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| Title | Water Quality Assessments of Selected Lakes within Washington State - 1994 | |||
| Month-Year Published | February 1997 | |||
| Online Availability |
13164 kilobytes, requires version 4.0 or later of Adobe Acrobat Reader Software get Acrobat Reader
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| Short Description |
The objectives of Ecology′s Lake Water Quality Assessment Program are to identify lakes that are exhibiting water quality problems, to assess significant publicly-owned lakes by estimating the trophic status of monitored lakes, and to promote public awareness of lake ecology and protection. (Also see abstract below) | |||
| Publication Number | 97-307 | |||
| Author(s) | Smith, K. | |||
| Print Availability |
Cost for Washington state residents is $15.00. Cost for non-residents is $15.00.
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| Number of pages | 451 pp. | |||
| Keywords | assessment, bacteria, chlorophyll, fecal coliform, lake, monitoring, nitrogen, phosphorus, secchi disk, temperature, total suspended solids, trend, trophic state index, trophic status, water, Water Quality, watershed | |||
| Subject Waterbodies |
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| Abstract | Long Description |
The objectives of Ecology′s Lake Water Quality Assessment Program are to identify lakes that are exhibiting water quality problems, to assess significant publicly-owned lakes by estimating the trophic status of monitored lakes, and to promote public awareness of lake ecology and protection. In 1994, volunteers participating in Washington′s Citizen Lake Monitoring Program measured Secchi disk transparency and surface water temperature in 55 lakes; volunteers monitored their lakes bimonthly from May through October. Most volunteers also completed a questionnaire on lake and watershed uses. To supplement volunteer-collected data, Ecology staff collected water samples and profile data from all volunteer-monitored lakes, as well as 18 lakes that were not monitored by volunteers. Water samples were collected in May and August from both the epilimnion and hypolimnion of stratified lakes, and were analyzed for total phosphorus, total nitrogen, and chlorophyll a. Samples for total suspended solids, total nonvolatile suspended solids, and fecal coliform bacteria were also collected from selected lakes. Carlson′s Trophic State Index (1977) was calculated for volunteer-collected Secchi depth data and Ecology-collected phosphorus and chlorophyll a data. Trophic state estimations based on these calculations and an evaluation of other data were assigned to a total of 73 lakes: 32 lakes were oligotrophic or oligo-mesotrophic, 26 lakes were mesotrophic or meso-eutrophic, 14 lakes were eutrophic, and one lake was hyper-eutrophic. Statistical trend in water clarity was evaluated for 29 lakes that were monitored by volunteers for at least five consecutive years. Using the seasonal Kendall test for trend, ten lakes exhibited statistically significant increasing trend in water clarity, and five lakes exhibited statistically significant decreasing trend in water clarity. For many of the monitored lakes, water clarity was better in 1994 than during previous years, which appears to be reflected in the results of trend analysis. This report includes a compilation of the 73 lake assessments (reports) which were written in laypersons′ terms and include data results from 1994. |
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