[Barbara Keenan]

http://www.latimes.com/travel/outdoors/la-os-map23aug23,0,3634438.story?coll=la-home-outdoors

Hey, who moved the lake?
Mountains and rivers don’t change, but trails do. One mapmaker works to purge hiking maps of errors.
By Michael Moreau
Special to The Times

August 23, 2005

TOM HARRISON stares out at a lake that doesn’t exist ? at least not according to the U.S. Geological Survey map he holds in his hand.

“I’m just trying to compare what’s on the map with what’s on the ground,” says the onetime California state park ranger whose niggling habit of correcting maps turned into a business.

The government-issued maps that backcountry users have relied upon for years simply don’t get updated. In many cases, they are based on data collected 50 years ago. And while the federal agencies realize that the maps contain errors, they say it’s not their mission to correct them. That’s where Harrison and other mapmakers come in.

On this clear July morning, Harrison walks about an hour up an unnamed fire road in Marin County’s Rush Creek Open Space Preserve to match the topographic map ? a big green quadrangle on which mountains are reduced to tight contour lines and rivers become thin blue squiggles ? with the terrain.

To do so, the wiry 58-year-old with the taut body and bronzed skin of a man who has spent years outdoors spins a measuring wheel in the dead center of the path to record the mileage. As egrets swoop through trees to land in a nearby marsh, he walks clear of the trail’s oak canopy to take a reading from satellites that bounce data back to his GPS device. This mile-plus hike will be an easy day’s work for Harrison, who treks as much as 15 miles into the Sierra to gather accurate data.

The trail is even and nicely shaded from the advancing sun. In less than an hour he has reached the peak and discovered the lake. A levee that adjoins the Petaluma River has evidently broken, and the escaping water has formed a fair-size pond that’s alive with waterfowl. He makes comments into his tape recorder; this new body of water will appear on his map due out next spring.

“Maps are really only three things: lines, color and type,” Harrison says. But the challenge is to get all three elements just right so hikers can find their way in places where little details make a big difference.

“Harrison’s are the Cadillac of maps,” says Tom Reponen, assistant recreation officer of the L.A. River District of the Angeles National Forest, who helped proofread the mapmaker’s newest map of the local forest.

Between the lines

TOPOGRAPHIC maps have been used by hikers and backpackers since before John Muir first caught a glimpse of Hetch Hetchy Valley. Nicknamed topos, they date to the 1880s and divide the country into 54,000 neat quadrangles with lines and squiggles that represent the contour of the land. On most, one-quarter inch equals one mile (except for Alaska, where one inch equals a mile.)

Early topo maps were made from ground observations, but that eventually gave way to using aerial photographs. Tiny numbers denote elevations, indicating the difference in steepness between one contour line and another. Thin lines indicate roads, rivers and trails, and little black squares designate buildings such as ranger stations or visitor kiosks.

To the relief of mountaineers and backcountry trekkers, topography really doesn’t change that much. But what does change with nagging regularity are trail heads, the course of streams and the locations of fire roads, forests and buildings.

For example, the USGS Condor Peak quadrangle of part of the Angeles National Forest above La Ca?ada Flintridge contains at least one error. Harrison points to the words in the upper left section near a point called Indian Ben Saddle that read “Target Shooting Area.”

“That’s wrong,” Harrison says. “There’s no longer any target shooting in any national forest. It probably drives the Forest Service crazy. People look at it and say, ‘Hey! We can go plinking up there.’ “

Fred Dong, who lives in Glendale and leads Sierra Club hikers and backpackers on treks throughout California, says that a trail in Yosemite on the USGS’s Vogelsang Peak quadrangle is “notoriously” wrong.

“The topo shows the trail crossing Rafferty Creek two times, but it actually doesn’t cross the creek at all,” Dong says, noting that he had been warning hikers about getting wet until he realized the error.

Chip Rawlins, co-author of the fourth edition of “The Complete Walker,” has covered roughly every quadrangle in his home state of Wyoming. He says users should beware. If the USGS map says “datum of 1927” and it hasn’t been updated, “you have to assume trails and roads and structures have changed considerably.”

The USGS and its partner in mapmaking, the U.S. Forest Service, say the agencies don’t have the personnel or money to update maps and do the kind of careful checking that Harrison does.

“We provide the topos,” says Leslie C. Gordon, a geologist and communications officer of the Western Region office of USGS in Menlo Park, Calif. “What others do to them is fine with us. Topology has always been our mission. Ours is the baseline, and we are not updating those baseline maps.” The maps, she says, are accurate enough to be used in agricultural or population studies. However, the agency welcomes anyone who tweaks the topos with what the agency calls “value-added usage.”

Harrison fills that niche. After quitting his job with state parks in the mid-1980s, he went back to school to earn a master’s degree in geography. Though mapmaking wasn’t his best subject, it was when he was on a consulting job and visited the premier mapmaker in Vienna, Austria, that a light bulb came on. “I figured I could do this,” he says. In 1987 he and his wife, Barbara, started Tom Harrison Maps.

Checking it twice

HARRISON first mapped the place he knew best: Angel Island in San Francisco Bay, where he had been a ranger. He used USGS maps ? charted from aerial observations made in 1957, 1983 and as late as 1993 ? as the basis and went into the field to check the terrain.

“Ground checking, editing, verification is everything,” says Rich Spradling, chief cartographer for the Pacific Southwest Region of the U.S. Forest Service. “Tom does go out on the ground and does the checking. I joke with him that he gets to do the fun stuff. We’d like to do that.” But the Forest Service, which does fieldwork when it can to update maps, limits checking on foot to the most popular areas.

After Angel Island, Harrison went on to make 43 more maps of California wildlands, collecting data in the wild and putting them together in his home office, which is tucked neatly into the corner of a tastefully decorated townhouse in San Rafael, Calif.

On the desks are two Macs: one for Harrison’s map work, the other for Barbara’s orders and billing for the 75,000 maps the couple send out each year at a price of roughly $8.95 each. In the garage are files containing copies of his maps: Bishop Pass, Mt. Baldy-Cucamonga, Yosemite Valley, Mt. Whitney High Country, Death Valley and Angeles National Forest, divided into two separate maps of the front country and the high country.

Harrison doesn’t just update maps, he creates a kind of customized topo that includes elevations of trail junctions and mileage of trail segments.

Instead of paper, he prints on high-grade waterproof plastic that folds easily but is virtually impossible to crumple or tear. He uses shaded relief on his maps to better highlight gradations of topography and uses different colors for foot and bicycle trails. And Harrison adds extras, such as places where drinking water is available.

“Tom is the best,” says Terry Tanner, a retired civil engineer who is on his own quest to correct maps. “He makes mistakes, but his are the best ones out there.” Harrison’s mistakes, in Tanner’s eyes, are made because he doesn’t compute every linear foot of terrain with a GPS ? a daunting task unless, like Tanner, you own a unit that costs several thousand dollars and carry your own antenna to pick up signals in valleys and forests. Tanner corrected some of the government maps for the Charlton Flat area in the Angeles National Forest, but it’s a slow, painstaking process. “If I just covered the area around Mt. Wilson, it would take me five years,” he says.

Looking ahead

AT the Marin County preserve, Harrison’s revisions take shape. Just past 10 in the morning, he’s already creating the map in his mind. “I’ll have this road on the map and that little stub going off it,” he says, pointing toward a flattening open space. He’s updating the Rush Creek map for the county’s search and rescue team, which will receive a digital file and print out a map whenever one’s needed. A few years from now, Harrison plans to produce a map of Marin County ? stretching from the Golden Gate up to the edges of the Napa wine country ? that shows all trails and public lands.

He makes a note into his voice recorder that the measuring wheel reads 5,405 feet; the unnamed fire road was a little more than mile. He puts away the recorder and collapses the measuring wheel, tucking it into his backpack. With the trail work done for the day, he gets back to his jeep and unloads his pack. Harrison knows he won’t put a dent into the 54,000 USGS maps out there, but he’s content to cater to a California market that appreciates his work.

And even with thorough on-the-ground checking, he knows that changes are inevitable. “I figure my maps are obsolete as soon as I print them,” he says.

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