exhibit 10. 1 amendment no. six to underground coal sales agreement this amendment no. six to underground coal sales agreement ( “ amendment no. six ” ), by and between san juan coal company, a delaware corporation ( referred to herein as “ sjcc ” ) and public service company of new mexico, a new mexico corporation, and tucson electric power company, an arizona corporation ( collectively referred to herein as the “ utilities ” ) ( with sjcc and utilities herein sometimes collectively referred to as “ parties ” ), further amends that certain underground coal sales agreement, dated august 31, 2001, as amended ( the “ ug - csa ” ), between sjcc and the utilities. recitals whereas, the utilities are part owners of the four unit san juan generating station ( “ sjgs ” ) along with the county of los alamos ( “ los alamos ” ), utah associated municipal power systems ( “ uamps ” ), city of anaheim ( “ anaheim ” ), southern california public power authority ( “ scppa ” ), city of farmington ( “ farmington ” ), m - s - r public power agency ( “ msr ” ), and tri - state generation and transmission association, inc. ( “ tri - state ” ), and all nine owners are collectively referred to as “ owners ”, and whereas, sjcc owns and operates the san juan underground mine ( the “ ug mine ” ) that provides coal for the operation of sjgs, and whereas, san juan transportation company ( “ sjtc ” ) may hold certain assets that have been used in conjunction with coal deliveries to sjgs, and whereas, sjcc and sjtc are wholly owned subsidiaries of bhp billiton new mexico coal, inc. ( “ bbnmc ” ), and whereas, on may 12, 2014, the united states environmental protection agency, proposed to approve revisions to the new mexico regional haze state implementation plan ( “ sip ” ) that address the best available retrofit technology requirement for oxides of nitrogen ( nox ) for sjgs, which revised sip, among other things, requires the shutdown of units 2 and 3 of sjgs by the end of calendar year 2017, and x whereas, no later than december 31, 2014, the sjgs owners desire to have as much certainty as reasonably possible about coal pricing for coal sales to sjgs for periods