<ARTICLE> OPUR1
<CIK> 0000318819
<NAME> R. D. SIEVERS
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-END>                               MAR-31-1998
<BOOK-VALUE>                                  PER-BOOK
<TOTAL-NET-UTILITY-PLANT>                    3,740,883
<OTHER-PROPERTY-AND-INVEST>                    113,501
<TOTAL-CURRENT-ASSETS>                         199,461
<TOTAL-DEFERRED-CHARGES>                       276,486
<OTHER-ASSETS>                                  47,675
<TOTAL-ASSETS>                               4,378,006
<COMMON>                                        99,962
<CAPITAL-SURPLUS-PAID-IN>                      332,402
<RETAINED-EARNINGS>                            721,489
<TOTAL-COMMON-STOCKHOLDERS-EQ>               1,153,853
<PREFERRED-MANDATORY>                           79,328
<PREFERRED>                                     17,929
<LONG-TERM-DEBT-NET>                         1,877,244
<SHORT-TERM-NOTES>                             160,192
<LONG-TERM-NOTES-PAYABLE>                            0
<COMMERCIAL-PAPER-OBLIGATIONS>                       0
<LONG-TERM-DEBT-CURRENT-PORT>                   31,303
<PREFERRED-STOCK-CURRENT>                            0
<CAPITAL-LEASE-OBLIGATIONS>                          0
<LEASES-CURRENT>                                     0
<OTHER-ITEMS-CAPITAL-AND-LIAB>               1,058,157
<TOT-CAPITALIZATION-AND-LIAB>                4,378,006
<GROSS-OPERATING-REVENUE>                      226,000
<INCOME-TAX-EXPENSE>                            13,874
<OTHER-OPERATING-EXPENSES>                     154,084
<TOTAL-OPERATING-EXPENSES>                     167,958
<OPERATING-INCOME-LOSS>                         58,042
<OTHER-INCOME-NET>                                  92
<INCOME-BEFORE-INTEREST-EXPEN>                  58,134
<TOTAL-INTEREST-EXPENSE>                        36,546
<NET-INCOME>                                    21,588
<PREFERRED-STOCK-DIVIDENDS>                        996
<EARNINGS-AVAILABLE-FOR-COMM>                   20,592
<COMMON-STOCK-DIVIDENDS>                        16,346
<TOTAL-INTEREST-ON-BONDS>                       34,834
<CASH-FLOW-OPERATIONS>                          59,033
<EPS-PRIMARY>                                     0.26
<EPS-DILUTED>                                     0.26