Friday, Dec. 29, 2006 | 7:21 a.m.
National Park Service Ranger Brandon Marsmaker guides his flat-bottomed boat carefully across the upper reaches of Lake Mead, navigating through an aquatic battlefield.
It is here where the cold, muddy Colorado River finally encounters Lake Mead's green, glassy tranquility. Shoals and reefs of wood and debris, as well as sand bars and mud flats, can easily trap boats in this treacherous confluence.
Marsmaker has his eyes on the water, not on the sheer rock walls surrounding Greggs Basin.
A decade ago, when Marsmaker was beginning his career as a ranger, this confluence occurred 10 miles upstream, close to the entrance of the Grand Canyon National Park.
It is one sign - along with the band of yellow and white mineral deposits starkly contrasting on the black and red rock surfaces surround the lake - that conditions in Lake Mead are changing. Demand and drought are causing the lake level to drop.
Lake Mead is a critical water supply for Las Vegas, Southern California and Arizona. Demand for water from the entire Colorado River is also growing upstream from Lake Mead - in Colorado, Wyoming, Utah and New Mexico. Residents of all seven states on the river - especially the 2 million people of Southern Nevada - have a vital interest in the future of the lake.
Everyone is chasing its water.
At the same time, nature is providing less of it. Were it not for a single very good year of rain and snow in the Rocky Mountains in 2005, Lake Mead's upstream cousin, Lake Powell, would be heading for "dead pool" next year, meaning it would not have enough water to send to Lake Mead. If that were to occur, Lake Mead's water levels would plummet quickly.
Those forces of man and nature have quietly established a new reality at Lake Mead - for the communities around it, for recreation enthusiasts and for wildlife.
Pollution from Las Vegas wastewater and urban runoff has become more concentrated than a decade ago, and will only become worse unless something is done.
That's why Lake Mead is the subject of more scientific scrutiny today than at any time in its history. It's also why big plans are under way that will permanently change its relationship with Las Vegas.
A century ago the Colorado River could go from viscous to vicious in a thunderstorm. The river would deliver a relative trickle of water in late fall, then erupt into raging, homicidal rapids with the spring snowmelt high in the Rockies.
Attempts to control the river had been sporadic and only partially successful in the 1800s. By 1905 canals were bringing desperately needed irrigation water from the river to farms in California's Imperial Valley. But it came with a terrible price.
Massive flooding in 1905, 1906 and 1916 scoured thousands of acres of agricultural land in California and Arizona and created a huge inland lake, the Salton Sea. The response to the continuing threat from a savagely unpredictable river was a massive engineering project, completed in 1935 for about $775 million in today's dollars: Hoover Dam, a work counted as one of the most awesome man-made structures on the planet.
The dam did more than tame the wild river, generate cheap hydroelectric power and provide controlled irrigation for millions of acres of former desert. It profoundly transformed more than 100 miles of riverbed carved into desert rock into a reservoir of almost 30 million acre-feet of water - about 10 trillion gallons.
Engineers knew that they could do more with the massive lake than simply control flooding and supply irrigation water. They could generate power with the dam's hydroelectric generators, and supply communities with water.
The states in the lower Colorado River basin - California, Arizona and Nevada - and the upper basin - Wyoming, Utah, New Mexico and Colorado - divided up the river's water in 1922 with the Colorado River Compact. They estimated that 16.5 million acre-feet of water flowed down the river annually.
For decades the accuracy of that estimate didn't matter because only California was claiming all of its water allotment. But in time, growing cities - among them Las Vegas - began claiming their allocations. Arizona built a huge network of canals linking the river to its burgeoning urban centers.
By now - in the 1970s - millions of people were fleeing the Northeast and Midwest for the Sunbelt.
They demanded water to support their lifestyle.
And the river had been deceitful in its promise.
The base year on which engineers and public policymakers estimated the amount of available water from the Colorado River turned out to be a wet year, an anomaly, not one on which to build a future of growth.
The river could not be expected to deliver 16.5 million acre feet of water a year, but 20 percent less than that.
Lake Mead was providing the necessary buffer for that river shortfall, but it wouldn't last forever.
Cities and states that had planned on water from the lake and river - a supply that once seemed virtually inexhaustible - now have to plan for shortages.
Five of the last six years have brought drought to the Rocky Mountains and the Colorado River. In 2002 the region received a quarter of its "normal" precipitation.
Worse yet, the patterns of precipitation appear to be changing: More of it is coming as rain, only to evaporate, and less as slowly melting snow. So the river is filling less while demand is paradoxically growing.
The result: Water levels in Lake Mead and - on the other side of the Grand Canyon - Lake Powell are tumbling. The problem threatens water supplies for nearly 2 million people - and millions more visitors - in Las Vegas. It threatens power production, irrigation and drinking water supplies to 25 million people along the Colorado River. The falling water levels complicate efforts to preserve endangered species, and is concentrating contaminants in the lake.
Evidence of the falling lake levels can be found near the once-navigable Iceberg Canyon, at the confluence of the Colorado River and Lake Mead. It is a tumultuous merging, marked by huge, roiling silt clouds, yellow and red.
There was a time, Brandon Marsmaker says, when he used to go into the canyon - and 50 miles up on the river into Grand Canyon National Park. Falling lake levels have made that impossible.
The National Park Service, which manages the lake and the surrounding areas of desert in Nevada and Arizona, has been spending $5 million a year dealing with this new reality. Its staff is building new boat ramps, extending existing ones and moving entire marinas - water treatment plants, gas pumps, electrical power lines and all - because of the falling water levels.
Three boat launches have been closed because of dropping water levels: Pearce Ferry, at the northern end of the lake on the Arizona side; Las Vegas Bay, which once had one of the lake's nine marinas; and Government Wash, east of Henderson.
The Park Service announced this week that the Overton Marina also would move in 2007. Most of the rental boat slips are expected to move to Callville Bay.
At Callville Bay, home to dozens of two- and three-story houseboats, Dale Melville, a Park Service engineer, watches divers and heavy-equipment operators carefully position new, permanent concrete slabs at the Callville ramp.
Two years ago, workers were doing similar work.
"Now we're back down fighting it again," Melville says. "It's going down, down, down."
Indeed, chasing the declining water is a full-time job for the Park Service. Every week that the water falls another foot - and it has fallen about 100 feet in the last six years - new rock reefs emerge, wreaking havoc with even the most experienced boaters.
Park rangers erect signs and light poles on the new hazards - sometimes perched comically, dozens of feet above the water's surface - to warn boaters.
"There is no way our aides to navigation crew can mark every hazard on the lake," Roxanne Dey, a Park Service spokeswoman, says. "Boaters need to be responsible."
The Park Service has gotten good at chasing the water, and today the lake remains a friendly place for houseboaters, water skiers, striped bass fishermen and swimmers - all the recreational uses that have made Lake Mead famous.
"Everything you can do at 1,180," she says, referring to the elevation of the lake surface, "you can do at 1,125.
And sometimes, you can do more.
With water levels falling, the entire town of St. Thomas, which was submerged when Lake Mead filled up six decades ago, is now a walk-up attraction.
Falling lake levels have repercussions far beyond boating hazards.
Its exposed, water-stained walls send a visceral message that there's trouble for the 20 million people who tap it for drinking water and the farmers who use it to irrigate millions of acres of desert.
The seven states and federal Bureau of Reclamation, each of which has a stake in the 1922 Colorado River Compact that led to the construction of Hoover Dam and division of the river's water resources, are trying to figure out how to divvy up the diminishing water.
In February the federal government is expected to release the draft environmental impact statement outlining the new rules.
The rules are likely to include cuts in the amounts that states can use as the drought worsens. But the states and federal government also are looking at ambitious efforts to actually increase the amount of water in the Colorado River and Lake Mead - including cloud seeding to promote snowfall in the Rocky Mountains and eliminating weeds along the river such as salt cedar, also known as tamarisk, a water-hungry Eurasian invader that some scientists estimate sucks up as much water as Las Vegas uses in a year.
Ample snowfall in the Rocky Mountains would be very, very welcome.
Gail Kaiser has spent almost all of her 50-some years at Lake Mead. In 1957, when she was a young girl, her parents, Bob and Betty Gripentog, bought Las Vegas Boat Harbor.
"It was different than most people's childhood," Kaiser says. "When other people were watching Saturday morning cartoons, we were on the lake. We were climbing mountains."
And today they work a lot - leasing 650 boat slips and renting a score of ski and fishing boats.
And they, too, have had to move their marina - and fuel pumps and a restaurant - as the lake level dropped. They are now situated several miles south, at Hemenway Harbor.
"We had to move the entire marina, and we're going to have to push it out again," Kaiser says. That's not a day's worth of work. That's a month's worth of work."
Because they, too, have to keep chasing the water.