Environmental Matters (Tables)

3 Months Ended

Mar. 31, 2019

Environmental Remediation Obligations [Abstract]

Schedule of Environmental Loss Contingencies by Site

The following table summarizes information regarding liabilities related to environmental sites, which are recorded in other current liabilities and other noncurrent liabilities in NW Natural's balance sheet:



	Current Liabilities						Non-Current Liabilities
	March 31,				December 31,		March 31,				December 31,
In thousands	2019		2018		2018		2019		2018		2018
Portland Harbor site:
Gasco/Siltronic Sediments	$	4,595	$	2,797	$	5,117	$	44,427	$	45,015	$	44,351
Other Portland Harbor	2,299		1,769		2,600		5,958		3,928		6,273
Gasco/Siltronic Upland site	11,951		11,408		13,983		43,800		46,769		44,830
Central Service Center site	10		25		10		—		—		—
Front Street site	11,288		764		11,402		—		10,720		3
Oregon Steel Mills	—		—		—		179		179		179
Total	$	30,143	$	16,763	$	33,112	$	94,364	$	106,611	$	95,636

Environmental Regulatory Table

The following table presents information regarding the total regulatory asset deferred:



	March 31,						December 31,
In thousands	2019			2018			2018
Deferred costs and interest ⁽¹⁾	$	36,874		$	44,686		$	41,883
Accrued site liabilities ⁽²⁾	124,133			122,962			128,369
Insurance proceeds and interest	(89,305		)	(95,100		)	(88,502		)
Total regulatory asset deferral⁽¹⁾	$	71,702		$	72,548		$	81,750
Current regulatory assets⁽³⁾	5,090			5,818			5,601
Long-term regulatory assets⁽³⁾	66,612			66,730			76,149


⁽¹⁾	Includes pre-review and post-review deferred costs, amounts currently in amortization, and interest, net of amounts collected from customers.


⁽²⁾	Excludes 3.32% of the Front Street site liability, or $0.4 million in 2019 and $0.4 million in 2018, as the OPUC only allows recovery of 96.68% of costs for those sites allocable to Oregon, including those that historically served only Oregon customers.

⁽³⁾

Environmental costs relate to specific sites approved for regulatory deferral by the OPUC and WUTC. In Oregon, NW Natural earns a carrying charge on cash amounts paid, whereas amounts accrued but not yet paid do not earn a carrying charge until expended. It also accrues a carrying charge on insurance proceeds for amounts owed to customers. In Washington, a carrying charge related to deferred amounts will be determined in a future proceeding. Current environmental costs represent remediation costs management expects to collect from customers in the next 12 months. Amounts included in this estimate are still subject to a prudence and earnings test review by the OPUC and do not include the $5.0 million tariff rider. The amounts allocable to Oregon are recoverable through NGD rates, subject to an earnings test.