How are humans affecting the water quality in Tillamook Bay?

This might sound like a simple question, but studies have been going on for decades and there is still ongoing research working to answer it. Tillamook Bay is a great habitat for oyster aquaculture, and it also happens to be in a valley largely occupied by dairy farming. In fact, there are more cows than people in the city of Tillamook. This makes monitoring the water quality and important, but complex, task. The EPA at Hatfield has been working on this current research study since 2016, which includes many projects working from various angles to try to understand the whole picture of the water chemistry in the Tillamook Bay.

One of the longest-running projects is monitoring the water quality in the bay. Multiple different devices are being left in the water for months at a time to take continual measurements of water quality. These include a Sea-Fox, Sea-FET, and a Multi-Parameter Water Quality Data Sonde. These instruments provide long-term measurements of pH, chlorophyll, salinity, depth, temperature, and dissolved oxygen. This is not one of my specific projects, but I still got to tag along while the instruments were deployed to learn about the project.

Deploying instruments to measure water quality in the bay after they were briefly taken out for cleaning.

One project that I’m working on is looking at how the water chemistry in the Trask River changes over the course of a day. On June 27, we left a data sonde at two different locations along the Trask river to measure dissolved oxygen, pH, chlorophyll, temperature, and depth over a period of two days. On June 29, we left Newport at 5:30am to drive to Tillamook, and then we collected water at 4 locations along the Trask River at five different times throughout the day. These water samples will be measured for nutrients and carbon, since these measurements can’t be taken with a data sonde. At the end of the day, we collected the data sondes left on June 27 and took them back to the lab along with the samples. These measurements will allow us to get an idea of how the chemistry of the water changes throughout the course of the day so that we can account for this when we compare the levels of carbon and oxygen in other streams. It is likely that we will return to get measurements from a longer time span that includes the evening and night.

Left: Getting set up to leave a YSI data sonde overnight in the Trask River. Right: Preparing water samples from the Trask River to be stored. Water samples for carbonate are put in glass bottles and then poisoned with very small amount of mercuric chloride to prevent further changes to the carbon composition; samples for nutrients are filtered and stored on ice.

Another part of the picture is looking at in-stream processing from periphyton, which are the algae and other organisms attached to the rocks at the bottom of the river. We know that land runoff has a significant effect on the water chemistry, but we have not yet looked at the biological processes in the stream itself. So, how do you measure exactly the amount of respiration occurring from the slimy periphyton on river rocks? It took some pondering, but we decided to take all the rocks from a given area and place them in sealed container in the river, while measuring the amount of dissolved oxygen in the water. The challenge is, all the containers that are able to seal around the oxygen probe have an opening that is too small to fit rocks. The solution? Find a new container. So, we took a trip to the Smart Foodservice Warehouse Store, where there are containers of all shapes and sizes to choose from, and got a few weird looks as we measured and puzzled over containers in the food storage aisle. It’s still a work in progress, but we’re getting closer to setting up this portion of the study.

Searching for a container to measure periphyton respiration at the Smart Foodservice Warehouse Store.

When I’m not in the field, I’m measuring the nitrogen and carbon samples in the lab. The EPA just got a new machine for measuring dissolved CO₂ and total CO₂ called the Burkolator, developed by Burke Hales at OSU in Corvallis. It is one of only 20 or so in the world, and he came to Newport to teach us how to use it. As you can see, there are a lot of tubes; not shown in the photo is the computer screen used to control everything. I’ve been spending a lot of time learning how to work the machine and developing a written set of instructions, which is a fun challenge. We’re hoping to get some of my samples running as soon as Tuesday, July 10!

Learning how to use the Burkolator.

Like I mentioned, there are a lot of projects going on to answer the big overarching question! I have only gotten started on some parts of my project; there will be more to come. My work for the summer is only a small piece of the large overall study, but I am excited to be contributing to our understanding of the bay and to have the opportunity to learn about the diverse array of other projects happening at the same time.