NAVAJO DAM, N.M. — A trio of wading fly fishermen worked the Texas Hole in search of rainbows and browns last week as the sound of trickling water mixed with motorized purring.

Front-loading tractors hummed and beeped in the background, digging a large hole on the southern edge of the San Juan River.

Upgrades are under way at the world-renowned San Juan tailwater fishery, improvements to the trout habitat that officials hope will keep the anglers coming — and keep them happy.

Catch-and-release trout fishing on the 4-mile stretch of river downstream of the dam lures anglers from across the globe and pumps an estimated $20 million to $30 million into the local economy each year, according to a 2008 report by the New Mexico Department of Game and Fish.

Out-of-state visitors include Chris Arnold of Durango, who reported last week that his success on the San Juan has been waning.

"Three years ago, it was super good, and it's gotten more difficult over the last three years. When I started out, I was catching 40-50 fish a day sometimes," he said as he walked away from Texas Hole on a crisp, post-rain afternoon. ". I caught less than 20 today — (about) 12-15. And I had to walk from here down a mile to do it."

According to the Department of Game and Fish, which maintains the fishery and surveys anglers, the rate of satisfaction remains high.

But operating such a popular fishing destination comes with its share of scrutiny, and critics make their concerns known.

"There's a group out there that feels the fishing has declined," said Mike Sloane, the department's chief of fisheries. "We're not seeing it in our numbers, but we're hearing it."

In an effort to address known issues and to further enhance fishing opportunities, crews are tackling $300,000 worth of improvements. That includes creating a sediment retention pond at the mouth of the Rex Smith wash to slow the flow of sludge that rushes off a nearby mesa and directly into the river.

Marc Wethington, the NMDGF's fisheries biologist for the San Juan, said sediment has been a recurring problem since 1999. That's when a dirt berm was constructed next to the Texas Hole parking lot to protect the parking and bathroom facilities from flooding. But the unintentional result was that the berm helped funnel the muddy storm water directly into the river.

"That sediment . covers up the bottom; it smothers the aquatic life on the bottom," Wethington said.

Crews will also work within "The Braids," a section of river located approximately a mile below the dam. They will dig holes in the river's sandstone floor to create pools for trout habitat and use dirt to consolidate some of the islands in an effort to create fewer, but deeper, channels.

"It's about manipulating the flow to where it benefits the fishery and trout habitat," Wethington said.

Sloane said the work will also head off problems that may arise if Navajo Dam gets tapped for more water development in the future. The changes under way now would make the fishery more viable in the event of declining flows, he added.

Estimated completion date for the project is Jan. 8.

"I think we're going to have a good end product," Wethington said. "I think the bulk of the anglers are going to be happy."

According to his survey results, most of them already are. Wethington said 98-99 percent of the anglers he questioned last year "were either satisfied, very satisfied or greatly satisfied."

Wethington said catch rates in the "Special Trout Waters" below Navajo Dam have stayed relatively steady since the mid-1980s, usually in the realm of 1.1 fish hooked per hour. Usage also remains high. Although the last decade saw some dips - Wethington said there were lulls after Sept. 11 and again as the recent recession took hold - the fishery supports approximately 200,000 angler hours annually.

Out-of-staters account for the bulk of the fishing.

Bill Gedeon of Aurora, Colo., visited last week with a large group of friends from Colorado. It's an annual tradition that he's been part of for about six years, though some members of the group have been coming far longer.

Gedeon said he'd had limited success in 2011, netting far fewer fish than he had in past years.

"We're catching fish and we're seeing fish — there's a lot of fish — but it just doesn't seem to be as much as it used to be," said Gedeon, who still classifies himself as a bit of a beginner. "I heard stories about how this was supposed to be the absolute best fishing place in the country, but maybe I'm just expecting too much, you know?

"I don't know - maybe some of the construction they're planning will be an improvement."

Duane Vandeventer of the Denver area has been fly fishing on the San Juan for more than a decade. He, too, noted last week that his catch rate had dipped to about one fish per day. But Vandeventer said his trip to New Mexico is as much about companionship as the fish and he wasn't overly troubled by his meager haul.

"One of our friends caught 10 this morning, so part of it is probably the fisherman," he said with a laugh.

Information from: Albuquerque Journal,