Author: David Henry Bennett
Publisher:
ISBN:
Category : Coeur d'Alene Lake (Idaho)
Languages : en
Pages : 160

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Author:
Publisher:
ISBN:
Category : Conservation of natural resources
Languages : en
Pages : 396

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 114

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This study was initiated in the fall of 1981 to delineate the extent of successful shoreline spawning of kokanee salmon in Flathead Lake and determine the impacts of the historic and present operations of Kerr and Hungry Horse dams. An investigation of the quantity and quality of groundwater and other factors affecting kokanee reproductive success in Flathead Lake began in the spring of 1982. A total of 719 redds were counted in 17 shoreline areas of Flathead Lake in1983 compared to 592 in 1981 and 1,029 in 1982. Shoreline spawning contributed three percent to the total kokanee spawning in the Flathead drainage in 1983. Fifty-nine percent of the redds were located above 2883 ft, the operational minimum pool. The majority of those redds were constructed between 2885 and 2889 ft. In areas above minimum pool, intergravel dissolved oxygen concentrations were adequate for embryo survival and exhibited a decrease with depth. Limited data indicated apparent velocity may be the key in determining redd distribution. Seventy-five percent of the redds located below minimum pool were constructed in a zone between 2869 and 2883 ft. In individual areas, apparent velocity measurements and intergravel dissolved oxygen concentrations were related to redd density. The variation in intergravel dissolved oxygen concentrations in the Yellow Bay spawning area was partially explained by lake stage fluctuation. As lake stage declined, groundwater apparent velocity increased which increased intergravel dissolved oxygen concentrations. Mean survival to the eyed stage in the three areas below minimum pool was 43 percent. Prior to exposure by lake drawdown, mean survival to the eyed stage in spawning areas above minimum pool was 87 percent. This indicated habitat most conducive to successful embryo survival was in gravels above 2883 ft. prior to significant exposure. Survival in redds exposed to either extended periods of drawdown or to temperatures less than -10% was significantly reduced to a mean of 20-30 percent. Survival in individual spawning areas exposed by lake drawdown varied from 0 to 65 percent. Groundwater reaction to lake stage explained some of the variation in individual spawning area survival. Three types of groundwater reaction to lake stage were identified. Increased survival in exposed redds resulted from two of the three types. A significant statistical relationship was determined between embryo survival and the number of days exposed by lake drawdown. The operation of Kerr Dam in 1983-84 was characterized by an early decline in lake stage, a longer period near minimum pool and a later and more rapid filling compared to the operation seen in 1981-82 and 1982-83. Based on the survival relationship observed in natural redds exposed by drawdown in 1983-84, complete mortality from exposure would have occurred to all redds constructed above 2884.7 ftor 90 percent of all redds constructed above minimum pool. Emergence traps placed over redds below minimum pool in Gravel, Blue, and Yellow bays captured fry in Gravel and Blue bays only. Duration of fry emergence in1984 was three weeks longer than in 1982 or 1983, but was not related to the date of initial redd construction. Survival to fry emergence in Gravel Bay was calculated to be 28.9 percent of egg deposition or 57,484 fry. Survival to fry emergence above and below the zone of greatest redd density was 33.6 and 245 percent, respectively, indicating a relationship between survival and spawner site selection. After analysis of the historic operation of Kerr Dam, it is believed that the dam has, and is continuing to have, a significant impact on successful shoreline spawning of kokanee salmon in Flathead Lake. Based on the evidence that prolonged exposure of salmonid embryo by dewatering causes significant mortality, the number of days the lake was held below various foot increments (2884 ft to 2888 ft) during the incubation period was investigated. The annual change in the number of days the lake was held below 2885 ft was further investigated because 80-90 percent of the redds constructed in spawning areas above minimum pool during this study were above this level. The operation since 1977 was found to be the least conducive to successful shoreline spawning since the earliest operation of the dam. A significant relationship was established between female kokanee length, which is a measure of year class strength, and the number of days that lake levels were held below 2885 feet from 1966-1983. This relationship indicated that kokanee year class strength in Flathead Lake has been affected by the operations of Kerr Dam. The addition of lake level data improved the correlation in the Flathead River gauge height model, indicating kokanee year class strength has been affected by the operations of both Kerr and Hungry Horse dams.

Author: David Henry Bennett
Publisher:
ISBN:
Category : Fish culture
Languages : en
Pages : 218

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: United States. Bureau of Sport Fisheries and Wildlife
Publisher:
ISBN:
Category : Fish-culture
Languages : en
Pages : 32

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Author: Robert J. Behnke
Publisher:
ISBN:
Category : Nature
Languages : en
Pages : 310

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Author: United States Environmental Protection Agency (EPA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781726089128
Category :
Languages : en
Pages : 190

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Ambient Water Quality Criteria for Cadmium

Author: National Research Council
Publisher: National Academies Press
ISBN: 0309097142
Category : Political Science
Languages : en
Pages : 505

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For more than 100 years, the Coeur d' Alene River Basin has been known as "The Silver Valley" for being one of the most productive silver, lead, and zinc mining areas in the United States. Over time, high levels of metals (including lead, arsenic, cadmium, and zinc) were discovered in the local environment and elevated blood lead levels were found in children in communities near the metal-refining and smelter complex. In 1983, the U.S. Environmental Protection Agency (EPA) listed a 21-square mile mining area in northern Idaho as a Superfund site. EPA extended those boundaries in 1998 to include areas throughout the 1500-square mile area Coeur d'Alene River Basin project area. Under Superfund, EPA has developed a plan to clean up the contaminated area that will cost an estimated $359 million over 3 decades-and this effort is only the first step in the cleanup process. Superfund and Mining Megasites: Lessons from Coeur d'Alene River Basin evaluates the issues and concerns that have been raised regarding EPA's decisions about cleaning up the area. The scientific and technical practices used by EPA to make decisions about human health risks at the Coeur d'Alene River Basin Superfund site are generally sound; however, there are substantial concerns regarding environmental protection decisions, particularly dealing with the effectiveness of long-term plans.

Author: Albert L. Farley
Publisher: University of Washington Press
ISBN: 9780774800921
Category : British Columbia
Languages : en
Pages : 148

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Book Description
The Atlas of British Columbia is the first majorcartographic study of the province to be published since 1956. Createdthrough close co-operation between government, the private sector, andthe unviersity, it is the successor to the British Columbia Atlasof Resources which, for twenty years, has been the standardreference work used by schools, industry, government, and the generalpublic. The most recent data available have been used to give an accurate,comprehensive picture of British Columbia's economy as it is today.Comparative studies show the development orf the province'smanpower and natural resources as well as the rapid growth of industryand technology since the beginning of the century. In party, theemphasis of the atlas reflects thousands of specific requests forup-to-date resource information rercorded over the last ten years.