Web Resources Utah Geological Survey U.S. Geological Survey Utah Division of Wildlife Resources: Great Salt Lake Great Salt Lake Basin hydrologic observatory proposal FRIENDS of the Great Salt Lake Greater Salt lake ecoregion virtual tour and learning module. Courtesy R. Ford, Professor, Loma Linda University Web links to other saline lakes. Courtesy of R. Ford, Professor,Loma Linda University Lake Effec t of the Great Salt Lake: Scientific Overview and Forecast Diagnostics DWR Great Salt Lake Comprehensive Management Plan Resource Document DWR Great Salt Lake Comprehensive Management Plan Decision Document DWR current brine shrimp harvest information First detailed weather observations on the Great Salt Lake Captain Howard Stansbury was instructed by the Army to conduct a mile-by-mile survey of the Great Salt Lake and adjacent regions during 1849-50 Other participants: second-in-command John Gunnison crew forman Albert Carrington Examples of weather observations on the Great Salt Lake: May 1. Sunrise 57F, cirrus. Noon 71F cirrus. 3 PM 69F cloudy. Sunset 63F calm April 16. About 4 oclock a violent gale came up accompanied by thunder and lightning from the west which instantly prostrated most of our tents and a copious fall of hail mingled with rain which wetted the party to the skin. May 8. Gunnison Island. We set out at 5 oclock on our return. When within 3 or 4 miles of camp a most furious gale of wind broke down upon us from the NW, which soon raised such a sea as to render the progress of our heavy boat so slow that we did not reach camp until 10 clock, cold tired & hungry. Reference: Exploring the Great Salt Lake: the Stansbury Expedition of 1849-50. Edited by Brigham D. Madsen. University of Utah Press. 1989. 889 pp. Other notable surveys: Grove Karl Gilbert. 1887-80. U. S. Geological Survey. Chemistry of the Great Salt Lake Much of the salt in the Great Salt Lake was originally suspended in Lake Bonneville while some dissolved salts flow into the lake each year Prior to the completion of the causeway in 1959, the Great Salt Lake was a relatively homogeneous saline lake Now, even with larger openings in causeway created in 1984, Gunnison Bay (north arm) is quite different from Gilbert Bay (south arm). See the accompanying table. U.S.G.S. samples lake monthly When differences in height of Bays are large, head drives surface flow of lighter water near surface into North Arm through gaps When differences in salinity of Bays are large, deep flow of saltier water flows from North Arm into South Arm through permeable causeway During winter (prior to record lake levels), mirabilite (sodium-sulfate compound) precipitates out in the North Arm. As water warms, layer of mirabilite goes back into solution and forms sulfur-rich layer near bottom that persists and may flow into South Arm During summer, sodium chloride precipitates on floor and will remain on floor until salinity decreases significantly Strong wind storms may cause hydrogen-sulfide rich bottom layers to be mixed to surface and contribute to "Lake Stink" as well as expose decomposing sulfur-rich mud flats Thermodynamics of the Great Salt Lake  <>Annually averaged vertical profile of temperature indicates that North Arm is warmer near the surface and cooler at depth than the South Arm (source: unpublished summaries provided by W. Gwynn, Utah Geological Survey) <>Annual cycle in temperature of the South Arm (source: unpublished summaries provided by W. Gwynn, Utah Geological Survey) indicates: <>Surface temperature varies from 33.9 F in January to 79.3F in July <>Top 20 feet fairly well mixed during year <>Thermocline (warm water above cold depths) evident at 25-30 feet from April-August while higher temperatures at depth from October-February <>Warmer water at depth is possible, since salinity increases slightly with depth (density more sensitive to salinity than temperature) <> Implications for the atmosphere of thermodynamic structure: <>Strong winds and upwelling bring colder water to surface from April-August <>Strong winds and upwelling bring warmer water to surface from October-February <>lake-effect snowstorms may be more persistent during Fall-early Winter than late Winter-Spring since strong winds in post-frontal environment do not cool off lake significantly Biology of the Great Salt Lake Two primary habitats: Surface layer Algae blooms during winter Brine shrimp hatch from hard-walled eggs (cysts) in April and graze phytoplankton Shrimp grow and reproduce during summer molting in as many as 12 different stages When shrimp stressed by lack of food or environmental conditions, they switch from producing live young to cysts Cysts harvested commercially during Fall and persist in a semi-dehydrated state until the salinity decreases in spring No live brine shrimp survive temperature below 5C (42F) Bottom layer During spring, shrimp consume enough phytoplankton for light to penetrate to depths Photosynthesis by algae in bottom layer provides source of food as well as detritus falling from surface water Two species of brine fly spend larval period on bottom of lake Flies emerge as adults in early summer 110 billion flies plus 10 billion pupae are estimated to hover over 300 miles of beaches (370 million flies per mile of beach) Flies consume algae and waste equivalent to a 78,000,000 gallon per day waste treatment plant Brine shrimp harvests Value of unprocessed brine shrimp eggs in 2004 was $11.8 million In the 1997 General Session, the Legislature passed HB 359, which: (1) levied a brine shrimp royalty tax of 3.5 percent of the value of unprocessed brine shrimp eggs... Brine shrimp royalties have increased in recent months, increasing royalty payments to the restricted Species Protection fund. This allows for an increased appropriation to replace General Funds lost during recent budget cuts and to fund more projects. General Fund Restricted Species Protection.........$412,800