<ARTICLE> 5
<LEGEND>
This schedule contains summary financial information extracted from the
unaudited consolidated balance sheet at June 30, 1997 and the unaudited
consolidated statement of income for the six months ended June 30, 1997 and is
qualified in its entirety by reference to such financial statements.
</LEGEND>
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               JUN-30-1997
<CASH>                                           4,160
<SECURITIES>                                         0
<RECEIVABLES>                                   33,163
<ALLOWANCES>                                   (1,085)
<INVENTORY>                                      2,309
<CURRENT-ASSETS>                                42,806
<PP&E>                                         949,756
<DEPRECIATION>                               (259,776)
<TOTAL-ASSETS>                                 738,176
<CURRENT-LIABILITIES>                           41,540
<BONDS>                                        335,980
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           278
<OTHER-SE>                                     281,672
<TOTAL-LIABILITY-AND-EQUITY>                   738,176
<SALES>                                         96,102
<TOTAL-REVENUES>                               106,002
<CGS>                                           21,865
<TOTAL-COSTS>                                   77,940
<OTHER-EXPENSES>                                     0
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                              12,519
<INCOME-PRETAX>                                 28,062
<INCOME-TAX>                                     9,822
<INCOME-CONTINUING>                             18,240
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    18,240
<EPS-PRIMARY>                                      .66
<EPS-DILUTED>                                      .66