Buoy Specifications
Profiling platforms are located on Lake Washington and Lake Sammamish (one on each lake). Each profiler is equipped with a sonde that measures water depth, temperature, specific conductance, dissolved oxygen, turbidity, pH, and fluorescence-derived chlorophyll (total algae) and blue green algae (BGA) concentrations. Since 2017, King County has employed YSI EXO2 sondes for water quality profiling. Prior to 2017, YSI 6600 V2 multi-parameter sondes were used.
Each platform is also equipped with a weather station that monitors air temperature, relative humidity, solar radiation, and wind speed and direction. Each platform consists of a 4x8-ft raft with 1,000 pounds of net buoyance and one ballast weight. The profiling equipment consists of two 30 watt solar panels; winch controller, assembly and profiling cable; data logger and communication antenna; and weather station mounted on a mast. The total height of the platform is about 3 m (~10 ft) and it is lighted with a Coast Guard compliant beacon (155M Amber Flasher-Changer). A single mooring line and anchor are used to secure the system on station.
Profiling frequency is limited by the amount of available solar power, resulting in no more than six profiles per day during spring, summer and fall and only three profiles per day during winter. Data are transmitted in near-real time via modem to a King County data server. Details regarding the operation and maintenance of the system can be found here.
Profiling Sonde Specifications
| Parameter | Range | Resolution | Accuracy |
|---|---|---|---|
| Depth (m) | 0 to 100 | 0.001 | ± 0.13 |
| Temperature (°C) | -5 to 50 | 0.001 | ± 0.01 |
| Specific Conductance (mS/cm) | 0 to mS/cm | 0.001 to 0.1 | ± 0.5% of reading |
| Dissolved Oxygen (mg/L) | 0 to 50 | 0.01 | ± 0.1 mg/L or 1%, whichever is greater |
| Turbidity (NTU) | 0 to 4000 | 0.01 | 0.3 NTU or 2%, whichever is greater |
| pH | 0 to 14 | 0.01 | ± 0.2 |
| Chlorophyll (µg/L) | 0 to 400 | 0.01 | ~ 0.1 µg/L detection limit |
| Blue-Green Algae (µg/L) | 0 to 280 | 0.01 | ~ 0.1 µg/L detection limit |
Weather Station
| Parameter | Range | Resolution | Accuracy |
|---|---|---|---|
| Wind Direction (degrees) | 0 to 360 | 1 | ± 3° |
| Wind Speed (m/sec) | 0 to 60 | 0.1 | ± 0.3 or ± 3 % |
| Wind Speed (m/sec) | 0 to 60 | 0.1 | ± 0.3 or ± 3 % |
| Air Temperature (°C) | -60 to 140 | 0.1 | ± 0.3 |
| Pressure (in Hg) | 17.7 to 32.5 | 0.01 | ± 0.015 |
| Relative Humidity (%) | 0 to 100 | 0.1 | ± 5% |
| Total Solar Radiation (watt/m²) | 0 to 3000 | 1 | ± 5% |