Wholesale electricity rates in the Tennessee Valley will rise 12 percent on April 1 due to the combined impact of a base rate increase and higher fuel costs, TVA announced today.

Tennessee Valley Authority spokesman John Moulton said the fuel cost adjustment for the spring quarter announced late today will push up TVA rates by nearly 5 percent from the current level. Last week, TVA directors approved a 7 percent increase in the agency’s base charges for electricity.

For the typical household, the combined increases will raise monthly electric bills from $6 to $12, depending upon the season and usage, Mr. Moulton said.

“Persistent drought conditions across Tennessee and the resulting lack of hydro generation continue to negatively impact TVA,” he said.

Last week, TVA President Tom Kilgore said TVA was raising its base rates for the first time in about 18 months.

The combined 12 percent jump in rates in April will be the biggest one-time increase in TVA electric charges in more than two decades.