2.2.0.25falsefalse11400 - Disclosure - Commitments and Contigenciestruefalsefalse1falsefalseUSDfalsefalse1/1/2011 - 3/31/2011 USD ($) USD ($) / shares $FROM_Jan01_2011_TO_Mar31_2011http://www.sec.gov/CIK0000073020duration2011-01-01T00:00:002011-03-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDpershareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2true0nwn_DisclosureCommitmentsAndContingenciesnwnfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseDisclosure - Commitments and Contingencies3false0us-gaap_CommitmentsAndContingenciesDisclosureTextBlockus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse0014.       Commitments and Contingencies Environmental Matters We own, or previously owned, properties that may require environmental remediation or action.  We accrue all material loss contingencies relating to these properties that we believe to be probable of assertion and reasonably estimable.  We continue to study and evaluate the extent of our potential environmental liabilities, but due to the numerous uncertainties surrounding the course of environmental remediation and the preliminary nature of several site investigations, in some cases, we may not be able to reasonably estimate the high end of the range of possible loss. In those cases we have disclosed the nature of the potential loss and the fact that the high end of the range cannot be reasonably estimated. We regularly review our environmental liability for each site where we may be exposed to remediation responsibilities.  The costs of environmental remediation are difficult to estimate.  A number of steps are involved in each environmental remediation effort, including site investigations, remediation, operations and maintenance, monitoring and site closure.  Each of these steps may, over time, involve a number of alternative actions, each of which can change the course and scope of the effort.  Many of these steps are dependent upon the approval and direction of federal and state environmental regulators.  The policies, determinations and directions of the regulators may develop and change over time and different regulators may take different positions on the various steps, creating further uncertainty as to the timing and scope of remediation activities.  In certain cases, in addition to us, there are a number of other potentially responsible parties, each of which, in proceedings and negotiations with other potentially responsible parties and regulators, may influence the course and scope of the remediation effort. The allocation of liabilities among the potentially responsible parties is often subject to dispute and can be highly uncertain.  The events giving rise to environmental liabilities often occurred many decades ago, which complicates the determination of allocating liabilities among potentially responsible parties.  Site investigations and remediation efforts often develop slowly over many years.  In addition, disputes may arise between potentially responsible parties and regulators as to the severity of particular environmental matters and what remediation efforts are appropriate.  These disputes could lead to adversarial administrative proceedings or litigation, with uncertain outcomes. We estimate the range of loss for environmental liabilities using current technology, enacted laws and regulations, industry experience gained at similar sites and an assessment of the probable level of involvement and financial condition of other potentially responsible parties.  Unless there is an estimate within this range of possible losses that is more likely than other cost estimates, we record the liability at the lower end of this range.  It is likely that changes in these estimates and ranges will occur throughout the remediation process for each of these sites due to uncertainty concerning our responsibility, the complexity of environmental laws and regulations and the selection of compliance alternatives.  The status of each of the sites currently under investigation is provided below. Gasco site. We own property in Multnomah County, Oregon that is the site of a former gas manufacturing plant that was closed in 1956 (Gasco site). The Gasco site has been under investigation by us for environmental contamination under the Oregon Department of Environmental Quality's (ODEQ) Voluntary Clean-Up Program. In June 2003, we filed a Feasibility Scoping Plan and an Ecological and Human Health Risk Assessment with the ODEQ, which outlined a range of remedial alternatives for the most contaminated portion of the Gasco site. In May 2007, we completed a revised Remediation Investigation Report and submitted it to the ODEQ for review.  We also submitted a Focused Feasibility Study (FFS) for the groundwater source control portion of the Gasco site, which ODEQ conditionally approved in March 2008, subject to the submission of additional information. We provided that information to ODEQ and are now working with the agency on the final design for the source control system. Based on the information currently available for groundwater source control at the Gasco site and our current assumptions regarding remediation, we have estimated a range of liability between $11 million and $30 million, for which we have recorded an accrued liability of $11.8 million at March 31, 2011. The range of liability will be reassessed when ODEQ makes a final source control design decision. In addition to groundwater source control, we signed a joint Order on Consent with the Environmental Protection Agency (EPA), which requires the design of remedial action for sediments from the Gasco site. This design project is underway. We also have other investigation and clean-up work, including work on the uplands portion of the Gasco site, that we expect to be required. For the sediments project and other work, we have recorded an additional accrued liability of $38.0 million, which reflects the low end of the range of potential liability. We have accrued at the low end of the range of potential liability for the sediments project and other environmental work at the Gasco site because no amount within the range is considered to be more likely than another, and the high end of the range cannot reasonably be estimated. Siltronic site. We previously owned property adjacent to the Gasco site that now is the location of a manufacturing plant owned by Siltronic Corporation (the Siltronic site). We are currently conducting an investigation of manufactured gas plant wastes on the uplands at this site for the ODEQ.  The liability accrued at March 31, 2011 for the Siltronic site is $1 million, which is at the low end of the range of potential liability because no amount within the range is considered to be more likely than another, and the high end of the range cannot reasonably be estimated. Portland Harbor site. In 1998, the ODEQ and the EPA completed a study of sediments in a 5.5-mile segment of the Willamette River (Portland Harbor) that includes an area adjacent to the Gasco and Siltronic sites. The Portland Harbor was listed by the EPA as a Superfund site in 2000 and we were notified that we are a potentially responsible party. We then joined with other potentially responsible parties, referred to as the Lower Willamette Group, to fund environmental studies in the Portland Harbor. Subsequently, the EPA approved a Programmatic Work Plan, Field Sampling Plan and Quality Assurance Project Plan for the Portland Harbor Remedial Investigation/Feasibility Study (RI/FS), completion of which is scheduled for 2011. The EPA and the Lower Willamette Group are conducting focused studies on approximately nine miles of the lower Willamette River, including the 5.5-mile segment previously studied by the EPA. In August 2008, we signed a cooperative agreement to participate in a phased natural resource damage assessment, with the intent to identify what, if any, additional information is necessary to estimate further liabilities sufficient to support an early restoration-based settlement of natural resource damage claims.  As of March 31, 2011, we have a liability accrued of $8 million for this site, which is at the low end of the range of the potential liability because no amount within the range is considered to be more likely than another, and the high end of the range cannot reasonably be estimated. Central Service Center site. In 2006, we received notice from the ODEQ that our Central Service Center in southeast Portland (Central Service Center site) was assigned a high priority for further environmental investigation. Previously there were three manufactured gas storage tanks on the premises. The ODEQ believes there could be site contamination associated with releases of condensate from stored manufactured gas as a result of historic gas handling practices. In the early 1990s, we excavated waste piles and much of the contaminated surface soils and removed accessible waste from some of the abandoned piping. In early 2008, we received notice that this site was added to the ODEQ's list of sites where releases of hazardous substances have been confirmed and to its list where additional investigation or cleanup is necessary. We are currently performing an environmental investigation of the property with the ODEQ's Independent Cleanup Pathway.  As of March 31, 2011, we have a liability accrued of $0.5 million for investigation at this site. The estimate is at the low end of the range of potential liability because no amount within the range is considered to be more likely than another and the high end of the range cannot reasonably be estimated. Front Street site. The Front Street site was the former location of a gas manufacturing plant we operated. It is near but outside the geographic scope of the current Portland Harbor site sediment studies. The EPA directed the Lower Willamette Group to collect a series of surface and subsurface sediment samples off the river bank adjacent to where that facility was located. Based on the results of that sampling, the EPA notified the Lower Willamette Group that additional sampling would be required. As the Front Street site is upstream from the Portland Harbor site, the EPA agreed that it could be managed separately from the Portland Harbor site under ODEQ authority.  Work plans for source control investigation and a historical report were submitted to ODEQ and initial studies were completed.  In 2010, ODEQ required additional studies which are underway.  As of March 31, 2011, we have an estimated liability accrued of $0.9 million for the study of the sediments and riverbank groundwater and soils at the site.  The estimate is at the low end of the range of potential liability because no amount within the range is considered to be more likely than another and the high end of the range cannot reasonably be estimated. Oregon Steel Mills site. See “Legal Proceedings,” below. Accrued Liabilities Relating to Environmental Sites. The following table summarizes the accrued liabilities relating to environmental sites at March 31, 2011 and 2010 and December 31 2010:<div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 20px"><td style="width: 20px; text-align:left;border-color:#000000;min-width:20px;"> </td><td style="width: 160px; text-align:left;border-color:#000000;min-width:160px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td colspan="7" style="width: 250px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:250px;">Current Liabilities</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td colspan="7" style="width: 250px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:250px;">Non-Current Liabilities</td></tr><tr style="height: 20px"><td style="width: 20px; text-align:left;border-color:#000000;min-width:20px;"> </td><td style="width: 160px; text-align:left;border-color:#000000;min-width:160px;"> </td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:70px;">Mar. 31,</td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:70px;">Mar. 31,</td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:70px;">Dec. 31,</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:70px;">Mar. 31,</td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:70px;">Mar. 31,</td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:70px;">Dec. 31,</td></tr><tr style="height: 20px"><td colspan="2" style="width: 180px; text-align:left;border-color:#000000;min-width:180px;">Thousands</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:70px;">2011</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:70px;">2010</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:70px;">2010</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:70px;">2011</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:70px;">2010</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:70px;">2010</td></tr><tr style="height: 20px"><td colspan="2" style="width: 180px; text-align:left;border-color:#000000;min-width:180px;">Gasco site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 13,718</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 9,924</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 11,366</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 36,099</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 42,165</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 38,921</td></tr><tr style="height: 20px"><td colspan="2" style="width: 180px; text-align:left;border-color:#000000;min-width:180px;">Siltronic site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 730</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 679</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 720</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 291</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 508</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 201</td></tr><tr style="height: 20px"><td colspan="2" style="width: 180px; text-align:left;border-color:#000000;min-width:180px;">Portland Harbor site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 2,219</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 1,873</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 2,304</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 5,829</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 7,041</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 5,784</td></tr><tr style="height: 20px"><td colspan="2" style="width: 180px; text-align:left;border-color:#000000;min-width:180px;">Central Service Center site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 5</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 5</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 5</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 501</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 511</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 510</td></tr><tr style="height: 20px"><td colspan="2" style="width: 180px; text-align:left;border-color:#000000;min-width:180px;">Front Street site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> -</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 72</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 1</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 947</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 252</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 1,097</td></tr><tr style="height: 20px"><td colspan="2" style="width: 180px; text-align:left;border-color:#000000;min-width:180px;">Other sites</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:70px;"> -</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:70px;"> -</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:70px;"> -</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 117</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 106</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 108</td></tr><tr style="height: 21px"><td style="width: 20px; text-align:left;border-color:#000000;min-width:20px;"> </td><td style="width: 160px; text-align:left;border-color:#000000;min-width:160px;">Total</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:70px;"> 16,672</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:70px;"> 12,553</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:70px;"> 14,396</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:70px;"> 43,784</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:70px;"> 50,583</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 70px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:70px;"> 46,621</td></tr></table></div>Regulatory and Insurance Recovery for Environmental Costs.  In May 2003, the Public Utility Commission of Oregon (OPUC) approved our request to defer unreimbursed environmental costs associated with certain named sites, including those described above.  Beginning in 2006, the OPUC granted us additional authorization to accrue interest on deferred environmental cost balances, subject to an annual demonstration that we have maximized our insurance recovery or made substantial progress in securing insurance recovery for unrecovered environmental expenses. Through a series of extensions, the authorized cost deferral and interest accrual was extended through January 2010.  We have filed a request with the OPUC to extend this deferral, and expect authorization during the second quarter of 2011. In addition, we filed a request with the Washington Utilities and Transportation Commission (WUTC) in February 2011 to defer certain environmental costs associated with services provided to Washington customers, and expect an order from the WUTC during the second quarter of 2011. On a cumulative basis, we have recognized a total of $106.3 million for environmental costs, including legal, investigation, monitoring and remediation costs, including $4.9 million accrued and paid prior to regulatory deferral order approval.  At March 31, 2011, we had a regulatory asset of $117.5 million, which includes $47.1 million of total paid expenditures to date, $60.5 million for additional environmental costs expected to be paid in the future and accrued interest of $15.3 million, partially offset by $5.4 million of environmental costs expensed in prior years.  See table below. In December 2010, NW Natural commenced litigation against certain of its historical liability insurers in Multnomah County Circuit Court, State of Oregon, Case Number 1012-17532. The defendants include Associated Electric & Gas Insurance Services Limited, Allianz Global Risk US Insurance Company, certain underwriters at Lloyd's London, certain London market insurance companies and ten other insurance companies. In the suit, NW Natural alleges that the defendant insurance companies issued third party liability insurance policies to NW Natural and that the defendants have breached the terms of those policies by failing to indemnify NW Natural for liabilities arising from environmental contamination at certain sites caused or alleged to be caused by its historical operations.  NW Natural seeks damages in excess of $40 million in losses it has incurred to date, as well as declaratory relief for additional losses it expects to incur in the future. After seeking recovery of our environmental costs from our insurers, we believe recovery of the remainder of our deferred charges, if any, is probable through the regulatory process. Our regulatory asset will be reduced by the amount of any corresponding insurance recoveries. We continue to anticipate that our overall insurance recovery effort will extend over several years. We anticipate that our regulatory recovery of environmental cost deferrals will not be initiated within the next 12 months because we do not expect to have concluded our insurance recovery efforts during that time period, and because recovery would be expected to occur through the implementation of new rates through a general rate proceeding. As such we have classified our regulatory assets for environmental cost deferrals as non-current.  The following table summarizes the non-current regulatory assets relating to environmental sites at March 31, 2011 and 2010 and December 31, 2010:<div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 20px"><td style="width: 20px; text-align:left;border-color:#000000;min-width:20px;"> </td><td style="width: 280px; text-align:left;border-color:#000000;min-width:280px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td colspan="7" style="width: 400px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:400px;">Non-Current Regulatory Assets</td></tr><tr style="height: 20px"><td style="width: 20px; text-align:left;border-color:#000000;min-width:20px;"> </td><td style="width: 280px; text-align:left;border-color:#000000;min-width:280px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:120px;">March 31,</td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:120px;">March 31,</td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:120px;">December 31,</td></tr><tr style="height: 20px"><td colspan="2" style="width: 300px; text-align:left;border-color:#000000;min-width:300px;">Thousands</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:120px;">2011</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:120px;">2010</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:120px;">2010</td></tr><tr style="height: 20px"><td colspan="2" style="width: 300px; text-align:left;border-color:#000000;min-width:300px;">Gasco site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 120px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:120px;"> 76,338</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 120px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:120px;"> 70,411</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 120px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:120px;"> 74,205</td></tr><tr style="height: 20px"><td colspan="2" style="width: 300px; text-align:left;border-color:#000000;min-width:300px;">Siltronic site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 3,440</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 3,020</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 3,174</td></tr><tr style="height: 20px"><td colspan="2" style="width: 300px; text-align:left;border-color:#000000;min-width:300px;">Portland Harbor site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 34,732</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 32,140</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 33,940</td></tr><tr style="height: 20px"><td colspan="2" style="width: 300px; text-align:left;border-color:#000000;min-width:300px;">Central Service Center site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 558</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 550</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 553</td></tr><tr style="height: 20px"><td colspan="2" style="width: 300px; text-align:left;border-color:#000000;min-width:300px;">Front Street site</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 2,042</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 1,032</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; text-align:right;border-color:#000000;min-width:120px;"> 2,020</td></tr><tr style="height: 20px"><td colspan="2" style="width: 300px; text-align:left;border-color:#000000;min-width:300px;">Other sites</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:120px;"> 434</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:120px;"> 384</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 120px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:120px;"> 420</td></tr><tr style="height: 21px"><td style="width: 20px; text-align:left;border-color:#000000;min-width:20px;"> </td><td style="width: 280px; text-align:left;border-color:#000000;min-width:280px;">Total</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 120px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:120px;"> 117,544</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 120px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:120px;"> 107,537</td><td style="width: 10px; text-align:left;border-color:#000000;min-width:10px;"> </td><td style="width: 10px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:left;border-color:#000000;min-width:10px;">$</td><td style="width: 120px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:120px;"> 114,312</td></tr></table></div>Legal Proceedings We are subject to claims and litigation arising in the ordinary course of business. Although the final outcome of any of these legal proceedings cannot be predicted with certainty, including the matter described below, we do not expect that the ultimate disposition of any of these matters will have a material effect on our financial condition, results of operations or cash flows. Oregon Steel Mills site. In 2004, NW Natural was served with a third-party complaint by the Port of Portland (Port) in a Multnomah County Circuit Court case, Oregon Steel Mills, Inc. v. The Port of Portland. The Port alleges that in the 1940s and 1950s petroleum wastes generated by our predecessor, Portland Gas & Coke Company, and 10 other third-party defendants were disposed of in a waste oil disposal facility operated by the United States or Shaver Transportation Company on property then owned by the Port and now owned by Oregon Steel Mills. The complaint seeks contribution for unspecified past remedial action costs incurred by the Port regarding the former waste oil disposal facility as well as a declaratory judgment allocating liability for future remedial action costs. No date has been set for trial and discovery is ongoing. Although the final outcome of this proceeding cannot be predicted with certainty, we do not expect that the ultimate disposition of this matter will have a material effect on our financial condition, results of operations or cash flows.14.       Commitments and Contingencies Environmental Matters We own, or previously owned, properties that mayfalsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIncludes disclosure of commitments and contingencies. This element may be used as a single block of text to encapsulate the entire disclosure including data and tables.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 14 -Paragraph 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 9, 10, 11, 12 falsefalseCommitments and Contingencies Text Block12Commitments and ContigenciesUnKnownUnKnownUnKnownUnKnownfalsetrue