Why Is the Visibility So Bad This Week? Reading the Pier Cam in Late August

A group member watching the pier cam this week sent in a fair question: 'Does anyone know why it's so particularly bad this week?' If you have been staring at green, stirred-up water and wondering what happened, you are not imagining it. The short version: this is not one problem, it is three late-summer factors stacking up at once - a lingering swell, a sudden upwelling flip, and the plankton bloom that upwelling feeds. Here is what is going on under that murk, and when it should clean up.

The short answer

Visibility is rarely killed by a single cause. This week it is a stack: leftover swell energy churning the shallows into a washing machine, a fast upwelling event that dropped water temps hard, and the green, plankton-rich water that upwelling feeds. Any one of those alone knocks a few feet off. All three together is why the shallows have been reading 5 to 10 feet of green haze while the surface still looks calm from the pier.

1. Lingering swell and surge

Swell does not have to be big to wreck viz. We have had 2 to 4 foot sets with residual, mixed-period energy grinding away all week, and a gentle long-period groundswell surges harder than the wave height suggests. That energy stirs sand and sediment off the bottom and keeps it suspended. Pier cameras sit in shallow water - roughly 13 feet at the end of most piers - which is exactly where surge is strongest. The rule divers repeat every summer holds: the shallower you are, the worse it looks. Right now it is common to see 5 to 10 feet in the shallows and 20 to 30 feet once you drop down the slope into deeper, calmer water.

2. An upwelling flip

The bigger story this week is temperature. Water that was sitting in the mid-70s a couple of weeks ago dropped into the high 50s and low 60s in a matter of days. That is upwelling - wind and current pulling cold, deep water up to the surface. It is great for feeding the food chain, but it does two things to visibility. First, the physical mixing suspends particulate. Second, that deep water arrives loaded with nutrients - and those nutrients are the real problem, as the next point explains. If you noticed the water go cold and green at the same time this week, that is no coincidence; it is the same event.

3. Green water is plankton

Those upwelled nutrients are jet fuel for phytoplankton. Late August already runs green along the Southern California coast, and a fresh nutrient pulse tips it into a full pea-soup bloom. The green tint you see on the pier cam is not dirt - it is billions of microscopic plants clouding the water column. Blooms come and go with the upwelling and the sun, which is why the water can look filthy one afternoon and noticeably better two days later.

Why the pier cam makes it look worse than it is

A pier cam is a short-range look at the single worst slice of the water column - the shallow, surgy, particulate-heavy top layer right off the sand. It is a useful gut check, not the whole picture. On the same day the cam shows a green murk layer, divers working the deeper reef or heading offshore to cleaner, current-fed water can find double or triple the visibility. Do not let one camera angle talk you out of a dive - check the deeper structure before you write off the day.

A live frame from the Scripps Pier underwater cam this week - green, hazy water with the pilings and kelp fading out fast. This is the shallow murk layer the cam is pointed at.

So when does it clean up?

This is a temporary, classic late-summer pattern, not a season-ender. It already started backing off midweek - as the swell eased, the shallows bumped from a few feet of murk up to 5 to 15 feet. Two things to watch: swell dropping below a couple of feet, and water temps ticking back up as the upwelling relaxes. When both happen together, the green thins and the shallows clear. Give it a few days.

How to still get a good dive this week

• Go deeper. Drop below the surge layer - the deeper reef and slope are holding far better viz than the shallows.

• Dive early. Get in before the afternoon wind builds and adds chop to the mix.

• Work protected pockets and headlands. Points like Point Loma can stay clean even in strong current - clean offshore water rides the current instead of muddying it.

• Time the tide. Several divers reported clearer water at high and slack tide this week; check the swings before you plan your entry.

• Check conditions before you drive. Our visibility tool at conditions.spearfactor.com reads live swell, temperature, and water-clarity data per spot, so you can skip the green days and pick the pockets that are actually diveable.

So no, you are not imagining it, and there is nothing wrong with the cam. It is late August doing exactly what late August does off Southern California: swell, upwelling, and a plankton bloom all showing up in the same week. Read the deeper water, time the swell drop, and it will come back - it always does.