4/13/2023 0 Comments Secchi disk graphBillings Middle School students currently collect Level I data dockside. Richard Fleming collected rainfall as part of that program. Gail Barker collected weather observations, secchi disk (water transparency), surface water temperature, and water surface elevation. Friends of Green Lake decided to make the standard Secchi measurements to record water clarity changes through the summer, and in the fall we also began measuring water temperature and the lake level. FOGL Monitoring Program Level Iĭuring the spring of 2003, while trying to gather information about the condition of the lake, FOGL learned that no agency was regularly monitoring the lake’s water clarity. A gauge on the dock near the boat rentals was installed in 2004 and helps monitor the lake’s water level.įriends of Green Lake members Gayle Garman and Richard Fleming take water samples and collect information on water conditions from two kayaks positioned side-by-side as part of the King County Lakes and Streams Monitoring Group (formerly Lake Stewarship Program). FOGL also helps track the water level of the lake. FOGL has requested monitoring of both East and West Green Lake Beach – the only public warm-water beaches in the city. The King County Lake Swimming Beach Monitoring Program page shows temperature and bacterial count charts and data for West Green Lake Beach only. Bacteria Counts West Green Lake Beach Bacteria Levels and Water Temperature Graphs and Data Water clarity in the late summer in 2008 was exceptionally high and we wait to see if the high clarity continues throughout 2009. The 2004 treatment continues to be effective at reducing phytoplankton blooms. The graph shows that water clarity improved following the alum treatment. 19 data show conditions before the alum treatment in 2004, and 2005 to 2009 data show conditions after the treatment. The goal of the alum treatment is to maintain a Secchi depth at more than 2.5 meters, year round.Ĭlick here* to see average Green Lake water clarity over the years. The 2004 treatment provided excess alum and the un-reacted alum settled to the bottom of the lake where it combines with phosphate escaping from the bottom sediments. Alum combines with phosphate and settles to the bottom, removing the phosphate from the water. In 2004, the City treated the lake with alum (aluminum sulphate) to reduce the amount of phosphates in the water and hence reduce plankton blooms. In the past, plankton blooms often reduced water clarity in the late summer to less than 3 feet. The Secchi depth of Green Lake varies throughout the year. Blue-green algal blooms caused the City Health Department to close Green Lake to swimming and boating in 1999, 2002, and 2003. On occasion, blue-green algae (a type of phytoplankton) can grow to great density and may become a health risk. High levels of phytoplankton can lead to unpleasant odors and scum. Shallow Secchi Disk measurements indicate high levels of sediment (caused by surface runoff following storms) or high levels of phytoplankton (caused by warm water temperatures, sunlight, and nutrients). The distance at which it disappears is a measure of water clarity. The disk is lowered into the water until it disappears. Green Lake water clarity varies with the amount of suspended sediment (clays and silts) and/or plankton (microscopic plants and animals also known as algae) in the water.Ī Secchi Disk about the size of a dinner plate is used to measure water clarity. Management goal is an average summer depth of 2.5 meters or 8 feet. To measure water clarity, a Secchi Disk about the size of a dinner plate is lowered into the water until it disappears.
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