The far horizon

A lively recreational jewel

A flood of trivia

Great tales surrounding the lake

TODAY

Ecosystem under threat

Lake has impact on weather

Small island is a refuge for birds

Islands in the salt

Lake defines geology of northern Utah

Great Salt Lake timeline

THE FUTURE

Looking ahead

Lake pumps still waiting for flood

Myriad firms thrive off lake

Dike it, dye it, blow a hole in it

Is plan for lake great?

By Jose Luis Sanchez Jr.
Deseret News staff writer

      Source of life, wealth and disaster, the Great Salt Lake is the most important geological feature of northern Utah.

At the height of the mating season in May, some areas of Antelope Island are awash in yellw-headed blackbirds, with their vividly hued feathers. Paul Barker, Deseret News

      Perhaps the most important fact about the lake is that it is the lowest point of a 22,000-square-mile drainage basin. That is what makes it possible for the Bear, Weber and Jordan rivers and other streams to converge here, making an oasis where a desert might otherwise exist.
      A few geological changes and this might be dry little Winnemucca, Nev., instead of the Greater Salt Lake metropolitan area, with enough river water to support 1.2 million people, hundreds of thousands of acres of farmland and many industries. The water also supports millions of birds in one of the most important avian habitats in the world.
      At 4,200 feet above sea level, the lake has a surface area of 1,500 square miles, making it the world's fourth largest lake without a river outlet. At 75 miles long and 30 miles wide, it's the largest lake in the western United States.
      And one of the richest.
      Its lack of an outlet to the sea has permitted the lake to hoard a unique treasure. It contains 4 billion to 5.5 billion tons of dissolved salt and other minerals. That's about 1,300 pounds for every human being in the world.
      The six extraction companies operating on the lake — IMC Kalium Ogden Corp., Magnesium Corporation of America, Cargill Salt, Morton Salt, IMC Salt and North Shore Limited — removed salt and minerals worth $231.6 million in 1997. In 1997-98, brine shrimp and shrimp eggs generated an additional $25 million to $44 million.
      The minerals in the lake are distributed as follows: 55.4 percent chloride, 32 percent sodium, 6.6 percent sulfate, 3.2 percent magnesium and 2.6 percent potassium. The lake also contains smaller amounts of calcium, bromine, lithium, boron and other minerals. Sodium and chloride are the components of salt.
      Without taking into account the annual replenishment of salts from ground and surface water — 3 million to 5 million tons — the Utah Department of Natural Resources estimates it would take 1,000 years to deplete the sodium chloride in the lake to the point extraction became economically unfeasible.
      There are also untapped resources beneath the lake. Deposits of gas, oil and hydrocarbons on the lake are significant but are not being developed because of the high cost of extraction given current technology. The West Rozel field, off the northeastern shore, is estimated to contain 1 million to 10 million barrels of oil.

Ups and downs
      "Variable, transitory, ephemeral." That is how Professor William Lee Stokes of the University of Utah once described the geology of the Great Salt Lake.
      The lake's hydrograph (record of water levels) from the 1850s to the present shows a fluctuation from one year to the next, varying by a total of 20 feet and ranging from a low of 4,191.3 feet in 1963 to a high of 4,211.8 feet in 1986 and 1987. Some experts believe the lake undergoes dry and wet periods, rising steadily for several years and then dropping steadily for several years.
      Because of wetter than normal weather, the lake has been on a rising trend for several years. This year, it peaked at 4,204.6 feet on June 15 and has been dropping since. Whether next year will be another wet one or will mark the beginning of a dry cycle is anyone's guess.
      The lake is very shallow. Its average depth is only 12 feet. At its deepest point — 7.5 miles straight west of the southern tip of Promontory Point — it's only 45 feet deep at high level. Because of the shallowness of the lake and its shores, a relatively small change in lake level can inundate hundreds of thousands of acres of shoreline. At 4,200 feet, the lake covers 1,079,259 acres. Four feet higher, it covers an additional 143,741 acres.
      Given the current state of data collection techniques and computer modeling for weather, snowpack and other conditions affecting the lake and its drainage basin, the Department of Natural Resources can forecast the level of the lake with some degree of accuracy only a few months into the future.
      Beyond that, there is the Nonlinear Time Series Forecasting Model, developed by Upmanu Lall, professor of civil engineering and associate director of the Utah Water Research Laboratory at Utah State University in Logan.
      Combining the lake's current volume and past history with present and historical conditions in the Pacific Ocean, his model can forecast lake levels up to four years into the future, Lall said. However, the model would not be able to predict a sharp change in the lake's pattern such as occurred in 1982-83, he said.
      In 1983, the lake surprised a lot of people when it rose by an unprecedented 5 feet to 4,205 feet and caused $100 million in flood damage. The next year, it went up another 4 feet. In 1986-87, the damage toll jumped to $240 million when the lake rose to 4,211.85 feet.
      Lall believes the 1982-83 flooding was caused by a conjunction of El Nino conditions and something called the North Pacific Deodecadal Oscillation, a cycle of warming and cooling ocean water that peaks every 20 years.
      Lulled by many years of low water, humans had succumbed to the temptation of building at levels they thought the lake would likely never reach again.
      Millions were spent on dikes as motorists on I-80 in Tooele County found themselves "driving on the lake," hundreds of homes in Salt Lake City's Rose Park faced inundation, Davis County sewage plants faced failure and the heavy, salt-laden waves threatened to pulverize a railroad causeway.
      Had the lake continued to rise, it would have caused $500 million to $1 billion in damage, the Department of Natural Resources estimated.
      Future floods could do many millions of dollars in damage.
      The extensive dikes built in response to the floods of the 1980s will prevent some damage in the future. However, Department of Natural Resources estimates indicate future flooding would still have an enormous impact.
      At 4,205 feet, most recreation facilities around the lake such as beaches and marinas would begin to suffer damage. Although the Antelope Island causeway was elevated to 4,208.75 feet in the early 1990s, it also would start to be affected at 4,205 feet.
      This year, as the lake neared its peak of 4,204.6 feet, storm-driven waves eroded the sides of the causeway, forcing the Davis County Department of Public Works to spend over $20,000 dumping rocks and dirt along several miles of the seven-mile road. Now officials must decide whether to go ahead with a plan to again elevate the causeway or wait to see what next year brings. The wrong decision could cost the state and county millions of dollars in tourist revenue if the causeway is again inundated.
      Above 4,208 feet, most wetlands around the lake would be inundated and much of their vegetation would be killed by the salt. During the 1980s flood years, bird populations dropped by 90 percent and state-owned dikes, water-control structures and other property suffered $30 million in damage. Nevertheless, the Department of Natural Resources considers fluctuations in water levels beneficial to wildlife because periodic flooding and drying keeps wetlands young and productive.
      Above 4,211 feet, I-80 would be affected despite the fact that some $20 million was spent in the 1980s to elevate parts of it. At 4,211 feet, IMC Kalium Ogden Corp., one of the lake's major mineral extractors, would have to spend several million dollars on diking.
      Although the Southern Pacific causeway was raised to 4,217 feet in 1987, it began subsiding by 2 to 4 inches a year in the early 1990s. Some areas of the causeway have experienced accelerated settlement of up to half a foot per year.
      At 4,212 feet, damage to several Pacificorp power lines and installations from Salt Lake City International Airport to Kaysville would run to $19.5 million in 1993 dollars. Other power lines near the lake would also be affected.

The great lake quake
      The geology of the Salt Lake Valley floor combined with the proximity of the Great Salt Lake to a major metropolitan area is not a good mix.
      An earthquake of sufficient intensity could cause the valley floor to sink by as much as 5 feet at the fault line along the Wasatch Front. This could create a tilt in the lake bed that would send its waters rushing toward the lowland communities along its eastern shore.
      The massive flooding would be aggravated by a seiche, a wave of water generated by the earthquake. In the worst case, such a seiche could be as high as 10 feet, said Jim Kolva, chief of the Hydrologic Surveillance Section of the U.S. Geological Survey in Salt Lake City.
      A similar seismic event is believed to have created Spring Bay at the lake's northern tip, where the shoreline unexpectedly hooks to the east.
      Short of tilting the lake bed, earthquakes could damage highways, railroads, dikes and other structures along the lake.
      Assuming earthquakes occur randomly, the probability of a large earthquake along the Wasatch Front is 16 percent in the next 50 years and 30 percent in the next 100 years, said Mark Milligan, a geologist with the Utah Geological Survey. If one assumes that quakes follow certain patterns, the probability goes up to over 50 percent in the next 100 years.