Refiners watch rising Mississippi, operations normal

* 12 pct of refining capacity at risk in flood areas

* Eight refineries watching river levels

HOUSTON, May 6 (Reuters) - U.S. refiners were watching the
flooding Mississippi River on Friday but said operations at
their plants in Louisiana and Tennessee, equal to 12 percent of
national capacity, remained unaffected by high water that has
destroyed homes and crops from Canada to the Gulf of Mexico.

The eight refineries, seven in Louisiana, are protected
from the river's fury by levees and open ground.

Valero Energy Corp's (VLO.N) 180,000-barrels-per-day (bpd)
Memphis, Tennessee plant was at the center of heavy rains that
are now combining with winter snow melt to send flood waters
south through Louisiana.

"There have been no material impacts to production at
Memphis or St Charles due to flooding," said Bill Day,
spokesman for Valero, the largest independent U.S. refiner.

Valero's 185,000-bpd St Charles refinery is west of New
Orleans in Norco, Louisiana, where Royal Dutch Shell's (RDSa.L)
joint venture Motiva Enterprises has a 234,700-bpd refinery.

Shell has said the high water has yet to affect operations
at the Norco refinery and its 235,000-bpd plant in Convent,
Louisiana, further west along the river.

The U.S. Army Corps of Engineers plans to open on Monday
the Bonnet Carre Spillway on the west side of Norco to send
Mississippi River water to Lake Pontchartrain.

Marathon Oil Corp's (MRO.N) 436,000-bpd Clarksville,
Louisiana refinery, west of New Orleans, has had to adjust
supply schedules due to the flooding, but otherwise was
unaffected, a spokesman said.

East of New Orleans, Exxon Mobil Corp's (XOM.N) 192,500-bpd
Chalmette and Murphy Oil Corp's (MUR.N) 120,000-bpd Meraux
refineries were operating normally while monitoring river
levels and possible flooding, the companies said.

At Exxon's 504,500-bpd Baton Rouge refinery, the nation's
second largest, operations continued as normal, the company
said.
(Reporting by Erwin Seba; Editing by Dale Hudson)