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Rock Lake--divers say it’s the best-kept secret in New Mexico. Technical divers test mixed gases and equipment in its 290-foot (88 m.) depths. National Park Service divers train for cold water exploration in its 60-degree F. (15C) or less currents. Select sport divers call it their own private dive site. Me, I call it fun as I swim with terrapins amid its unique aquatic life, freshwater sponges and algae curtains.
Divers from New Mexico, Colorado and West Texas know of the Blue Hole near Santa Rosa, easily the state’s most well-recognized recreational and training dive site.
But, only a few miles from Blue Hole, tucked in a grassy valley inside the boundaries of Agua Negra Ranch, sits lesser-known Rock Lake, a deep artesian spring, and its smaller neighbor, Swan Lake. Unlike Blue Hole which is open to the public, access to Rock Lake and Swan Lake is by reservation only and is limited to experienced, advanced divers working through a dive shop. “We work with shops in Colorado, West Texas, even Nebraska, in addition to New Mexico,” says Deborah Ladyhawk, owner of Agua Negra, a working cattle and horse ranch.
“The colors of the water are amazing! It’s hard to describe!” raves diver Matthias Geissel of Albuquerque, New Mexico and Frankfurt, Germany.
“When you’re below, around 80 to 100 feet or so, you look down and see nothing, like a black abyss. Then you look up toward the sun and it’s this incredible green--sort of emerald but not quite. It’s indescribable. I’ve never seen anything like it in the world.”
Will Ferrell of Albuquerque, a long-time diver of Rock Lake, finds the huge, angled limestone slab walls fascinating. “Look up and down the wall for a hundred feet. These rock formations are amazing.”
Ferrell and his dive buddy John Wills of Los Alamos enjoy exploring a rock formation called “The Crack” or “The Flake.” Gesturing with his hands, Ferrell explains, “It’s called the ‘Flake’ because a large house-sized boulder has ‘flaked’ off the wall leaving a V shape between the boulder and the wall. Daring divers can swim in the V created by the parting.”
Me, I’ll never forget the first time I descended and nearly landed on a yellow-eared terrapin the size of a Thanksgiving turkey platter. A little deeper I noticed wads of what looked like toilet tissue stuck in between rocks. Disgusting, I thought. After the dive, Will asked, “Did you see the freshwater sponges?”
“No, I replied.
“How could you miss them? They look like wads of toilet tissue!”
“If we’re involved with sites that are cold and deep, we train and test equipment at Rock Lake first,” verified Daniel Lenihan of the National Park Service (NPS) Submerged Resources Center in Santa Fe.
Lenihan is a NPS archeologist, technical diver and author of the book Submerged.
Before exploring a Confederate wreck in the English Channel in 1993, Lenihan and his dive staff trained and tested equipment and cameras at Rock Lake. “The CSS Alabama lies in 200 feet of cold water near Cherbourg, France, in conditions similar to Rock Lake.”
In 1994, the NPS partnered with KOBTV and the Museum of Natural History to broadcast live and interactive from Rock Lake to the Museum in Albuquerque. “Students could ask questions and I answered them from underwater,” Lenihan recalls.
“It’s a great way to give kids from a landlocked state a connection to the precious water resources in their own back yards.”
In other projects, the NPS tested remoteoperated vehicles (ROVs) and did a series of work-up dives with mixed gases. “This was in preparation for a dive in Lake Mead. A B-29 [World War II-era bomber] lies about 200 feet deep, in lighting, depth and water temperature similar to Rock Lake.”
He continued, “Rock Lake is perfect for the Park Service to test new instruments for mapping, water sampling, and sonar, all kinds of instruments or repairs. It’s nearby and diveable year-round.”
Rock Lake’s water temperatures vary seasonally but not drastically. By contrast, Blue Hole, which is entirely spring fed, stays at a constant temperature year-round.
But Rock Lake has both surface water and spring water. This results in seasonal variations of ten degrees F (6 C). in shallower depths and little variation at greater depths. Divers generally report temperatures in the 60s F (mid-teens C).
“Divers have told me that coming off the wall, they found a natural pipeline of warm water, a sort of geothermal vent,” offers Ms. Ladyhawk. “I have to take their word for it, because I don’t dive,” she adds with a smile.
According to a survey done in 2002 by Tom Taylor and Vince Vekan of the National Speleological Society Cave Diving Section, the lake measures 290 feet (88 m.) deep at the north end and 230 feet (70 m.) at the south end.
In addition, Taylor and Vekan discovered that the lake extends 100 feet (33 m.) further north underground.
However, they weren’t able to map the entire floor of the lake and little is known of the lake’s deep bottom. “We assume it’s mud and silt because we see silt on the walls,” said Ferrell. On a dive to the shallow bottom of Rock Lake, Ferrell added, “At 206 feet, I stuck my hand in silt.”
Divers also notice a slight current, probably due to the as yet unmapped underground spring that recharges Rock Lake with 6,000 gallons per minute. This underground spring also nourishes nearby fish hatchery via a pipeline at the north end of the lake.
If he’s not tech diving, Kevin Eddy of Albuquerque enjoys sport diving at Rock Lake when he and his friends reserve it for a weekend. Sitting under his canopy between dives, he sips bottled water and gazes across the lake.
He reflects on the dive he and his buddy just completed. “We went down near the pipeline to about 35 feet (10 m.) and hit the thermocline. Then we turned and swam east, descending to 85 feet (28 m.) or so. All along the east wall were those incredible rock formations. You need a powerful light to appreciate them,” he added as an afterthought.
“Near the south end, we saw these weird green curtain-like hangings—moss, algae, I don’t know, but they’re fascinating. Then we looked for turtles in the grass, but we were too deep.”
He watches a huge crane glide into a Russian olive tree on the shore, scattering a small flock of swallows. Overhead, altocumulous clouds float in a clear blue sky. No sounds disturb the stillness until a largemouth bass grabs at a blue damselfly, splashing the surface into ripples. A yellow-eared terrapin about six inches wide pokes its head above water, breathes for a few seconds then scoots back under the water.
“I’ve dived here at least 10 times before, but it’s different every time. You always see something you didn’t see before. Rock Lake is really special. It’s your own private dive site for the day—no crowds, just you and your friends.”
Divers wishing to dive Rock Lake must make arrangements through a dive shop. Dive shops may contact Agua Negra Ranch at 505- 472-4103 or firstname.lastname@example.org. In addition to signing a release, providing a copy of their advanced certification card and paying an entry fee, divers must bring their own equipment, air, food and water. Tanks and air fills (no Nitrox) are available at Santa Rosa Dive Center at the Blue Hole about 15 minutes away.
Rock Lake is diveable year-round. In warm months, 7 mm wetsuit with hood or drysuit is comfortable. In colder months, a drysuit is preferred.
Admission to Rock Lake also includes nearby Swan Lake, a quarter of a mile north of Rock.
Swan Lake is shallower, warmer and was used for instruction in the early 90s. At Rock Lake, divers utilize a concrete dock and metal ladder for entries and exits. At Swan Lake, however, there is no dock and divers must negotiate slippery rocks for shore entries and exits.
All diving is done at the diver’s own risk. Agua Negra does not provide site supervision or telephone service. Divers are strongly urged to bring cell phones and first aid supplies. The nearest recompression chamber is in Albuquerque, approx. 2 hours by freeway.
Agua Negra is a working ranch. Respect the land and lock all gates.
c. Dive Chronicles 2006