If you made plans to visit Blue Grotto in the next several days, you may need to change them. So, what happened?
First, the sun…
In early August, we were hit with something we never see when water levels are normal. This was an algae bloom. It caught us by surprise and still leaves us scratching our heads.
Fortunately, algae blooms at the Grotto are infrequent. If you’d like to know more about them, follow this link. Sunlight is the chief culprit, which is why algae blooms do not affect the cavern.
We feared this recent algae bloom might be with us for a while. At least we were until a week ago. Then, to paraphrase Forrest Gump, “And just like that, the visibility cleared up.”
We thought we were out of the woods. And then…
And then the rain…
Withing a few days, visibility in the Grotto was essentially back to normal. Several visitors characterized it as “excellent.” And then, while we slept, it rained and rained hard.
The rain succeeded in dislodging at least two veins of clay that had collected in what once had been solution tubes along the face of the cliff. This dumped several hundred pounds of clay directly into the open-water basin. And, unlike an algae bloom, which only affects open water, the clay silt appears to have permeated well into the cavern.
The worst sort of silt
Cave diving students learn about three types of silt.
- Sand is the most benign. It’s coarse and heavy and, if disturbed, will drop out of suspension right before your eyes.
- Mud is more concerning. It remains in suspension longer but usually clears up within a day.
- Clay is the worst. It can take several days for clay silt to drop out of suspension.
So, now what?
The following morning, visibility throughout the Grotto was less than four feet. As of now, it’s not improved more than a few inches.
You wouldn’t want to dive under these conditions and would certainly not want to subject students to them. Unless something dramatic happens, we expect to be closed until sometime next week at the soonest.
All we can do at this point is keep prospective visitors informed. We’ll do this through our website and Facebook. As soon as we can re-open, we will let everyone know.
In the meantime, we will just have to sit tight and let nature do its thing. It is, at the very least, a learning process.