The Ledger Podcast · S2 E1
Green water: what the August bloom tells us
The harbor turned green for eleven days. A water chemist explains where the algae came from and why it may come back.
- Host
- Mara Okafor
- Reporter
- Ines Lindqvist
- Guest
- Dr. Anneke VisserWater chemist, East Bay Marine Lab
The harbor turned green for eleven days in August. Mara Okafor and Ines Lindqvist talk to a water chemist about where the algae came from, and whether it will happen again next summer.
Topics in this episode:
- What kind of algae caused the bloom, and whether it was toxic
- The role of upstream fertilizer runoff and a wet July
- What the East Bay Marine Lab is watching for next summer
Dr. Visser's lab publishes weekly water readings at eastbaymarinelab.example.org.
Transcript
Ines Lindqvist: Dr. Visser, when people saw the harbor turn green, the first question was whether it was safe to be near the water. What did your testing show?
Anneke Visser: It was a bloom of Microcystis, a cyanobacteria that can produce toxins, but our readings during those eleven days stayed under the threshold where we'd advise against contact. We still told people to keep pets out of the water, because dogs are more sensitive than people.
Mara Okafor: Where did it come from? The harbor doesn't usually turn that color.
Anneke Visser: Two things stacked on top of each other. A wet July pushed more runoff than usual down the river, carrying fertilizer from farms upstream. Then we had ten straight days over 90 degrees. Warm, nutrient-rich water is exactly what that algae wants.
Ines Lindqvist: Is this new, or has it happened before and we didn't notice?
Anneke Visser: We've seen small blooms before, a day or two, gone before most people noticed. Eleven days is new for this harbor. That's the part that worries me more than the color.
Mara Okafor: Could it come back next summer?
Anneke Visser: If we get another wet spring followed by a heat wave, yes. The lab is putting sensors upstream this winter so we get earlier warning next time, rather than waiting until the water's already green.
Ines Lindqvist: Anything residents can do?
Anneke Visser: Less fertilizer on home lawns near storm drains helps more than people think. It's a small piece next to the farms upstream, but it adds up across a whole city.
Mara Okafor: We'll link your lab's weekly readings in the show notes so people can check the water themselves.
Anneke Visser: Please do. We post them every Monday, bloom or no bloom.