KING ISLAND -- Patches of blue peek through the vast canopy of gray as Rick Stelzriede turns a key in the ignition and points his bow toward open water.
Another day beckons as the only postal worker in California who still delivers mail by boat heads out on the Delta to complete his appointed rounds.
"I'm a wilderness kind of guy," Stelzriede shouts over the roar of the engine as he opens the throttle. "I love being out here every day."
The 61-year-old Tracy resident has been cruising up and down 57 miles of waterways six days a week through rain, fog, thunder, hail and sun since he signed on with the U.S. Postal Service as an independent contractor about two years ago.
Although mail delivery by water existed as far back as the early 1900s, overland routes gradually became the norm as communities grew and roads were built or improved.
Stelzriede's shift starts in Stockton, where he piles the day's mail in his Chrysler SUV and sets out along the approximately 23-mile land portion of the route.
Arriving at King Island Resort by mid-morning, he climbs aboard his 21-foot aluminum runabout to complete the second leg.
With a slightly tattered U.S. flag flapping from the stern, Stelzriede makes his way toward Venice Island, the first of 22 stops that take him through a spiderweb of tributaries and inlets.
He delivers the goods to cattle ranchers and migrant farm workers as well as yacht and hunting clubs, wineries and marinas.
Carrying out his duties is serious business for Stelzriede, who keeps a tide chart on hand so that he can plan deliveries to homes that are inaccessible by boat when the water's at low ebb.
"He'll do anything for his customers," said Alfred Herrero, manager of Stockton's Calaveras Station post office.
Stelzriede's contract only requires him to service mailboxes, but he said he'll get out of his boat to knock on someone's door if they need to sign for a delivery instead of making them drive to the post office.
In the 8½ years that Carl Wenske has managed Bullfrog Landing Marina, he can't recall Stelzriede ever missing a delivery.
"It's definitely a convenience," he said, noting that his only option would be to drive the eight miles from Lower Jones Tract to the post office in Holt.
Deliveries sometimes include prescription medications, packages of pork rolls and CDs from Peru to the sheepherder far from home.
Sometimes what he offloads requires handling with extra care: Stelzriede has dropped off bags of tiny saplings, brought pheasant chicks to gun clubs preparing for hunting season, and brought several pairs of swans to St. Francis Yacht Club, which wanted to use the birds to beautify its private island.
Nearing Venice Island, he grabs a handful of letters, hustles to the back of the boat and leans over the side to stuff a mailbox as he glides by.
Stelzriede chuckles as he recalls the time he had to jump into the water to catch up with his boat when the rope attached to the vessel slipped out of his hand as he disembarked to make a delivery.
Luck smiled on him that day because the direction of the tide worked to his advantage and the boat wasn't in gear, but Stelzriede was chastened.
"I felt like a chump," he said.
Stelzriede keeps a short-handled net at the ready -- it's come in handy on the rare occasion that he's had to fish letters out of the drink because a gust of wind or the current moved the boat away just as he was reaching for a mailbox.
Not only is Mother Nature a wild card, but she can be dangerous: Stelzriede was about his work once when the combination of a strong wind and a large wake from a cruiser created waves so choppy that a couple of them broke over the top of his boat.
"It was like a washing machine," he says.
Stelzriede must stay alert for potential obstacles such as duck blinds obscured by fog so thick that it can shroud the end of his boat, fallen trees that were washed into the river at high tide, inattentive water skiiers and offshore boats that he's had to swerve to avoid when they came speeding around a blind corner.
But offsetting the rigors is the beauty of the Delta.
"See him? See him right there?"
Stelzriede points to a sea lion that has come up for air with a fish between its jaws as seagulls hover overhead, poised to seize any scraps.
Otters, muskrats, mink, beavers and snakes are a part of the scenery; so, too, are herons, osprey and cormorants. Stelzriede has spotted coyotes and raccoons swimming between islands and glimpsed pet pigs nibbling on water hyacinth.
The silhouette of Mount Diablo serves as a reference point as Stelzriede navigates the maze of channels. Although he keeps a map of the Delta behind his steering wheel, he's so familiar with the topography that finding his way around is no more difficult than if he were in his own neighborhood, he says.
"If I got lost, I'd be an idiot."
Considering himself fortunate to have a job that never gets dull and gives him a sense of accomplishment, Stelzriede pours himself into it with the fervor of a man on a mission.
"I think this job's specially made for me," he said.
And it's unlikely that Stelzriede will give it up any time soon.
"I'll probably do this until I die," he said. "I hope. If I'm so lucky."
Contact Rowena Coetsee at 925-779-7141. Follow her at Twitter.com/RowenaCoetsee.
HOMETOWN: San Francisco
FAMILY: The father of five lives with his girlfriend in Tracy
CLAIM TO FAME: California's only mail carrier with a river route
HOW HE LANDED THE JOB: Stelzriede introduced himself to the 72-year-old postal worker who previously had the route and asked whether he could shadow him, thinking it would be fun to spend a couple of hours on the river. The mentorship quickly turned into a part-time job, and about two years ago he took over the route.
OTHER GIGS: Before becoming a mail carrier, Stelzriede worked a variety of jobs from repairing and maintaining swimming pools, building bank vaults, managing a marina, handling deliveries for a construction company, and helping tow and salvage disabled boats.
QUOTE: "I like to think I'm helping all these people. I feel totally accomplished at the end of a day."