NASHVILLE (AP) - Weather conditions that have dried parts of the Tennessee River valley to drought status are expected to persist across a hotter than usual summer.

The lack of rainfall is posing challenges for river management to preserve recreation, water quality and municipal water supplies.

As summer settles in, any significant rainfall will be limited to passing cold fronts. Most of the rain will come from typical convection thunderstorms, which are short-lived and spotty.

The issue isn't only what rain is or isn't coming down, but also the moisture evaporating.

National Weather Service meteorologist Bobby Boyd recently installed an evapotranspiration gauge at his house near Nashville.

"It measures just the reverse of what a rain gauge measures," Boyd said.

Since the first of June, Boyd has been recording about 0.2 inch of moisture evaporating daily from his lawn and its trees. He expects that to increase to abo ut 0.4 inches per day on the hottest days.

"If you get a half-inch of rain today, you'll lose that over the next couple of days," Boyd said. "A half-inch of rain isn't going to go very far."

The drought is at its worst in western Kentucky, while abnormally dry conditions exist in West Tennessee, north Alabama and on portions of Tennessee's Cumberland Plateau, according to the NWS.

The Tennessee Valley Authority is watching the situation and moving water from reservoirs to meet minimum standards of stream flow.

It's a delicate balance, said Susan Jacks, an agency adviser on river scheduling. The river flows from Knoxville to Chattanooga, across north Alabama and then up to the Ohio River. Its watershed includes much of Tennessee and portions of Georgia, Alabama, Mississippi and Kentucky.

"Of the 49 reservoirs, those on the upper East Tennessee tributaries are all in good shape," Jacks said.

Once the river makes the bend and flows through Pic kwick Landing Dam, the tributary sources become less helpful because of dry conditions and a lack of runoff. So far, moving the water downstream has proved effective.

"Kentucky (Lake) is the only reservoir on the Tennessee River that we're not in the normal operating range," Jacks said.

The river management constraints are numerous. Stream flows must be maintained within prescribed limits to provide drinking water, haul away treated waste water, keep barge traffic moving and allow people to boat and fish for recreation.

Marinas are beginning to see marginal effects.

Rita Wessinger and her husband own Sportsmen's Anchor Resort & Marina with 142 boat slips on the western shore of Kentucky Lake at the mouth of Jonathan Creek.

"There's one dock where on one side of it, you have to hug the dock to get your boat into it, but the others are fine," said Wessinger.

Wessinger said many customers have year-round leases. Business has not suffered b ecause of lower water levels, Wessinger said.

The U.S. Army Corps of Engineers controls water flow on the Cumberland River. Barkley Dam at Grand Rivers, Ky., is the last dam before the river reaches the Ohio River.

Corps Ranger David Landis said Friday that Lake Barkley was about 18 inches below its usual summer pool level.

"Recreation hasn't slowed down," Landis said. "There are still boaters out there. There are still fishermen out there."

If the stream flow isn't replenished and the lake level drops as low as typical winter pool, Landis said small mud islands would begin to appear and the lake would pull back from its banks. So far, there have been no navigational issues, either for commercial barges or pleasure craft.

Barkley Dam and nearby Kentucky Dam, on the Tennessee River, continue to use water from the lakes for hydro generation of electricity.

Meteorologist Christine Wielgos at the Paducah NWS office said rainfall is about 11 inc hes below normal in western Kentucky. The Drought Assessment Monitor maintained by the National Oceanographic and Atmospheric Administration - the parent agency of NWS - showed much of western Kentucky is in a severe drought.

Dry conditions in western Kentucky had people literally praying for rain. More than 150 churches in the Ballard, Livingston, Marshall, McCracken and Massac counties were invited to take part from their own pulpits on Sunday. Some rain fell thereafter. The rain gauge at the Paducah NWS office registered 0.39 inches on Monday.

Asked Tuesday if there was enough rain to dent the drought, meteorologist Christine Wielgos replied, "Oh, gosh, no."