The "My River POV" series provides readers the opportunity to learn about the unique insight and experiences of the San Antonio River Authority (River Authority) staff and their personal connection to the San Antonio River in hopes of inspiring stewardship of area creeks and rivers. In honor of The International Day of Women & Girls in Science, we are delighted to feature water quality scientist Michiko Daniels!
Michiko Daniels, Water Quality Scientist
Ever since I moved to San Antonio in 2007, I've enjoyed walking to the headwaters of the San Antonio River, the Blue Hole. When I first visited and peered into the spring, I saw tiny Mexican tetra fish pushed by water moving side to side and flowing upwards. When my daughter was young, I used to take her and her friends to the spring to see if there was a flow and look for fish. My favorite part of the Blue Hole is that the water coming from the Edwards Aquifer naturally turns aquamarine under the bright sunshine.
Spending time at the Blue Hole, one of the many springs that form the headwaters of the San Antonio River.
As the river travels down to Brackenridge Park, the water appears dark green. The green plants that fish and ducks swim among are algae. Did you know that most algae are harmless? In fact, it is an important food and habitat source for fish and other aquatic life. However, in summer especially, the algae can grow explosively. After algae die, the microbes in the river decompose them by stealing oxygen. This results in decreased levels of oxygen for the fish and freshwater mussels. In general, aquatic organisms have only 0.001% availability of dissolved oxygen to live while people have 21% oxygen in the air. Because a slight change in the oxygen level in the water can kill many fish, it is critical to monitor the overgrowth of algae. It's one of the many important things I watch out for as a water quality scientist. It's also a crucial part of fulfilling the CLEAN aspect of River Authority's mission which is committed to safe, clean, and enjoyable creeks and rivers.
An algal bloom in the San Antonio River.
How do you measure algae levels in the laboratory?
In the laboratory, I analyze Chlorophyll-a, a pigment that makes algae and plants green. By measuring the pigment, we can tell if the river has too much algae or not. The process of Chlorophyll-a analysis is somewhat similar to brewing coffee. Unlike brewing coffee, my interest is in the grounds, not the coffee. In the Chlorophyll-a test, river water is poured into a funnel with a paper filter. The paper catches the green pigment. Then, this pigment is ground and extracted in a special liquid for the instrument analysis. This process must be carried out under dim light as the green pigment degrades when exposed to light and heat.
Michiko filters river water samples for Chlorophyll-a analysis.
The 2021 Basin Highlight Report shows that the Chlorophyll-a level in some segments of the San Antonio River is high, indicating potential algal overgrowth and water quality issues. Whenever you walk or paddle along the river, you can look for any indication of excessive algae growth, especially in summer. If you happen to see this growth, along with multiple dead fish, please report it to the River Authority’s environmental investigators. Our team will investigate by measuring the oxygen level in the water and collecting the samples for any high-level chemicals. Let's watch out together for the health of area creeks and the San Antonio River and keep the San Antonio River Basin’s aquatic communities thriving!