during 2016 and 2015 , wpz received net proceeds of approximately $ 115 million and approximately $ 59 million , respectively , from equity issued under this registration . distributions from equity-method investees the organizational documents of entities in which we have an equity-method investment generally require distribution of their available cash to their members on a quarterly basis . in each case , available cash is reduced , in part , by reserves appropriate for operating their respective businesses . ( see note 6 – investing activities of notes to consolidated financial statements for our more significant equity-method investees . ) 70 credit ratings our ability to borrow money is impacted by our credit ratings and the credit ratings of wpz . the current ratings are as follows : rating agency outlook senior unsecured debt rating corporate credit rating wmb : s & p global ratings stable bb bb moody 's investors service stable ba2 n/a fitch ratings stable bb+ n/a wpz : s & p global ratings stable bbb- bbb- moody 's investors service stable baa3 n/a fitch ratings stable bbb- n/a considering our credit ratings as of december 31 , 2016 , we estimate that we could be required to provide up to $ 36 million in additional collateral of either cash or letters of credit with third parties under existing contracts . at the present time , we have not provided any additional collateral to third parties but no assurance can be given that we will not be requested to provide collateral in the future . as of december 31 , 2016 , we estimate that a downgrade to a rating below investment-grade for wpz could require it to provide up to $ 376 million in additional collateral of either cash or letters of credit with third parties under existing contracts . 71 sources ( uses ) of cash the following table summarizes the sources ( uses ) of cash and cash equivalents for each of the periods presented ( see notes to consolidated financial statements for the notes referenced in the table ) : replace_table_token_16_th operating activities the factors that determine operating activities are largely the same as those that affect net income ( loss ) , with the exception of noncash items such as depreciation and amortization , provision ( benefit ) for deferred income taxes , impairment of goodwill , impairment of equity-method investments , impairment of and net ( gain ) loss on sale of assets and businesses , and gain on remeasurement of equity-method investment . our net cash provided ( used ) by operating activities in 2016 increased from 2015 primarily due to the impact of net favorable changes in operating working capital and receipts from contract restructurings . our net cash provided ( used ) by operating activities in 2015 increased from 2014 primarily due to the impact of net favorable changes in operating working capital and the absence of contributions from acmp for the first six months of 2014 . 72 off-balance sheet arrangements and guarantees of debt or other commitments we have various other guarantees and commitments which are disclosed in note 4 – variable interest entities , note 11 – property , plant , and equipment , note 14 – debt , banking arrangements , and leases , note 17 – fair value measurements , guarantees , and concentration of credit risk , and note 18 – contingent liabilities and commitments of notes to consolidated financial statements . we do not believe these guarantees and commitments or the possible fulfillment of them will prevent us from meeting our liquidity needs . contractual obligations the table below summarizes the maturity dates of our contractual obligations at december 31 , 2016 : replace_table_token_17_th ( 1 ) includes the borrowings outstanding under credit facilities , but does not include any related variable-rate interest payments . ( 2 ) includes $ 750 million of 6.125 percent senior notes due 2022 that wpz intends to redeem on february 23 , 2017 and related interest , presented in the table above according to the original contractual terms . ( 3 ) includes approximately $ 244 million in open property , plant , and equipment purchase orders . includes an estimated $ 418 million long-term ethane purchase obligation with index-based pricing terms that is reflected in this table at december 31 , 2016 prices . this obligation is part of an overall exchange agreement whereby volumes we transport on oppl are sold at a third-party fractionator near conway , kansas , and we are subsequently obligated to purchase ethane volumes at mont belvieu . the purchased ethane volumes may be utilized or resold at comparable prices in the mont belvieu market . includes an estimated $ 619 million long-term ethane purchase obligation with index-based pricing terms that primarily supplies third parties at their plants and is valued in this table at a price calculated using december 31 , 2016 prices . any excess purchased volumes may be sold at comparable market prices . includes an estimated $ 586 million long-term mixed ngls purchase obligation with index-based pricing terms that is reflected in this table at december 31 , 2016 prices . in addition , we have not included certain natural gas life-of-lease contracts for which the future volumes are indeterminable . we have not included commitments , beyond purchase orders , for the acquisition or construction of property , plant , and equipment or expected contributions to our jointly owned investments . ( see company outlook — expansion projects . ) ( 4 ) does not include estimated contributions to our pension and other postretirement benefit plans . we made contributions to our pension and other postretirement benefit plans of $ 72 million in 2016 and $ 70 million in 2015 . story_separator_special_tag in 2017 , we expect to contribute approximately $ 69 million to these plans ( see note 10 – employee benefit plans of notes to consolidated financial statements ) . tax-qualified pension plans are required to meet minimum contribution requirements . in the past , we have contributed amounts to our tax-qualified pension plans in excess of the minimum required contribution . these excess amounts can be used to offset future minimum contribution requirements . during 2016 , we contributed $ 60 million to our tax-qualified pension plans . in addition to these contributions , a portion of the excess contributions was used to meet the minimum contribution requirements . during 2017 , we expect to contribute approximately $ 60 million to our tax-qualified pension plans and use excess amounts to satisfy minimum contribution requirements , if needed . additionally , estimated future minimum funding requirements may vary significantly from historical requirements if actual results differ significantly from estimated 73 results for assumptions such as returns on plan assets , interest rates , retirement rates , mortality , and other significant assumptions or by changes to current legislation and regulations . ( 5 ) we have not included income tax liabilities in the table above . see note 8 – provision ( benefit ) for income taxes of notes to consolidated financial statements for a discussion of income taxes , including our contingent tax liability reserves . effects of inflation our operations have historically not been materially affected by inflation . approximately 39 percent of our gross property , plant , and equipment is comprised of our interstate natural gas pipeline assets . they are subject to regulation , which limits recovery to historical cost . while amounts in excess of historical cost are not recoverable under current ferc practices , we anticipate being allowed to recover and earn a return based on increased actual cost incurred to replace existing assets . cost-based regulations , along with competition and other market factors , may limit our ability to recover such increased costs . for our gathering and processing assets , operating costs are influenced to a greater extent by both competition for specialized services and specific price changes in crude oil and natural gas and related commodities than by changes in general inflation . crude oil , natural gas , and ngl prices are particularly sensitive to the market perceptions concerning the supply and demand balance in the near future , as well as general economic conditions . however , our exposure to certain of these price changes is reduced through the fee-based nature of certain of our services and the use of hedging instruments . environmental we are a participant in certain environmental activities in various stages including assessment studies , cleanup operations , and or remedial processes at certain sites , some of which we currently do not own ( see note 18 – contingent liabilities and commitments of notes to consolidated financial statements ) . we are monitoring these sites in a coordinated effort with other potentially responsible parties , the epa , or other governmental authorities . we are jointly and severally liable along with unrelated third parties in some of these activities and solely responsible in others . current estimates of the most likely costs of such activities are approximately $ 38 million , all of which are included in accrued liabilities and regulatory liabilities , deferred income , and other on the consolidated balance sheet at december 31 , 2016 . we will seek recovery of approximately $ 9 million of these accrued costs through future natural gas transmission rates . the remainder of these costs will be funded from operations . during 2016 , we paid approximately $ 6 million for cleanup and or remediation and monitoring activities . we expect to pay approximately $ 9 million in 2017 for these activities . estimates of the most likely costs of cleanup are generally based on completed assessment studies , preliminary results of studies , or our experience with other similar cleanup operations . at december 31 , 2016 , certain assessment studies were still in process for which the ultimate outcome may yield different estimates of most likely costs . therefore , the actual costs incurred will depend on the final amount , type , and extent of contamination discovered at these sites , the final cleanup standards mandated by the epa or other governmental authorities , and other factors . in march 2008 , the epa promulgated a new , lower national ambient air quality standard ( naaqs ) for ground-level ozone . in may 2012 , the epa completed designation of new eight-hour ozone nonattainment areas . several transco facilities are located in 2008 ozone nonattainment areas . in december 2014 , the epa proposed to further reduce the ground-level ozone naaqs from the march 2008 levels and subsequently finalized a rule on october 1 , 2015. we are monitoring the rule 's implementation as the reduction will trigger additional federal and state regulatory actions that may impact our operations . to date , no federal actions have been proposed to mandate additional emission controls at these facilities . pursuant to recently finalized state regulatory actions associated with implementation of the 2008 ozone standard , we anticipate that some facilities may be subject to increased controls within five years . implementation of the regulations is expected to result in impacts to our operations and increase the cost of additions to property , plant , and equipment – net on the consolidated balance sheet for both new and existing facilities in affected areas . we are unable at this time to estimate with any certainty the cost of additions that may be required to meet the regulations . on january 22 , 2010 , the epa set a new one-hour nitrogen dioxide ( no 2 ) naaqs . the effective date of the new no 2 standard was april 12 , 2010.

liquidity based on our forecasted levels of cash flow from operations and other sources of liquidity , we expect to have sufficient liquidity to manage our businesses in 2017. our internal and external sources of consolidated liquidity to fund working capital requirements , capital and investment expenditures , debt service payments , dividends and distributions , and tax payments include : cash and cash equivalents on hand ; cash generated from operations ; distributions from wpz ; distributions from our equity-method investees based on our level of ownership ; 68 use of our credit facility ; cash proceeds from issuances of debt and or equity securities . wpz is expected to fund its cash needs through its cash flows from operations and its credit facility and or commercial paper program , as well as proceeds from planned asset monetizations as previously mentioned . wpz also established a distribution reinvestment program ( drip ) in the third quarter of 2016. we previously announced that we intended to reinvest approximately $ 1.2 billion into wpz in 2017 via the drip , funded primarily by our reduced quarterly cash dividend which would have allowed us to annually retain approximately $ 1.3 billion for reinvestment . as part of the financial repositioning announced in january 2017 , we discontinued our participation in the drip and expect to increase our regular quarterly cash dividend to $ 0.30 for the dividend to be paid in march 2017 . ( see note 1 – general , description of business , basis of presentation , and summary of significant accounting policies of notes to consolidated financial statements . ) we anticipate our more significant uses of cash to be : working capital requirements ; maintenance and expansion capital and investment expenditures ; interest on our long-term debt ; repayment of current debt maturities , and additional reductions in wpz 's debt with funds received as part of the financial repositioning ; investment in wpz as part of the financial repositioning ( see note 15 – stockholders ' equity of notes to consolidated financial statements ) ; quarterly dividends to our shareholders . potential risks associated with our planned levels of liquidity discussed above include those previously discussed in company outlook .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```liquidity based on our forecasted levels of cash flow from operations and other sources of liquidity , we expect to have sufficient liquidity to manage our businesses in 2017. our internal and external sources of consolidated liquidity to fund working capital requirements , capital and investment expenditures , debt service payments , dividends and distributions , and tax payments include : cash and cash equivalents on hand ; cash generated from operations ; distributions from wpz ; distributions from our equity-method investees based on our level of ownership ; 68 use of our credit facility ; cash proceeds from issuances of debt and or equity securities . wpz is expected to fund its cash needs through its cash flows from operations and its credit facility and or commercial paper program , as well as proceeds from planned asset monetizations as previously mentioned . wpz also established a distribution reinvestment program ( drip ) in the third quarter of 2016. we previously announced that we intended to reinvest approximately $ 1.2 billion into wpz in 2017 via the drip , funded primarily by our reduced quarterly cash dividend which would have allowed us to annually retain approximately $ 1.3 billion for reinvestment . as part of the financial repositioning announced in january 2017 , we discontinued our participation in the drip and expect to increase our regular quarterly cash dividend to $ 0.30 for the dividend to be paid in march 2017 . ( see note 1 – general , description of business , basis of presentation , and summary of significant accounting policies of notes to consolidated financial statements . ) we anticipate our more significant uses of cash to be : working capital requirements ; maintenance and expansion capital and investment expenditures ; interest on our long-term debt ; repayment of current debt maturities , and additional reductions in wpz 's debt with funds received as part of the financial repositioning ; investment in wpz as part of the financial repositioning ( see note 15 – stockholders ' equity of notes to consolidated financial statements ) ; quarterly dividends to our shareholders . potential risks associated with our planned levels of liquidity discussed above include those previously discussed in company outlook .
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 Suspicious Activity Report : during 2016 and 2015 , wpz received net proceeds of approximately $ 115 million and approximately $ 59 million , respectively , from equity issued under this registration . distributions from equity-method investees the organizational documents of entities in which we have an equity-method investment generally require distribution of their available cash to their members on a quarterly basis . in each case , available cash is reduced , in part , by reserves appropriate for operating their respective businesses . ( see note 6 – investing activities of notes to consolidated financial statements for our more significant equity-method investees . ) 70 credit ratings our ability to borrow money is impacted by our credit ratings and the credit ratings of wpz . the current ratings are as follows : rating agency outlook senior unsecured debt rating corporate credit rating wmb : s & p global ratings stable bb bb moody 's investors service stable ba2 n/a fitch ratings stable bb+ n/a wpz : s & p global ratings stable bbb- bbb- moody 's investors service stable baa3 n/a fitch ratings stable bbb- n/a considering our credit ratings as of december 31 , 2016 , we estimate that we could be required to provide up to $ 36 million in additional collateral of either cash or letters of credit with third parties under existing contracts . at the present time , we have not provided any additional collateral to third parties but no assurance can be given that we will not be requested to provide collateral in the future . as of december 31 , 2016 , we estimate that a downgrade to a rating below investment-grade for wpz could require it to provide up to $ 376 million in additional collateral of either cash or letters of credit with third parties under existing contracts . 71 sources ( uses ) of cash the following table summarizes the sources ( uses ) of cash and cash equivalents for each of the periods presented ( see notes to consolidated financial statements for the notes referenced in the table ) : replace_table_token_16_th operating activities the factors that determine operating activities are largely the same as those that affect net income ( loss ) , with the exception of noncash items such as depreciation and amortization , provision ( benefit ) for deferred income taxes , impairment of goodwill , impairment of equity-method investments , impairment of and net ( gain ) loss on sale of assets and businesses , and gain on remeasurement of equity-method investment . our net cash provided ( used ) by operating activities in 2016 increased from 2015 primarily due to the impact of net favorable changes in operating working capital and receipts from contract restructurings . our net cash provided ( used ) by operating activities in 2015 increased from 2014 primarily due to the impact of net favorable changes in operating working capital and the absence of contributions from acmp for the first six months of 2014 . 72 off-balance sheet arrangements and guarantees of debt or other commitments we have various other guarantees and commitments which are disclosed in note 4 – variable interest entities , note 11 – property , plant , and equipment , note 14 – debt , banking arrangements , and leases , note 17 – fair value measurements , guarantees , and concentration of credit risk , and note 18 – contingent liabilities and commitments of notes to consolidated financial statements . we do not believe these guarantees and commitments or the possible fulfillment of them will prevent us from meeting our liquidity needs . contractual obligations the table below summarizes the maturity dates of our contractual obligations at december 31 , 2016 : replace_table_token_17_th ( 1 ) includes the borrowings outstanding under credit facilities , but does not include any related variable-rate interest payments . ( 2 ) includes $ 750 million of 6.125 percent senior notes due 2022 that wpz intends to redeem on february 23 , 2017 and related interest , presented in the table above according to the original contractual terms . ( 3 ) includes approximately $ 244 million in open property , plant , and equipment purchase orders . includes an estimated $ 418 million long-term ethane purchase obligation with index-based pricing terms that is reflected in this table at december 31 , 2016 prices . this obligation is part of an overall exchange agreement whereby volumes we transport on oppl are sold at a third-party fractionator near conway , kansas , and we are subsequently obligated to purchase ethane volumes at mont belvieu . the purchased ethane volumes may be utilized or resold at comparable prices in the mont belvieu market . includes an estimated $ 619 million long-term ethane purchase obligation with index-based pricing terms that primarily supplies third parties at their plants and is valued in this table at a price calculated using december 31 , 2016 prices . any excess purchased volumes may be sold at comparable market prices . includes an estimated $ 586 million long-term mixed ngls purchase obligation with index-based pricing terms that is reflected in this table at december 31 , 2016 prices . in addition , we have not included certain natural gas life-of-lease contracts for which the future volumes are indeterminable . we have not included commitments , beyond purchase orders , for the acquisition or construction of property , plant , and equipment or expected contributions to our jointly owned investments . ( see company outlook — expansion projects . ) ( 4 ) does not include estimated contributions to our pension and other postretirement benefit plans . we made contributions to our pension and other postretirement benefit plans of $ 72 million in 2016 and $ 70 million in 2015 . story_separator_special_tag in 2017 , we expect to contribute approximately $ 69 million to these plans ( see note 10 – employee benefit plans of notes to consolidated financial statements ) . tax-qualified pension plans are required to meet minimum contribution requirements . in the past , we have contributed amounts to our tax-qualified pension plans in excess of the minimum required contribution . these excess amounts can be used to offset future minimum contribution requirements . during 2016 , we contributed $ 60 million to our tax-qualified pension plans . in addition to these contributions , a portion of the excess contributions was used to meet the minimum contribution requirements . during 2017 , we expect to contribute approximately $ 60 million to our tax-qualified pension plans and use excess amounts to satisfy minimum contribution requirements , if needed . additionally , estimated future minimum funding requirements may vary significantly from historical requirements if actual results differ significantly from estimated 73 results for assumptions such as returns on plan assets , interest rates , retirement rates , mortality , and other significant assumptions or by changes to current legislation and regulations . ( 5 ) we have not included income tax liabilities in the table above . see note 8 – provision ( benefit ) for income taxes of notes to consolidated financial statements for a discussion of income taxes , including our contingent tax liability reserves . effects of inflation our operations have historically not been materially affected by inflation . approximately 39 percent of our gross property , plant , and equipment is comprised of our interstate natural gas pipeline assets . they are subject to regulation , which limits recovery to historical cost . while amounts in excess of historical cost are not recoverable under current ferc practices , we anticipate being allowed to recover and earn a return based on increased actual cost incurred to replace existing assets . cost-based regulations , along with competition and other market factors , may limit our ability to recover such increased costs . for our gathering and processing assets , operating costs are influenced to a greater extent by both competition for specialized services and specific price changes in crude oil and natural gas and related commodities than by changes in general inflation . crude oil , natural gas , and ngl prices are particularly sensitive to the market perceptions concerning the supply and demand balance in the near future , as well as general economic conditions . however , our exposure to certain of these price changes is reduced through the fee-based nature of certain of our services and the use of hedging instruments . environmental we are a participant in certain environmental activities in various stages including assessment studies , cleanup operations , and or remedial processes at certain sites , some of which we currently do not own ( see note 18 – contingent liabilities and commitments of notes to consolidated financial statements ) . we are monitoring these sites in a coordinated effort with other potentially responsible parties , the epa , or other governmental authorities . we are jointly and severally liable along with unrelated third parties in some of these activities and solely responsible in others . current estimates of the most likely costs of such activities are approximately $ 38 million , all of which are included in accrued liabilities and regulatory liabilities , deferred income , and other on the consolidated balance sheet at december 31 , 2016 . we will seek recovery of approximately $ 9 million of these accrued costs through future natural gas transmission rates . the remainder of these costs will be funded from operations . during 2016 , we paid approximately $ 6 million for cleanup and or remediation and monitoring activities . we expect to pay approximately $ 9 million in 2017 for these activities . estimates of the most likely costs of cleanup are generally based on completed assessment studies , preliminary results of studies , or our experience with other similar cleanup operations . at december 31 , 2016 , certain assessment studies were still in process for which the ultimate outcome may yield different estimates of most likely costs . therefore , the actual costs incurred will depend on the final amount , type , and extent of contamination discovered at these sites , the final cleanup standards mandated by the epa or other governmental authorities , and other factors . in march 2008 , the epa promulgated a new , lower national ambient air quality standard ( naaqs ) for ground-level ozone . in may 2012 , the epa completed designation of new eight-hour ozone nonattainment areas . several transco facilities are located in 2008 ozone nonattainment areas . in december 2014 , the epa proposed to further reduce the ground-level ozone naaqs from the march 2008 levels and subsequently finalized a rule on october 1 , 2015. we are monitoring the rule 's implementation as the reduction will trigger additional federal and state regulatory actions that may impact our operations . to date , no federal actions have been proposed to mandate additional emission controls at these facilities . pursuant to recently finalized state regulatory actions associated with implementation of the 2008 ozone standard , we anticipate that some facilities may be subject to increased controls within five years . implementation of the regulations is expected to result in impacts to our operations and increase the cost of additions to property , plant , and equipment – net on the consolidated balance sheet for both new and existing facilities in affected areas . we are unable at this time to estimate with any certainty the cost of additions that may be required to meet the regulations . on january 22 , 2010 , the epa set a new one-hour nitrogen dioxide ( no 2 ) naaqs . the effective date of the new no 2 standard was april 12 , 2010.

