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Asset Retirement Obligations
12 Months Ended
Dec. 31, 2011
Asset Retirement Obligation Disclosure [Abstract]  
Asset Retirement Obligations
Asset Retirement Obligations
The ARO is recorded based on the determination of underlying assumptions, such as the Company’s discount rate, estimates of the future costs for decommissioning, and the timing of the removal activities to be performed. Any changes in these assumptions underlying the required calculations may require revisions to the estimated ARO when identified. A reconciliation of ARO is as follows:
 
 
PNMR
 
PNM
 
TNMP
 
(In thousands)
Liability at December 31, 2008(1)
$
63,675

 
$
62,879

 
$
711

Liabilities incurred
3,464

 
3,464

 

Liabilities settled
(8
)
 
(8
)
 

Accretion expense
5,751

 
5,683

 
60

Revisions to estimated cash flows (2)
(1,919
)
 
(1,919
)
 

Liability at December 31, 2009
70,963

 
70,099

 
771

Liabilities incurred
532

 
531

 

Liabilities settled
(603
)
 
(413
)
 
(190
)
Accretion expense
6,019

 
5,945

 
67

Revisions to estimated cash flows (2)
(274
)
 
(274
)
 

Liability at December 31, 2010
76,637

 
75,888

 
648

Liabilities incurred
60

 
60

 

Liabilities settled
(4
)
 

 
(4
)
Accretion expense
6,114

 
6,051

 
55

Revisions to estimated cash flows (2)
(3,574
)
 
(3,574
)
 

Liability at December 31, 2011
$
79,233

 
$
78,425

 
$
699

 
(1) 
ARO for PNMR and PNM includes $0.2 million at December 31, 2008 for PNM Gas.
(2) 
Based on studies to estimate amount and timing of future ARO expenditures. PNM has an ARO for PVNGS that includes the obligations for nuclear decommissioning of that facility. In 2011, a new decommissioning study for PVNGS reflects updated cash flow estimates and the 20-year license extension, which extends the commencement of decommissioning to 2045. The new study resulted in a $4.2 million decrease to the ARO.