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Commitments And Contingencies | 12 Months Ended
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Dec. 31, 2015
Commitments And Contingencies | COMMITMENTS AND CONTINGENCIES (a) Capital Purchase Obligations - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects. IPL’s projects include generation maintenance and performance improvements for Marshalltown Combustion Turbine Units 1-3. WPL’s projects include the installation of a scrubber and baghouse at Edgewater Unit 5 to reduce SO2 and mercury emissions, generation maintenance and performance improvements at Columbia Units 1 and 2, and the installation of an SCR system at Columbia Unit 2 to reduce NOx emissions at the EGU. At December 31, 2015, Alliant Energy’s, IPL’s and WPL’s minimum future commitments related to certain contractual obligations for these projects were $23 million, $7 million and $16 million, respectively. (b) Operating Expense Purchase Obligations - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. Other operating expense purchase obligations with various vendors provide other goods and services. At December 31, 2015, minimum future commitments related to these operating expense purchase obligations were as follows (in millions):
Alliant Energy | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |  | Total
Purchased power (a): |  |  |  |  |  |  |  |  |  |  |  |  |
DAEC (IPL) (b) |  | $125 |  |  |  | $138 |  |  |  | $131 |  |  |  | $143 |  |  |  | $133 |  |  |  | $749 |  |  |  | $1,419 |
Other | 77 |  |  | 44 |  |  | 44 |  |  | — |  |  | — |  |  | — |  |  | 165 |
| 202 |  |  | 182 |  |  | 175 |  |  | 143 |  |  | 133 |  |  | 749 |  |  | 1,584 |
Natural gas | 173 |  |  | 82 |  |  | 52 |  |  | 43 |  |  | 32 |  |  | 16 |  |  | 398 |
Coal (c) | 129 |  |  | 76 |  |  | 50 |  |  | 12 |  |  | — |  |  | — |  |  | 267 |
SO2 emission allowances | 14 |  |  | 8 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 22 |
Other (d) | 6 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 7 |  |  | 21 |
|  | $524 |  |  |  | $350 |  |  |  | $279 |  |  |  | $200 |  |  |  | $167 |  |  |  | $772 |  |  |  | $2,292 |
IPL | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |  | Total
Purchased power (a): |  |  |  |  |  |  |  |  |  |  |  |  |
DAEC (b) |  | $125 |  |  |  | $138 |  |  |  | $131 |  |  |  | $143 |  |  |  | $133 |  |  |  | $749 |  |  |  | $1,419 |
Other | 1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 1 |
| 126 |  |  | 138 |  |  | 131 |  |  | 143 |  |  | 133 |  |  | 749 |  |  | 1,420 |
Natural gas | 95 |  |  | 42 |  |  | 35 |  |  | 28 |  |  | 18 |  |  | 10 |  |  | 228 |
Coal (c) | 70 |  |  | 30 |  |  | 17 |  |  | 4 |  |  | — |  |  | — |  |  | 121 |
SO2 emission allowances | 14 |  |  | 8 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 22 |
Other (d) | 1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 1 |
| $306 |  |  | $218 |  |  |  | $183 |  |  |  | $175 |  |  |  | $151 |  |  |  | $759 |  |  |  | $1,792 |
WPL | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |  | Total
Purchased power (a) |  | $76 |  |  |  | $44 |  |  |  | $44 |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $164 |
Natural gas | 78 |  |  | 40 |  |  | 17 |  |  | 15 |  |  | 14 |  |  | 6 |  |  | 170 |
Coal (c) | 59 |  |  | 46 |  |  | 33 |  |  | 8 |  |  | — |  |  | — |  |  | 146 |
Other (d) | 2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 2 |
|  | $215 |  |  |  | $130 |  |  |  | $94 |  |  |  | $23 |  |  |  | $14 |  |  |  | $6 |  |  |  | $482 |
(a) | Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. Refer to Note 18 for additional information on purchased power transactions.
(b) | Includes commitments incurred under a PPA, which grants IPL rights to purchase up to 431 MWs of capacity and the resulting energy from DAEC for a term through December 31, 2025. If energy delivered is less than the targeted energy amount, an adjustment payment will be made to IPL, which will be reflected in IPL’s fuel adjustment clause.
(c) | Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2015 regarding expected future usage, which is subject to change.
(d) | Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2015.
Certain contracts are considered leases and are therefore not included here, but are included in Note 10. (c) Legal Proceedings - Flood Damage Claims - In 2013, several plaintiffs purporting to represent a class of residential and commercial property owners filed a complaint against CRANDIC, Alliant Energy and various other defendants in the Iowa District Court for Linn County. Plaintiffs assert claims of negligence and strict liability based on their allegations that CRANDIC (along with other defendants) caused or exacerbated flooding of the Cedar River in June 2008. On February 12, 2016, the Iowa District Court for Linn County ruled in favor of Alliant Energy and CRANDIC and dismissed all claims against them, resulting in no loss. Plaintiffs have 30 days to seek an appeal of this decision. Other - Alliant Energy, IPL and WPL are involved in other legal and administrative proceedings before various courts and agencies with respect to matters arising in the ordinary course of business. Although unable to predict the outcome of these matters, Alliant Energy, IPL and WPL believe that appropriate reserves have been established and final disposition of these actions will not have a material effect on their financial condition or results of operations. (d) Guarantees and Indemnifications - RMT - In 2013, Alliant Energy sold RMT. RMT provided renewable energy services, including construction and high voltage connection services for wind and solar projects. As part of the sale, Alliant Energy indemnified the buyer for any claims, including claims of warranty under the project obligations that were commenced or are based on actions that occurred prior to the sale, except for liabilities already accounted for through adjustments to the purchase price. The indemnification obligations either cease to exist when the statute of limitation for such claims is met or, in the case of RMT’s projects, when the warranty period under the agreements expires. The contractual warranty periods for RMT’s projects generally range from 12 to 60 months with the latest expiring in 2016. Limited warranties may be extended in certain cases for warranty work performed. Alliant Energy also continues to guarantee RMT’s performance obligations related to certain of RMT’s projects that were commenced prior to Alliant Energy’s sale of RMT. As of December 31, 2015, Alliant Energy had $123 million of performance guarantees outstanding with $48 million and $75 million currently expected to expire in 2016 and 2017, respectively. The expiration of these performance guarantees may be extended depending on when all valid warranty claims are resolved for the respective projects. Although Alliant Energy has received warranty claims related to certain of these projects, it does not currently believe that material losses are both probable and reasonably estimated, and therefore, has not recognized any material liabilities related to these matters as of December 31, 2015. Alliant Energy does not currently believe that the range of future potential loss from any warranty claims will be material. Refer to Note 19 for further discussion of RMT, including amounts Alliant Energy recorded to “Operating expenses” in 2015 and 2014 related to certain warranty claims. Whiting Petroleum - In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Whiting Petroleum is an independent oil and gas company. Resources, as the successor to a predecessor entity that owned Whiting Petroleum, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under general partnership agreements in the oil and gas industry, including with respect to the future abandonment of certain platforms off the coast of California and related onshore plant and equipment owned by the partnerships. The guarantees do not include a maximum limit. As of December 31, 2015, the present value of the abandonment obligations is estimated at $28 million. Alliant Energy is not aware of any material liabilities related to these guarantees of which it is probable that Resources will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of December 31, 2015. IPL’s Minnesota Electric Distribution Assets - IPL provided indemnifications associated with the July 2015 sale of its Minnesota electric distribution assets for losses resulting from potential breach of IPL’s representations, warranties and obligations under the sale agreement. Alliant Energy and IPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. IPL has not recorded any material liabilities related to these indemnifications as of December 31, 2015. The general terms of the indemnifications provided by IPL included a maximum limit of $17 million and expire in October 2020. Refer to Note 3 for further discussion of the sale of IPL’s Minnesota electric distribution assets. (e) Environmental Matters - Alliant Energy, IPL and WPL are subject to environmental regulations as a result of their current and past operations. These regulations are designed to protect public health and the environment and have resulted in compliance, remediation, containment and monitoring obligations, which are recorded as environmental liabilities. At December 31, current environmental liabilities were included in “Other current liabilities” and non-current environmental liabilities were included in “Other liabilities” on the balance sheets as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
Current environmental liabilities |  | $2.7 |  |  |  | $2.0 |  |  |  | $1.7 |  |  |  | $1.7 |  |  |  | $1.0 |  |  |  | $0.3 |
Non-current environmental liabilities | 12.8 |  |  | 13.5 |  |  | 11.2 |  |  | 11.9 |  |  | 1.5 |  |  | 1.6 |
|  | $15.5 |  |  |  | $15.5 |  |  |  | $12.9 |  |  |  | $13.6 |  |  |  | $2.5 |  |  |  | $1.9 |
MGP Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. IPL and WPL are currently monitoring and/or remediating 24 and 5 sites, respectively. Environmental liabilities related to these MGP sites are recorded based upon periodic studies. Such amounts are based on the best current estimate of the remaining amount to be incurred for investigation, remediation and monitoring costs for those sites where the investigation process has been or is substantially completed, and the minimum of the estimated cost range for those sites where the investigation is in its earlier stages. There are inherent uncertainties associated with the estimated remaining costs for MGP projects primarily due to unknown site conditions and potential changes in regulatory agency requirements. It is possible that future cost estimates will be greater than current estimates as the investigation process proceeds and as additional facts become known. The amounts recognized as liabilities are reduced for expenditures incurred and are adjusted as further information develops or circumstances change. Costs of future expenditures for environmental remediation obligations are not discounted. At December 31, 2015, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Range of estimated future costs |  | $11 |  | - | $28 |  |  | $9 |  | - | $25 |  |  | $2 |  | - | $3
Current and non-current environmental liabilities | 15 |  | 13 |  | 2
Refer to Note 2 for discussion of regulatory assets recorded by IPL and WPL, which reflect the probable future rate recovery of MGP expenditures. Considering the current rate treatment, and assuming no material change therein, Alliant Energy, IPL and WPL believe that the clean-up costs incurred for these MGP sites will not have a material effect on their financial condition or results of operations. WPL Consent Decree - In 2009, the EPA sent a notice of violation to WPL as an owner and the operator of Edgewater, Nelson Dewey and Columbia alleging that the owners of such EGUs failed to comply with appropriate pre-construction review and permitting requirements and as a result violated the PSD program requirements, Title V Operating Permit requirements of the CAA and the Wisconsin SIP. In 2010, the Sierra Club filed complaints against WPL, as owner and operator of Nelson Dewey and Columbia, and separately as owner and operator of Edgewater, based on allegations that modifications were made at the facilities without complying with the PSD program requirements, Title V Operating Permit requirements of the CAA and state regulatory counterparts contained within the Wisconsin SIP designed to implement the CAA. In 2013, WPL, along with the other owners of Edgewater and Columbia, entered into a Consent Decree with the EPA and the Sierra Club to resolve the claims relating to Edgewater, Columbia and Nelson Dewey, while admitting no liability. In 2013, the Consent Decree was approved by the Western Wisconsin Court, thereby resolving all claims against WPL. Under the Consent Decree, WPL is required to install the following environmental controls systems:
• | SCR system at Edgewater Unit 5 by May 1, 2013 (placed in service in 2012);
• | Scrubbers and baghouses at Columbia Units 1 and 2 by December 31, 2014 (placed in service in 2014);
• | Scrubber and baghouse at Edgewater Unit 5 by December 31, 2016; and
• | SCR system at Columbia Unit 2 by December 31, 2018.
WPL is also required to fuel switch or retire Edgewater Unit 4 by December 31, 2018. In December 2015, WPL retired Nelson Dewey Units 1 and 2 and Edgewater Unit 3 consistent with the Consent Decree. In addition, the Consent Decree establishes emission rate limits for SO2, NOx and particulate matter for Columbia Units 1 and 2, Nelson Dewey Units 1 and 2, and Edgewater Units 4 and 5. The Consent Decree also includes annual plant-wide emission caps for SO2 and NOx for Columbia, Edgewater and Nelson Dewey. In addition, WPL will complete approximately $7 million in environmental mitigation projects. Final recovery of the costs expected to be incurred related to the Consent Decree will be decided by the PSCW in future rate cases or other proceedings. Alliant Energy and WPL currently expect to recover any material costs incurred by WPL related to compliance with the terms of the Consent Decree from WPL’s electric customers. IPL Consent Decree - In July 2015, IPL entered into a Consent Decree with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa to resolve potential claims regarding CAA issues associated with emissions from IPL’s coal-fired generating facilities in Iowa, while admitting no liability. In September 2015, the Consent Decree was approved by the Northern Iowa Court, thereby resolving all potential claims against IPL. Under the Consent Decree, IPL is required to install the following environmental controls systems:
• | Scrubber and baghouse at the Ottumwa Generating Station by December 31, 2015 (placed in service in 2014);
• | Scrubber and baghouse at the Lansing Generating Station by December 31, 2016 (scrubber was placed in service in June 2015 and baghouse was placed in service in 2010); and
• | SCR system or equivalent NOx reduction system at the Ottumwa Generating Station by December 31, 2019.
IPL is also required to fuel switch or retire the following EGUs:
• | M.L. Kapp Generating Station by August 31, 2015 (switched the fuel type from coal to natural gas in June 2015);
• | Prairie Creek Unit 4 by June 1, 2018;
• | Burlington Generating Station by December 31, 2021; and
• | Prairie Creek Units 1 and 3 by December 31, 2025.
In addition, IPL is required to either install combined cycle technology at, or retire, the Dubuque and Sutherland Generation Stations by June 1, 2019. IPL previously switched the fuel type from coal to natural gas at these EGUs. The Consent Decree also establishes SO2, NOx and particulate matter emission rate limits with varying averaging times for the Burlington, Lansing, M.L. Kapp, Ottumwa and Prairie Creek Generating Stations. In addition, the Consent Decree includes calendar-year SO2 and NOx emission caps for the Prairie Creek Generating Station, and calendar-year SO2 and NOx emission caps in aggregate for the Burlington, Dubuque, Lansing, M.L. Kapp, Ottumwa, Prairie Creek and Sutherland Generating Stations. Pursuant to the Consent Decree, IPL paid a civil penalty of $1 million in 2015 and will complete approximately $6 million in environmental mitigation projects. Alliant Energy and IPL currently expect to recover all material costs incurred by IPL related to the environmental control systems and environmental mitigation projects from IPL’s electric customers. The recovery of such costs will be decided by IPL’s regulators in future rate cases or other proceedings. Alliant Energy and IPL currently do not expect to recover costs related to the civil penalty from IPL’s electric customers. Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however future capital investments and/or modifications to EGUs to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters are included below, along with a brief description of these environmental rules. Air Quality - CSAPR is an emissions trading program that requires SO2 and NOx emissions reductions at certain IPL and WPL fossil-fueled EGUs through installation of environmental controls and/or purchases of allowances. Compliance with emission limits began in 2015, with additional emission limits reductions beginning in 2017. Alliant Energy, IPL and WPL are currently in compliance with the Phase I CSAPR emission limits. Ozone NAAQS Rule may require NOx emission reductions in certain non-attainment areas designated by the EPA. The EPA’s final designations of non-attainment areas for this rule are currently expected to be issued by October 2017. Compliance deadlines range from 2020 through 2037 depending on the level of ozone monitored in non-attainment areas. Sheboygan County in Wisconsin is currently the only non-attainment area in Alliant Energy’s service territory. WPL operates Edgewater and Sheboygan Falls in Sheboygan County, Wisconsin. Clean Air Act Section 111(d) establishes standards under Section 111(d) of the CAA, otherwise referred to as the Clean Power Plan, for states to follow in developing plans to reduce CO2 emissions from existing fossil-fueled EGUs. The standards include an interim compliance period from 2022 through 2029 and a final compliance requirement beginning in 2030. In February 2016, the Supreme Court issued a stay of the Clean Power Plan until pending legal challenges are resolved, which places implementation of the final standards on hold indefinitely. Clean Air Act Section 111(b) establishes standards under Section 111(b) of the CAA for CO2 emissions limits for certain new fossil-fueled EGUs. Marshalltown and WPL’s proposed Riverside expansion are expected to be impacted by these standards. Marshalltown is being constructed, and WPL’s proposed Riverside expansion is being designed, to achieve compliance with these standards. Water Quality - Section 316(b) of the Federal Clean Water Act regulates cooling water intake structures and minimizes adverse environmental impacts to fish and other aquatic life. Compliance will be incorporated during periodic facility permit renewal cycles, with final compliance anticipated by 2022. Effluent Limitation Guidelines require changes to discharge limits for wastewater from steam generating facilities. Compliance for existing steam generating facilities will be required after November 1, 2018 but before December 31, 2023, depending on each facility’s wastewater permit renewal cycle, and immediately upon operation for new steam generating facilities constructed after January 2016. Hydroelectric Fish Passage Device - WPL is currently required to install an agency-approved fish passage device at its Prairie du Sac hydro plant by December 31, 2020. Land and Solid Waste - CCR Rule establishes minimum criteria for disposing of CCR in landfills and surface impoundments (ash ponds), and allows for continued operation of ash ponds if they meet certain performance criteria. (f) Credit Risk - IPL and WPL provide regulated electricity and natural gas services to residential, commercial, industrial and wholesale customers in the Midwest region of the U.S. The geographic concentration of these customers did not contribute significantly to overall credit risk exposure. In addition, as a result of a diverse customer base, IPL and WPL did not have any significant credit risk concentration for receivables arising from the sale of electricity or natural gas services. Alliant Energy, IPL and WPL are subject to credit risk related to the ability of counterparties to meet their contractual payment obligations or the potential non-performance of counterparties to deliver contracted commodities and other goods or services at the contracted price. IPL and WPL are typically net buyers of commodities (primarily electricity, coal and natural gas) required to provide regulated electricity and natural gas services to their customers. As a result, IPL and WPL are also subject to credit risk related to their counterparties’ failures to deliver commodities at the contracted price. Credit policies are maintained to mitigate credit risk. These credit policies include evaluation of the financial condition of certain counterparties, use of credit risk-related contingent provisions in certain commodity agreements that require credit support from counterparties that exceed certain exposure limits, diversification of counterparties to reduce concentrations of credit risk and the use of standardized agreements that facilitate the netting of cash flows associated with certain counterparties. IPL has a PPA that grants it rights to purchase capacity and the resulting energy from DAEC through December 31, 2025. This PPA exposes Alliant Energy and IPL to risk of counterparty non-performance. However, financial risk is mitigated by IPL’s fuel-related cost recovery mechanisms. Refer to Note 16(b) for further discussion of the DAEC PPA. Based on these credit policies, counterparty diversification and utility cost recovery mechanisms, it is unlikely that counterparty non-performance would have a material effect on financial condition or results of operations. However, there is no assurance that these items will protect against all losses from counterparty non-performance. Refer to Notes 5(a) and 15 for details of allowances for doubtful accounts and credit risk-related contingent features, respectively.
IPL [Member] |
Commitments And Contingencies | COMMITMENTS AND CONTINGENCIES (a) Capital Purchase Obligations - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects. IPL’s projects include generation maintenance and performance improvements for Marshalltown Combustion Turbine Units 1-3. WPL’s projects include the installation of a scrubber and baghouse at Edgewater Unit 5 to reduce SO2 and mercury emissions, generation maintenance and performance improvements at Columbia Units 1 and 2, and the installation of an SCR system at Columbia Unit 2 to reduce NOx emissions at the EGU. At December 31, 2015, Alliant Energy’s, IPL’s and WPL’s minimum future commitments related to certain contractual obligations for these projects were $23 million, $7 million and $16 million, respectively. (b) Operating Expense Purchase Obligations - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. Other operating expense purchase obligations with various vendors provide other goods and services. At December 31, 2015, minimum future commitments related to these operating expense purchase obligations were as follows (in millions):
Alliant Energy | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |  | Total
Purchased power (a): |  |  |  |  |  |  |  |  |  |  |  |  |
DAEC (IPL) (b) |  | $125 |  |  |  | $138 |  |  |  | $131 |  |  |  | $143 |  |  |  | $133 |  |  |  | $749 |  |  |  | $1,419 |
Other | 77 |  |  | 44 |  |  | 44 |  |  | — |  |  | — |  |  | — |  |  | 165 |
| 202 |  |  | 182 |  |  | 175 |  |  | 143 |  |  | 133 |  |  | 749 |  |  | 1,584 |
Natural gas | 173 |  |  | 82 |  |  | 52 |  |  | 43 |  |  | 32 |  |  | 16 |  |  | 398 |
Coal (c) | 129 |  |  | 76 |  |  | 50 |  |  | 12 |  |  | — |  |  | — |  |  | 267 |
SO2 emission allowances | 14 |  |  | 8 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 22 |
Other (d) | 6 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 7 |  |  | 21 |
|  | $524 |  |  |  | $350 |  |  |  | $279 |  |  |  | $200 |  |  |  | $167 |  |  |  | $772 |  |  |  | $2,292 |
IPL | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |  | Total
Purchased power (a): |  |  |  |  |  |  |  |  |  |  |  |  |
DAEC (b) |  | $125 |  |  |  | $138 |  |  |  | $131 |  |  |  | $143 |  |  |  | $133 |  |  |  | $749 |  |  |  | $1,419 |
Other | 1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 1 |
| 126 |  |  | 138 |  |  | 131 |  |  | 143 |  |  | 133 |  |  | 749 |  |  | 1,420 |
Natural gas | 95 |  |  | 42 |  |  | 35 |  |  | 28 |  |  | 18 |  |  | 10 |  |  | 228 |
Coal (c) | 70 |  |  | 30 |  |  | 17 |  |  | 4 |  |  | — |  |  | — |  |  | 121 |
SO2 emission allowances | 14 |  |  | 8 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 22 |
Other (d) | 1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 1 |
| $306 |  |  | $218 |  |  |  | $183 |  |  |  | $175 |  |  |  | $151 |  |  |  | $759 |  |  |  | $1,792 |
WPL | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |  | Total
Purchased power (a) |  | $76 |  |  |  | $44 |  |  |  | $44 |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $164 |
Natural gas | 78 |  |  | 40 |  |  | 17 |  |  | 15 |  |  | 14 |  |  | 6 |  |  | 170 |
Coal (c) | 59 |  |  | 46 |  |  | 33 |  |  | 8 |  |  | — |  |  | — |  |  | 146 |
Other (d) | 2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 2 |
|  | $215 |  |  |  | $130 |  |  |  | $94 |  |  |  | $23 |  |  |  | $14 |  |  |  | $6 |  |  |  | $482 |
(a) | Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. Refer to Note 18 for additional information on purchased power transactions.
(b) | Includes commitments incurred under a PPA, which grants IPL rights to purchase up to 431 MWs of capacity and the resulting energy from DAEC for a term through December 31, 2025. If energy delivered is less than the targeted energy amount, an adjustment payment will be made to IPL, which will be reflected in IPL’s fuel adjustment clause.
(c) | Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2015 regarding expected future usage, which is subject to change.
(d) | Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2015.
Certain contracts are considered leases and are therefore not included here, but are included in Note 10. (c) Legal Proceedings - Flood Damage Claims - In 2013, several plaintiffs purporting to represent a class of residential and commercial property owners filed a complaint against CRANDIC, Alliant Energy and various other defendants in the Iowa District Court for Linn County. Plaintiffs assert claims of negligence and strict liability based on their allegations that CRANDIC (along with other defendants) caused or exacerbated flooding of the Cedar River in June 2008. On February 12, 2016, the Iowa District Court for Linn County ruled in favor of Alliant Energy and CRANDIC and dismissed all claims against them, resulting in no loss. Plaintiffs have 30 days to seek an appeal of this decision. Other - Alliant Energy, IPL and WPL are involved in other legal and administrative proceedings before various courts and agencies with respect to matters arising in the ordinary course of business. Although unable to predict the outcome of these matters, Alliant Energy, IPL and WPL believe that appropriate reserves have been established and final disposition of these actions will not have a material effect on their financial condition or results of operations. (d) Guarantees and Indemnifications - RMT - In 2013, Alliant Energy sold RMT. RMT provided renewable energy services, including construction and high voltage connection services for wind and solar projects. As part of the sale, Alliant Energy indemnified the buyer for any claims, including claims of warranty under the project obligations that were commenced or are based on actions that occurred prior to the sale, except for liabilities already accounted for through adjustments to the purchase price. The indemnification obligations either cease to exist when the statute of limitation for such claims is met or, in the case of RMT’s projects, when the warranty period under the agreements expires. The contractual warranty periods for RMT’s projects generally range from 12 to 60 months with the latest expiring in 2016. Limited warranties may be extended in certain cases for warranty work performed. Alliant Energy also continues to guarantee RMT’s performance obligations related to certain of RMT’s projects that were commenced prior to Alliant Energy’s sale of RMT. As of December 31, 2015, Alliant Energy had $123 million of performance guarantees outstanding with $48 million and $75 million currently expected to expire in 2016 and 2017, respectively. The expiration of these performance guarantees may be extended depending on when all valid warranty claims are resolved for the respective projects. Although Alliant Energy has received warranty claims related to certain of these projects, it does not currently believe that material losses are both probable and reasonably estimated, and therefore, has not recognized any material liabilities related to these matters as of December 31, 2015. Alliant Energy does not currently believe that the range of future potential loss from any warranty claims will be material. Refer to Note 19 for further discussion of RMT, including amounts Alliant Energy recorded to “Operating expenses” in 2015 and 2014 related to certain warranty claims. Whiting Petroleum - In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Whiting Petroleum is an independent oil and gas company. Resources, as the successor to a predecessor entity that owned Whiting Petroleum, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under general partnership agreements in the oil and gas industry, including with respect to the future abandonment of certain platforms off the coast of California and related onshore plant and equipment owned by the partnerships. The guarantees do not include a maximum limit. As of December 31, 2015, the present value of the abandonment obligations is estimated at $28 million. Alliant Energy is not aware of any material liabilities related to these guarantees of which it is probable that Resources will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of December 31, 2015. IPL’s Minnesota Electric Distribution Assets - IPL provided indemnifications associated with the July 2015 sale of its Minnesota electric distribution assets for losses resulting from potential breach of IPL’s representations, warranties and obligations under the sale agreement. Alliant Energy and IPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. IPL has not recorded any material liabilities related to these indemnifications as of December 31, 2015. The general terms of the indemnifications provided by IPL included a maximum limit of $17 million and expire in October 2020. Refer to Note 3 for further discussion of the sale of IPL’s Minnesota electric distribution assets. (e) Environmental Matters - Alliant Energy, IPL and WPL are subject to environmental regulations as a result of their current and past operations. These regulations are designed to protect public health and the environment and have resulted in compliance, remediation, containment and monitoring obligations, which are recorded as environmental liabilities. At December 31, current environmental liabilities were included in “Other current liabilities” and non-current environmental liabilities were included in “Other liabilities” on the balance sheets as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
Current environmental liabilities |  | $2.7 |  |  |  | $2.0 |  |  |  | $1.7 |  |  |  | $1.7 |  |  |  | $1.0 |  |  |  | $0.3 |
Non-current environmental liabilities | 12.8 |  |  | 13.5 |  |  | 11.2 |  |  | 11.9 |  |  | 1.5 |  |  | 1.6 |
|  | $15.5 |  |  |  | $15.5 |  |  |  | $12.9 |  |  |  | $13.6 |  |  |  | $2.5 |  |  |  | $1.9 |
MGP Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. IPL and WPL are currently monitoring and/or remediating 24 and 5 sites, respectively. Environmental liabilities related to these MGP sites are recorded based upon periodic studies. Such amounts are based on the best current estimate of the remaining amount to be incurred for investigation, remediation and monitoring costs for those sites where the investigation process has been or is substantially completed, and the minimum of the estimated cost range for those sites where the investigation is in its earlier stages. There are inherent uncertainties associated with the estimated remaining costs for MGP projects primarily due to unknown site conditions and potential changes in regulatory agency requirements. It is possible that future cost estimates will be greater than current estimates as the investigation process proceeds and as additional facts become known. The amounts recognized as liabilities are reduced for expenditures incurred and are adjusted as further information develops or circumstances change. Costs of future expenditures for environmental remediation obligations are not discounted. At December 31, 2015, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Range of estimated future costs |  | $11 |  | - | $28 |  |  | $9 |  | - | $25 |  |  | $2 |  | - | $3
Current and non-current environmental liabilities | 15 |  | 13 |  | 2
Refer to Note 2 for discussion of regulatory assets recorded by IPL and WPL, which reflect the probable future rate recovery of MGP expenditures. Considering the current rate treatment, and assuming no material change therein, Alliant Energy, IPL and WPL believe that the clean-up costs incurred for these MGP sites will not have a material effect on their financial condition or results of operations. WPL Consent Decree - In 2009, the EPA sent a notice of violation to WPL as an owner and the operator of Edgewater, Nelson Dewey and Columbia alleging that the owners of such EGUs failed to comply with appropriate pre-construction review and permitting requirements and as a result violated the PSD program requirements, Title V Operating Permit requirements of the CAA and the Wisconsin SIP. In 2010, the Sierra Club filed complaints against WPL, as owner and operator of Nelson Dewey and Columbia, and separately as owner and operator of Edgewater, based on allegations that modifications were made at the facilities without complying with the PSD program requirements, Title V Operating Permit requirements of the CAA and state regulatory counterparts contained within the Wisconsin SIP designed to implement the CAA. In 2013, WPL, along with the other owners of Edgewater and Columbia, entered into a Consent Decree with the EPA and the Sierra Club to resolve the claims relating to Edgewater, Columbia and Nelson Dewey, while admitting no liability. In 2013, the Consent Decree was approved by the Western Wisconsin Court, thereby resolving all claims against WPL. Under the Consent Decree, WPL is required to install the following environmental controls systems:
• | SCR system at Edgewater Unit 5 by May 1, 2013 (placed in service in 2012);
• | Scrubbers and baghouses at Columbia Units 1 and 2 by December 31, 2014 (placed in service in 2014);
• | Scrubber and baghouse at Edgewater Unit 5 by December 31, 2016; and
• | SCR system at Columbia Unit 2 by December 31, 2018.
WPL is also required to fuel switch or retire Edgewater Unit 4 by December 31, 2018. In December 2015, WPL retired Nelson Dewey Units 1 and 2 and Edgewater Unit 3 consistent with the Consent Decree. In addition, the Consent Decree establishes emission rate limits for SO2, NOx and particulate matter for Columbia Units 1 and 2, Nelson Dewey Units 1 and 2, and Edgewater Units 4 and 5. The Consent Decree also includes annual plant-wide emission caps for SO2 and NOx for Columbia, Edgewater and Nelson Dewey. In addition, WPL will complete approximately $7 million in environmental mitigation projects. Final recovery of the costs expected to be incurred related to the Consent Decree will be decided by the PSCW in future rate cases or other proceedings. Alliant Energy and WPL currently expect to recover any material costs incurred by WPL related to compliance with the terms of the Consent Decree from WPL’s electric customers. IPL Consent Decree - In July 2015, IPL entered into a Consent Decree with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa to resolve potential claims regarding CAA issues associated with emissions from IPL’s coal-fired generating facilities in Iowa, while admitting no liability. In September 2015, the Consent Decree was approved by the Northern Iowa Court, thereby resolving all potential claims against IPL. Under the Consent Decree, IPL is required to install the following environmental controls systems:
• | Scrubber and baghouse at the Ottumwa Generating Station by December 31, 2015 (placed in service in 2014);
• | Scrubber and baghouse at the Lansing Generating Station by December 31, 2016 (scrubber was placed in service in June 2015 and baghouse was placed in service in 2010); and
• | SCR system or equivalent NOx reduction system at the Ottumwa Generating Station by December 31, 2019.
IPL is also required to fuel switch or retire the following EGUs:
• | M.L. Kapp Generating Station by August 31, 2015 (switched the fuel type from coal to natural gas in June 2015);
• | Prairie Creek Unit 4 by June 1, 2018;
• | Burlington Generating Station by December 31, 2021; and
• | Prairie Creek Units 1 and 3 by December 31, 2025.
In addition, IPL is required to either install combined cycle technology at, or retire, the Dubuque and Sutherland Generation Stations by June 1, 2019. IPL previously switched the fuel type from coal to natural gas at these EGUs. The Consent Decree also establishes SO2, NOx and particulate matter emission rate limits with varying averaging times for the Burlington, Lansing, M.L. Kapp, Ottumwa and Prairie Creek Generating Stations. In addition, the Consent Decree includes calendar-year SO2 and NOx emission caps for the Prairie Creek Generating Station, and calendar-year SO2 and NOx emission caps in aggregate for the Burlington, Dubuque, Lansing, M.L. Kapp, Ottumwa, Prairie Creek and Sutherland Generating Stations. Pursuant to the Consent Decree, IPL paid a civil penalty of $1 million in 2015 and will complete approximately $6 million in environmental mitigation projects. Alliant Energy and IPL currently expect to recover all material costs incurred by IPL related to the environmental control systems and environmental mitigation projects from IPL’s electric customers. The recovery of such costs will be decided by IPL’s regulators in future rate cases or other proceedings. Alliant Energy and IPL currently do not expect to recover costs related to the civil penalty from IPL’s electric customers. Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however future capital investments and/or modifications to EGUs to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters are included below, along with a brief description of these environmental rules. Air Quality - CSAPR is an emissions trading program that requires SO2 and NOx emissions reductions at certain IPL and WPL fossil-fueled EGUs through installation of environmental controls and/or purchases of allowances. Compliance with emission limits began in 2015, with additional emission limits reductions beginning in 2017. Alliant Energy, IPL and WPL are currently in compliance with the Phase I CSAPR emission limits. Ozone NAAQS Rule may require NOx emission reductions in certain non-attainment areas designated by the EPA. The EPA’s final designations of non-attainment areas for this rule are currently expected to be issued by October 2017. Compliance deadlines range from 2020 through 2037 depending on the level of ozone monitored in non-attainment areas. Sheboygan County in Wisconsin is currently the only non-attainment area in Alliant Energy’s service territory. WPL operates Edgewater and Sheboygan Falls in Sheboygan County, Wisconsin. Clean Air Act Section 111(d) establishes standards under Section 111(d) of the CAA, otherwise referred to as the Clean Power Plan, for states to follow in developing plans to reduce CO2 emissions from existing fossil-fueled EGUs. The standards include an interim compliance period from 2022 through 2029 and a final compliance requirement beginning in 2030. In February 2016, the Supreme Court issued a stay of the Clean Power Plan until pending legal challenges are resolved, which places implementation of the final standards on hold indefinitely. Clean Air Act Section 111(b) establishes standards under Section 111(b) of the CAA for CO2 emissions limits for certain new fossil-fueled EGUs. Marshalltown and WPL’s proposed Riverside expansion are expected to be impacted by these standards. Marshalltown is being constructed, and WPL’s proposed Riverside expansion is being designed, to achieve compliance with these standards. Water Quality - Section 316(b) of the Federal Clean Water Act regulates cooling water intake structures and minimizes adverse environmental impacts to fish and other aquatic life. Compliance will be incorporated during periodic facility permit renewal cycles, with final compliance anticipated by 2022. Effluent Limitation Guidelines require changes to discharge limits for wastewater from steam generating facilities. Compliance for existing steam generating facilities will be required after November 1, 2018 but before December 31, 2023, depending on each facility’s wastewater permit renewal cycle, and immediately upon operation for new steam generating facilities constructed after January 2016. Hydroelectric Fish Passage Device - WPL is currently required to install an agency-approved fish passage device at its Prairie du Sac hydro plant by December 31, 2020. Land and Solid Waste - CCR Rule establishes minimum criteria for disposing of CCR in landfills and surface impoundments (ash ponds), and allows for continued operation of ash ponds if they meet certain performance criteria. (f) Credit Risk - IPL and WPL provide regulated electricity and natural gas services to residential, commercial, industrial and wholesale customers in the Midwest region of the U.S. The geographic concentration of these customers did not contribute significantly to overall credit risk exposure. In addition, as a result of a diverse customer base, IPL and WPL did not have any significant credit risk concentration for receivables arising from the sale of electricity or natural gas services. Alliant Energy, IPL and WPL are subject to credit risk related to the ability of counterparties to meet their contractual payment obligations or the potential non-performance of counterparties to deliver contracted commodities and other goods or services at the contracted price. IPL and WPL are typically net buyers of commodities (primarily electricity, coal and natural gas) required to provide regulated electricity and natural gas services to their customers. As a result, IPL and WPL are also subject to credit risk related to their counterparties’ failures to deliver commodities at the contracted price. Credit policies are maintained to mitigate credit risk. These credit policies include evaluation of the financial condition of certain counterparties, use of credit risk-related contingent provisions in certain commodity agreements that require credit support from counterparties that exceed certain exposure limits, diversification of counterparties to reduce concentrations of credit risk and the use of standardized agreements that facilitate the netting of cash flows associated with certain counterparties. IPL has a PPA that grants it rights to purchase capacity and the resulting energy from DAEC through December 31, 2025. This PPA exposes Alliant Energy and IPL to risk of counterparty non-performance. However, financial risk is mitigated by IPL’s fuel-related cost recovery mechanisms. Refer to Note 16(b) for further discussion of the DAEC PPA. Based on these credit policies, counterparty diversification and utility cost recovery mechanisms, it is unlikely that counterparty non-performance would have a material effect on financial condition or results of operations. However, there is no assurance that these items will protect against all losses from counterparty non-performance. Refer to Notes 5(a) and 15 for details of allowances for doubtful accounts and credit risk-related contingent features, respectively.
WPL [Member] |
Commitments And Contingencies | COMMITMENTS AND CONTINGENCIES (a) Capital Purchase Obligations - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects. IPL’s projects include generation maintenance and performance improvements for Marshalltown Combustion Turbine Units 1-3. WPL’s projects include the installation of a scrubber and baghouse at Edgewater Unit 5 to reduce SO2 and mercury emissions, generation maintenance and performance improvements at Columbia Units 1 and 2, and the installation of an SCR system at Columbia Unit 2 to reduce NOx emissions at the EGU. At December 31, 2015, Alliant Energy’s, IPL’s and WPL’s minimum future commitments related to certain contractual obligations for these projects were $23 million, $7 million and $16 million, respectively. (b) Operating Expense Purchase Obligations - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. Other operating expense purchase obligations with various vendors provide other goods and services. At December 31, 2015, minimum future commitments related to these operating expense purchase obligations were as follows (in millions):
Alliant Energy | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |  | Total
Purchased power (a): |  |  |  |  |  |  |  |  |  |  |  |  |
DAEC (IPL) (b) |  | $125 |  |  |  | $138 |  |  |  | $131 |  |  |  | $143 |  |  |  | $133 |  |  |  | $749 |  |  |  | $1,419 |
Other | 77 |  |  | 44 |  |  | 44 |  |  | — |  |  | — |  |  | — |  |  | 165 |
| 202 |  |  | 182 |  |  | 175 |  |  | 143 |  |  | 133 |  |  | 749 |  |  | 1,584 |
Natural gas | 173 |  |  | 82 |  |  | 52 |  |  | 43 |  |  | 32 |  |  | 16 |  |  | 398 |
Coal (c) | 129 |  |  | 76 |  |  | 50 |  |  | 12 |  |  | — |  |  | — |  |  | 267 |
SO2 emission allowances | 14 |  |  | 8 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 22 |
Other (d) | 6 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 2 |  |  | 7 |  |  | 21 |
|  | $524 |  |  |  | $350 |  |  |  | $279 |  |  |  | $200 |  |  |  | $167 |  |  |  | $772 |  |  |  | $2,292 |
IPL | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |  | Total
Purchased power (a): |  |  |  |  |  |  |  |  |  |  |  |  |
DAEC (b) |  | $125 |  |  |  | $138 |  |  |  | $131 |  |  |  | $143 |  |  |  | $133 |  |  |  | $749 |  |  |  | $1,419 |
Other | 1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 1 |
| 126 |  |  | 138 |  |  | 131 |  |  | 143 |  |  | 133 |  |  | 749 |  |  | 1,420 |
Natural gas | 95 |  |  | 42 |  |  | 35 |  |  | 28 |  |  | 18 |  |  | 10 |  |  | 228 |
Coal (c) | 70 |  |  | 30 |  |  | 17 |  |  | 4 |  |  | — |  |  | — |  |  | 121 |
SO2 emission allowances | 14 |  |  | 8 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 22 |
Other (d) | 1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 1 |
| $306 |  |  | $218 |  |  |  | $183 |  |  |  | $175 |  |  |  | $151 |  |  |  | $759 |  |  |  | $1,792 |
WPL | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |  | Total
Purchased power (a) |  | $76 |  |  |  | $44 |  |  |  | $44 |  |  |  | $— |  |  |  | $— |  |  |  | $— |  |  |  | $164 |
Natural gas | 78 |  |  | 40 |  |  | 17 |  |  | 15 |  |  | 14 |  |  | 6 |  |  | 170 |
Coal (c) | 59 |  |  | 46 |  |  | 33 |  |  | 8 |  |  | — |  |  | — |  |  | 146 |
Other (d) | 2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 2 |
|  | $215 |  |  |  | $130 |  |  |  | $94 |  |  |  | $23 |  |  |  | $14 |  |  |  | $6 |  |  |  | $482 |
(a) | Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. Refer to Note 18 for additional information on purchased power transactions.
(b) | Includes commitments incurred under a PPA, which grants IPL rights to purchase up to 431 MWs of capacity and the resulting energy from DAEC for a term through December 31, 2025. If energy delivered is less than the targeted energy amount, an adjustment payment will be made to IPL, which will be reflected in IPL’s fuel adjustment clause.
(c) | Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2015 regarding expected future usage, which is subject to change.
(d) | Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2015.
Certain contracts are considered leases and are therefore not included here, but are included in Note 10. (c) Legal Proceedings - Flood Damage Claims - In 2013, several plaintiffs purporting to represent a class of residential and commercial property owners filed a complaint against CRANDIC, Alliant Energy and various other defendants in the Iowa District Court for Linn County. Plaintiffs assert claims of negligence and strict liability based on their allegations that CRANDIC (along with other defendants) caused or exacerbated flooding of the Cedar River in June 2008. On February 12, 2016, the Iowa District Court for Linn County ruled in favor of Alliant Energy and CRANDIC and dismissed all claims against them, resulting in no loss. Plaintiffs have 30 days to seek an appeal of this decision. Other - Alliant Energy, IPL and WPL are involved in other legal and administrative proceedings before various courts and agencies with respect to matters arising in the ordinary course of business. Although unable to predict the outcome of these matters, Alliant Energy, IPL and WPL believe that appropriate reserves have been established and final disposition of these actions will not have a material effect on their financial condition or results of operations. (e) Environmental Matters - Alliant Energy, IPL and WPL are subject to environmental regulations as a result of their current and past operations. These regulations are designed to protect public health and the environment and have resulted in compliance, remediation, containment and monitoring obligations, which are recorded as environmental liabilities. At December 31, current environmental liabilities were included in “Other current liabilities” and non-current environmental liabilities were included in “Other liabilities” on the balance sheets as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
Current environmental liabilities |  | $2.7 |  |  |  | $2.0 |  |  |  | $1.7 |  |  |  | $1.7 |  |  |  | $1.0 |  |  |  | $0.3 |
Non-current environmental liabilities | 12.8 |  |  | 13.5 |  |  | 11.2 |  |  | 11.9 |  |  | 1.5 |  |  | 1.6 |
|  | $15.5 |  |  |  | $15.5 |  |  |  | $12.9 |  |  |  | $13.6 |  |  |  | $2.5 |  |  |  | $1.9 |
MGP Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. IPL and WPL are currently monitoring and/or remediating 24 and 5 sites, respectively. Environmental liabilities related to these MGP sites are recorded based upon periodic studies. Such amounts are based on the best current estimate of the remaining amount to be incurred for investigation, remediation and monitoring costs for those sites where the investigation process has been or is substantially completed, and the minimum of the estimated cost range for those sites where the investigation is in its earlier stages. There are inherent uncertainties associated with the estimated remaining costs for MGP projects primarily due to unknown site conditions and potential changes in regulatory agency requirements. It is possible that future cost estimates will be greater than current estimates as the investigation process proceeds and as additional facts become known. The amounts recognized as liabilities are reduced for expenditures incurred and are adjusted as further information develops or circumstances change. Costs of future expenditures for environmental remediation obligations are not discounted. At December 31, 2015, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Range of estimated future costs |  | $11 |  | - | $28 |  |  | $9 |  | - | $25 |  |  | $2 |  | - | $3
Current and non-current environmental liabilities | 15 |  | 13 |  | 2
Refer to Note 2 for discussion of regulatory assets recorded by IPL and WPL, which reflect the probable future rate recovery of MGP expenditures. Considering the current rate treatment, and assuming no material change therein, Alliant Energy, IPL and WPL believe that the clean-up costs incurred for these MGP sites will not have a material effect on their financial condition or results of operations. WPL Consent Decree - In 2009, the EPA sent a notice of violation to WPL as an owner and the operator of Edgewater, Nelson Dewey and Columbia alleging that the owners of such EGUs failed to comply with appropriate pre-construction review and permitting requirements and as a result violated the PSD program requirements, Title V Operating Permit requirements of the CAA and the Wisconsin SIP. In 2010, the Sierra Club filed complaints against WPL, as owner and operator of Nelson Dewey and Columbia, and separately as owner and operator of Edgewater, based on allegations that modifications were made at the facilities without complying with the PSD program requirements, Title V Operating Permit requirements of the CAA and state regulatory counterparts contained within the Wisconsin SIP designed to implement the CAA. In 2013, WPL, along with the other owners of Edgewater and Columbia, entered into a Consent Decree with the EPA and the Sierra Club to resolve the claims relating to Edgewater, Columbia and Nelson Dewey, while admitting no liability. In 2013, the Consent Decree was approved by the Western Wisconsin Court, thereby resolving all claims against WPL. Under the Consent Decree, WPL is required to install the following environmental controls systems:
• | SCR system at Edgewater Unit 5 by May 1, 2013 (placed in service in 2012);
• | Scrubbers and baghouses at Columbia Units 1 and 2 by December 31, 2014 (placed in service in 2014);
• | Scrubber and baghouse at Edgewater Unit 5 by December 31, 2016; and
• | SCR system at Columbia Unit 2 by December 31, 2018.
WPL is also required to fuel switch or retire Edgewater Unit 4 by December 31, 2018. In December 2015, WPL retired Nelson Dewey Units 1 and 2 and Edgewater Unit 3 consistent with the Consent Decree. In addition, the Consent Decree establishes emission rate limits for SO2, NOx and particulate matter for Columbia Units 1 and 2, Nelson Dewey Units 1 and 2, and Edgewater Units 4 and 5. The Consent Decree also includes annual plant-wide emission caps for SO2 and NOx for Columbia, Edgewater and Nelson Dewey. In addition, WPL will complete approximately $7 million in environmental mitigation projects. Final recovery of the costs expected to be incurred related to the Consent Decree will be decided by the PSCW in future rate cases or other proceedings. Alliant Energy and WPL currently expect to recover any material costs incurred by WPL related to compliance with the terms of the Consent Decree from WPL’s electric customers. IPL Consent Decree - In July 2015, IPL entered into a Consent Decree with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa to resolve potential claims regarding CAA issues associated with emissions from IPL’s coal-fired generating facilities in Iowa, while admitting no liability. In September 2015, the Consent Decree was approved by the Northern Iowa Court, thereby resolving all potential claims against IPL. Under the Consent Decree, IPL is required to install the following environmental controls systems:
• | Scrubber and baghouse at the Ottumwa Generating Station by December 31, 2015 (placed in service in 2014);
• | Scrubber and baghouse at the Lansing Generating Station by December 31, 2016 (scrubber was placed in service in June 2015 and baghouse was placed in service in 2010); and
• | SCR system or equivalent NOx reduction system at the Ottumwa Generating Station by December 31, 2019.
IPL is also required to fuel switch or retire the following EGUs:
• | M.L. Kapp Generating Station by August 31, 2015 (switched the fuel type from coal to natural gas in June 2015);
• | Prairie Creek Unit 4 by June 1, 2018;
• | Burlington Generating Station by December 31, 2021; and
• | Prairie Creek Units 1 and 3 by December 31, 2025.
In addition, IPL is required to either install combined cycle technology at, or retire, the Dubuque and Sutherland Generation Stations by June 1, 2019. IPL previously switched the fuel type from coal to natural gas at these EGUs. The Consent Decree also establishes SO2, NOx and particulate matter emission rate limits with varying averaging times for the Burlington, Lansing, M.L. Kapp, Ottumwa and Prairie Creek Generating Stations. In addition, the Consent Decree includes calendar-year SO2 and NOx emission caps for the Prairie Creek Generating Station, and calendar-year SO2 and NOx emission caps in aggregate for the Burlington, Dubuque, Lansing, M.L. Kapp, Ottumwa, Prairie Creek and Sutherland Generating Stations. Pursuant to the Consent Decree, IPL paid a civil penalty of $1 million in 2015 and will complete approximately $6 million in environmental mitigation projects. Alliant Energy and IPL currently expect to recover all material costs incurred by IPL related to the environmental control systems and environmental mitigation projects from IPL’s electric customers. The recovery of such costs will be decided by IPL’s regulators in future rate cases or other proceedings. Alliant Energy and IPL currently do not expect to recover costs related to the civil penalty from IPL’s electric customers. Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however future capital investments and/or modifications to EGUs to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters are included below, along with a brief description of these environmental rules. Air Quality - CSAPR is an emissions trading program that requires SO2 and NOx emissions reductions at certain IPL and WPL fossil-fueled EGUs through installation of environmental controls and/or purchases of allowances. Compliance with emission limits began in 2015, with additional emission limits reductions beginning in 2017. Alliant Energy, IPL and WPL are currently in compliance with the Phase I CSAPR emission limits. Ozone NAAQS Rule may require NOx emission reductions in certain non-attainment areas designated by the EPA. The EPA’s final designations of non-attainment areas for this rule are currently expected to be issued by October 2017. Compliance deadlines range from 2020 through 2037 depending on the level of ozone monitored in non-attainment areas. Sheboygan County in Wisconsin is currently the only non-attainment area in Alliant Energy’s service territory. WPL operates Edgewater and Sheboygan Falls in Sheboygan County, Wisconsin. Clean Air Act Section 111(d) establishes standards under Section 111(d) of the CAA, otherwise referred to as the Clean Power Plan, for states to follow in developing plans to reduce CO2 emissions from existing fossil-fueled EGUs. The standards include an interim compliance period from 2022 through 2029 and a final compliance requirement beginning in 2030. In February 2016, the Supreme Court issued a stay of the Clean Power Plan until pending legal challenges are resolved, which places implementation of the final standards on hold indefinitely. Clean Air Act Section 111(b) establishes standards under Section 111(b) of the CAA for CO2 emissions limits for certain new fossil-fueled EGUs. Marshalltown and WPL’s proposed Riverside expansion are expected to be impacted by these standards. Marshalltown is being constructed, and WPL’s proposed Riverside expansion is being designed, to achieve compliance with these standards. Water Quality - Section 316(b) of the Federal Clean Water Act regulates cooling water intake structures and minimizes adverse environmental impacts to fish and other aquatic life. Compliance will be incorporated during periodic facility permit renewal cycles, with final compliance anticipated by 2022. Effluent Limitation Guidelines require changes to discharge limits for wastewater from steam generating facilities. Compliance for existing steam generating facilities will be required after November 1, 2018 but before December 31, 2023, depending on each facility’s wastewater permit renewal cycle, and immediately upon operation for new steam generating facilities constructed after January 2016. Hydroelectric Fish Passage Device - WPL is currently required to install an agency-approved fish passage device at its Prairie du Sac hydro plant by December 31, 2020. Land and Solid Waste - CCR Rule establishes minimum criteria for disposing of CCR in landfills and surface impoundments (ash ponds), and allows for continued operation of ash ponds if they meet certain performance criteria. (f) Credit Risk - IPL and WPL provide regulated electricity and natural gas services to residential, commercial, industrial and wholesale customers in the Midwest region of the U.S. The geographic concentration of these customers did not contribute significantly to overall credit risk exposure. In addition, as a result of a diverse customer base, IPL and WPL did not have any significant credit risk concentration for receivables arising from the sale of electricity or natural gas services. Alliant Energy, IPL and WPL are subject to credit risk related to the ability of counterparties to meet their contractual payment obligations or the potential non-performance of counterparties to deliver contracted commodities and other goods or services at the contracted price. IPL and WPL are typically net buyers of commodities (primarily electricity, coal and natural gas) required to provide regulated electricity and natural gas services to their customers. As a result, IPL and WPL are also subject to credit risk related to their counterparties’ failures to deliver commodities at the contracted price. Credit policies are maintained to mitigate credit risk. These credit policies include evaluation of the financial condition of certain counterparties, use of credit risk-related contingent provisions in certain commodity agreements that require credit support from counterparties that exceed certain exposure limits, diversification of counterparties to reduce concentrations of credit risk and the use of standardized agreements that facilitate the netting of cash flows associated with certain counterparties. IPL has a PPA that grants it rights to purchase capacity and the resulting energy from DAEC through December 31, 2025. This PPA exposes Alliant Energy and IPL to risk of counterparty non-performance. However, financial risk is mitigated by IPL’s fuel-related cost recovery mechanisms. Refer to Note 16(b) for further discussion of the DAEC PPA. Based on these credit policies, counterparty diversification and utility cost recovery mechanisms, it is unlikely that counterparty non-performance would have a material effect on financial condition or results of operations. However, there is no assurance that these items will protect against all losses from counterparty non-performance. Refer to Notes 5(a) and 15 for details of allowances for doubtful accounts and credit risk-related contingent features, respectively.

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