There are definitely some essential tools of the trade for our Water Quality team’s variable work. There are at least three visible in the photo above (hint: the grey device is not a GPS). Think you know?
Answers: A Sonde, the Multi-parameter Display System that translates data from the Sonde, and a Jon boat! If you answered hats, motors, water, sunglasses, sunscreen and nearby personal floatation devices, you are also correct, but let’s talk a little more about the technical side of things!
RWMWD monitors many different sites and bodies of water throughout our District.
Lakes, streams, ponds, rain gardens, tree trenches and green roofs are just a few of things we monitor. Depending on the site, there are a whole bunch of different parameters we try to look at to help determine what is going on. It could be something as simple as finding the depth of water in a rain garden throughout a storm event or as complex as figuring out concentrations of dissolved oxygen, conductivity or heavy metals in storm water to name a few.
A wide variety of District projects, studies, and sites requires a wide variety of equipment and instrumentation. Below is a brief summary of some of the equipment the Water Quality program uses around the District.
Orpheus Mini – This is a pressure transducer used to monitor water levels at our office site as well at water levels in the tree trenches at Maplewood Mall. There are really two parts to this piece of equipment: 1 – the pressure transducer that actually sits in the water itself and 2- the data logger which is the “brains” and is where all the programing is done. The data logger stores the information gathered from the pressure transducer.
Thalimedes – This is a weight, bobber, and pulley system used to measure water levels in rain gardens. It helps calculate how fast rain gardens drain. These units are generally placed in a protected metal or PVC tube that lets water in. As the rain garden fills with water it will raise the yellow float. That level is then recorded in the data logger. As the water soaks into the ground, the yellow float will lower. The amount it goes down over time is an important indicator of how ‘healthy’ a rain garden is.
750 Area Velocity modules – The District uses this type of probe/sensor in all of its monitored storm water pipes. This probe measures the average velocity in the stream flow though ‘patented’ Doppler technology. There is also a pressure transducer that can measure the depth of water. The ISCO 6700 series sampler then calculates the flow based on pipe size, water level and water velocity.
730 Bubblers modules – RWMWD uses a bubbler set-up in steams, holding ponds or in areas that always hold some level of water. Within the 730, there is an internal air compressor that forces air through a ‘bubble line’ (think aquarium hose) that is placed and anchored in the water. By measuring the pressure needed to force air bubbles out of the line, the ISCO 6700 sampler can calculate the water level.
Secchi Disk – This tool measures water clarity in lakes and ponds. This is done by lowering the secchi disk into the water column until it cannot be seen. We then raise the secchi disk so it can just barely be seen in the water. That depth is then recorded and a measurement of water clarity has been taken.
If you can imagine, this list contains just a few of the many tools that our Water Quality staff use to monitor our lakes, ponds, streams, rain gardens, Best Management Practices (BMPs) and more. We’re glad to have Eric, Dave, and Wyatt, our summer intern, on staff to manage and maintain all of this equipment and data!