Currently we operate exclusively in the United States. We are committed to rigorously managing our balance sheet and financial risks. Given this development, we fully impaired our investment in New Brunswick in 2016. For the year ended December 31, 2020, one purchaser accounted for 10% of our revenues. No other purchasers accounted for greater than 10% of consolidated revenues. We also have guarantee obligations of up to $923 million of that amount. Few defenses exist to the liability imposed by OPA. The Clean Air Act, as amended, restricts emissions into the atmosphere. We utilize third parties to dispose of waste water associated with our operations. These reductions may cause the cost of allowances to escalate significantly over time. Mr. Kurtz was appointed Vice President of Marketing and Transportation in May 2011. "Bcf" One billion cubic feet of natural gas. "E&P" Exploration for and production of natural gas, oil and NGLs. "Exploitation" The development of a reservoir to extract its natural gas and/or oil. Also referred to as "proved reserves." To the extent we do not drill the wells, our rights to acreage can be lost. In December 2019, COVID-19 was reported to have surfaced in China. Actual downgrades in our credit ratings may also impact our interest costs and liquidity. ITEM 1B. UNRESOLVED STAFF COMMENTS.None.
