
Individual storm events in Kingsbury Creek are monitored using an automated water sampler (made by ISCO). The sampler is triggered by increasing water levels, and collects a water sample every hour during a storm event. |
Stream Monitoring
Units (SMUs)
There are essentially four components
to each of our SMUs; the water quality sensors, the data loggers,
the modem for transmitting data back to the lab, and a power
source.
The unit on Kingsbury Creek has these plus an automated water
sampler that collects water from the stream whenever the stream
reaches a preset minimum depth.
Water quality sensors for stream depth,
specific conductivity (EC 25), and turbidity are on a Yellow
Springs Instrument (YSI) 6900 series sonde (Chester and Tischer)
or a 6820 sonde (Kingsbury). The image below shows the probes
mounted on the end of a sonde.
Go
to the Water Quality
Primer to learn more about how these probes work and how
we use the data collected by the sondes.
The probes are set to measure each parameter every 15 minutes.
The information is then recorded either within the sonde
itself
or sent via a cable to the Isco sampler. This is the data
logging step. A modem is then used to
get
the data to the Duluth Streams computer. We usually call
the SMUs weekly to download the data but we also have the
ability to see the data real-time.
The
sonde is protected from rocks and other debris by a PVC housing
strapped to a cement block
that holds the unit in place on the stream bottom.
Of course we need electricity to run the entire operation.
The Kingsbury SMU is powered by a 12 volt battery that needs
to be replaced with a fully charged battery every two weeks
or so. The Tischer and Chester Creek SMUs are also battery
charged but the batteries are recharged automatically by
small solar panels. The St. Louis River SMU has a different configuration. For
more information and photos of the installation near the
Duluth lift bridge go to the Water on the Web St
Louis River page. |