<TABLE> <S> <C>
<PAGE>
<ARTICLE> UT
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
COMPANY'S CONSOLIDATED INTERIM FINANCIAL STATEMENTS AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH CONSOLIDATED INTERIM FINANCIAL STATEMENTS.
</LEGEND>
<S> <C>
<PERIOD-TYPE> 9-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-START> JAN-01-2000
<PERIOD-END> SEP-30-2000
<BOOK-VALUE> PER-BOOK
<TOTAL-NET-UTILITY-PLANT> 1,006,973
<OTHER-PROPERTY-AND-INVEST> 0
<TOTAL-CURRENT-ASSETS> 142,619
<TOTAL-DEFERRED-CHARGES> 153,756
<OTHER-ASSETS> 8,341
<TOTAL-ASSETS> 1,311,689
<COMMON> 45,064
<CAPITAL-SURPLUS-PAID-IN> 127,312
<RETAINED-EARNINGS> 243,999
<TOTAL-COMMON-STOCKHOLDERS-EQ> 416,375
0
0
<LONG-TERM-DEBT-NET> 335,383
<SHORT-TERM-NOTES> 0
<LONG-TERM-NOTES-PAYABLE> 0
<COMMERCIAL-PAPER-OBLIGATIONS> 61,766
<LONG-TERM-DEBT-CURRENT-PORT> 25,000
0
<CAPITAL-LEASE-OBLIGATIONS> 0
<LEASES-CURRENT> 0
<OTHER-ITEMS-CAPITAL-AND-LIAB> 473,165
<TOT-CAPITALIZATION-AND-LIAB> 1,311,689
<GROSS-OPERATING-REVENUE> 481,716
<INCOME-TAX-EXPENSE> 25,974
<OTHER-OPERATING-EXPENSES> 384,281
<TOTAL-OPERATING-EXPENSES> 410,255
<OPERATING-INCOME-LOSS> 71,461
<OTHER-INCOME-NET> (425)
<INCOME-BEFORE-INTEREST-EXPEN> 71,036
<TOTAL-INTEREST-EXPENSE> 21,746
<NET-INCOME> 49,290
0
<EARNINGS-AVAILABLE-FOR-COMM> 0
<COMMON-STOCK-DIVIDENDS> 0
<TOTAL-INTEREST-ON-BONDS> 7,688
<CASH-FLOW-OPERATIONS> 44,469
<EPS-BASIC> 2.19
<EPS-DILUTED> 2.19
</TABLE>
