 2015 related to these transactions, which are included in "gain (loss) on issuance of common units by equity method investee" in our consolidated statements of operations and comprehensive income (loss).

Other-than-temporary impairment of equity method investment in NGL Energy

During the year ended 2016, we recorded an impairment of $39.8 million to our investment in the limited partner units of NGL Energy subsequent to NGL Energy's April 21, 2016 announcement of a reduction in its quarterly distribution and lowering of financial performance guidance. These units were subsequently sold in the second quarter of 2016. The impairment was included in "loss (gain) on sale or impairment of non-operated equity method investment" in our consolidated statements of operations and comprehensive income (loss).