Global Water Samplers SS201 are being used to collect first flush and composite samples.  The samplers on the river, at sites 1 and 2, are collecting a 48 hour composite sample.  The 48 hour time period was determined by analyzing typical storm event hydrographs at the USGS monitoring station downstream of our study area.  A 3 hour composite sample is being collected at the storm water pond discharge at site 5.

Samplers are set to launch when the river rises 1/2-inch.  A sensor is placed in a stilling well 1/2-inch above the water level.  The level of this sensor is checked and adjusted bi-weekly at a minimum as water level fluctuates.  Once the first flush sample is ready, City staff remove the first flush bottle and replace it with an ice bottle to keep the composite sample cool while it continues to fill.  Depending on temperature the ice bottle may need to be replaced numerous times in the 48 hour filling period.  The first flush is kept in a refrigerator until the composite samples are ready.  Once the composite sample is completed, all samples are then transferred to a lab for analysis as soon as possible. 

When the sample bottles need cleaning, they are rinsed out with hot water and a stiff bristle brush.  They are then put in the dishwasher with a phosphorus free detergent.  Then rinsed 2-3 times with distilled water.