Algonquin Power & Utilities Corp. – Consolidated Financial Statements ALGONQUIN POWER & UTILITIES CORP.  Notes to the Consolidated Financial Statements  December 31, 2012 and 2011   (in thousands of Canadian dollars except as noted and amounts per share)  5.  Property, plant and equipment (continued)  6. Intangible assets In 2012, APCo wrote down its investment in a small hydro facility and recognized an impairment  charge on property, plant and equipment of $253 (2011 - $1,370) representing the difference  between the carrying value of the assets and their estimated fair value. The fair value of the  facilities was estimated based on prior transactions involving sales of comparable facilities and  management’s best estimates. In December 2011, Liberty Utilities wrote down $1,058 from facilities` assets based on regulatory  decisions in 2011 that these costs are not capitalizable for rate-base purposes. Intangible assets consist of the following:  2012 Cost Accumulated amortization  Net book  value  Power sales contracts $ 60,435  $ 24,881  $ 35,554  Customer relationships  26,674 5,447 21,227 $ 87,109  $ 30,328  $ 56,781  2011 Cost Accumulated amortization  Net book  value  Power sales contracts $ 52,073  $ 19,123  $ 32,950  Customer relationships  27,206 4,887 22,319 $ 79,279  $ 24,010  $ 55,269  The Region of Peel elected not to extend the existing waste processing contract with the  Company. As a result, the remaining intangible assets associated with the existing waste  management and energy contracts of the facility were written off in 2011 and the Company  recognized a charge on intangible assets of $13,430.  Estimated amortization expense for intangibles for the next four years is $4,200 each year and  $2,450 in year five. 2012 Annual Report 99