Hour zero to day three.
What to do, in what order, with what you already have on site. The clock starts when somebody tells you the water looks wrong.
Three days is the useful window. Most of what you can influence happens inside it, most of what goes wrong afterwards was set in motion during it, and by the end of it you either have a plan or you have an incident.
What follows is a sequence, not a regulation. Your permits, your regulator's standing conditions and your own written procedures come first, always. Where this conflicts with them, they win.
The sequence
Six blocks, each ending in something written down.
- Hour zero — the report arrives Somebody has seen something. A colour, a smell, a foam line, fish behaving oddly, a pressure trend that is not the usual one. Log the time and the name of the person reporting before you do anything else, because the timeline is the thing you will be asked for later and it cannot be reconstructed afterwards.
- Hour zero to one — fix the facts A sample, a position, a photograph with the horizon in it, and a reading of whatever you routinely measure. Two bottles if you have them: one to the laboratory, one in the fridge. The second bottle costs nothing and settles arguments that start on day nine.
- Hour one to four — reversible moves only Anything you can undo before lunch, do now. Draw from a different depth. Ease the abstraction rate. Start supplementary aeration. Hold the feed. Move outdoor staff upwind. Do not yet take a decision that costs a harvest or a season.
- Hour four to twelve — the calls Regulator, laboratory, insurer, and anyone whose water you share. This is also the hour to open a conversation with a treatment provider, because mobilisation is measured in days and the call is free. If a treatment programme is already running on your water, the institution independently monitoring it goes on the same list — it should be seeing your feed anyway, and it will be asked later what it saw. A short holding statement goes to staff now, whether or not the public one is ready.
- Day two — the night is the event Bloom material that dies decomposes, and decomposition consumes oxygen in exactly the water that has least to spare. The worst readings usually arrive between two and six in the morning. Staff the night. Take readings through depth rather than at the surface, and take them at the same places every time so the numbers mean something.
- Day three — decide what kind of event this is Passing, settled, or worsening. Passing means hold the watch and stand down against criteria. Settled means move from improvisation to a rota, a supply list and a treatment decision. Worsening means the escalation you have been putting off, and it is better taken on day three than on day six.
Triggers
If you see this, do this, tell that person.
Fill in your own numbers in the left column before the season. The value of the table is that somebody at three in the morning does not have to invent the middle two.
| Observation | First move | Who is told | Reversible |
|---|---|---|---|
| Discoloured water near the intake | Sample and photograph; pull the screen differential trend for the last week | Duty manager | Yes |
| Screen differential climbing | Reduce rate before quality degrades; check the alternate depth or source | Plant manager; regulator if abstraction changes | Yes |
| Oxygen below your night threshold | Supplementary aeration; hold feed; increase reading frequency | Site manager | Yes |
| Fish at the surface at first light | Stop feeding; prepare the emergency-harvest decision but do not take it yet | Site manager; veterinary adviser; buyer | Partly |
| Airway irritation among staff | Move staff upwind or indoors, asthmatic staff first; log it as an occupational exposure; review beach and pontoon opening | Duty manager; occupational health; health authority | The move is. The exposure is not — see the panel below |
| Dead fish in an enclosed basin | Recover and remove before decomposition loads the water — but not by improvisation. Decomposing biomass and disturbed anoxic sediment release hydrogen sulphide, so this is a planned job with gas monitoring, the right protection and a lawful disposal route | Harbourmaster; municipality; whoever holds your confined-space and waste duties | No, and it gets worse hourly — which is an argument for a standing contract, not for sending your own staff out at midnight |
On aerosol exposure — read this before you write your own trigger
Moving people out of the aerosol is the right first move. It is not a cure, and the published record will not support treating it as one.
Fleming and colleagues, working on Florida Karenia brevis aerosols, recorded statistically significant increases in reported respiratory symptoms in people with asthma after a single hour on an affected beach — and note that asthmatic subjects have reported symptoms lasting up to at least five days after that one hour. The same body of work links active red tides to raised coastal emergency admissions for asthma, pneumonia and bronchitis. Detectable lung-function changes may be delayed by hours or days, so a normal reading at the end of a shift proves very little.
What that means on a site. Exposure of staff is occupational, so it goes into the accident book and through whatever occupational-health route your jurisdiction requires — not into a supervisor's memory. Anyone with asthma comes off the exposed area first and does not go back on it because they feel better. A worker who is still symptomatic at the end of a shift gets referred, not reassured.
Source: Fleming and colleagues, Environmental Health Perspectives, 2009, via PubMed Central. It describes brevetoxin-producing species and must not be generalised to other toxin classes.
Communications
Four audiences, and only one of them can wait.
One caveat before the order, and it outranks the order. If your permit, your abstraction licence or your national regulations set an immediate notification duty, that call is first and nothing on this page changes it. A statutory clock does not pause while you brief a shift.
Staff next. Their exposure is occupational, they will be asked by customers within the hour, and a team that hears it from a guest stops trusting the desk.
Regulator second where no immediate duty applies, in the form and timescale your permit specifies. An early, incomplete notification is almost always better received than a complete one that arrives after somebody else has reported it.
Customers and the public third, with a statement that says what is known, what is not, and when the next update comes. Give a time and keep it. That single habit does more for a site's reputation through an event than any amount of careful wording.
Head office last, and this is deliberate. The first three have decisions to take. The fourth mostly has questions, and answering them at hour two is how sites lose the morning.
Asked on the phone, usually at speed
Five questions from the duty desk
How long does a bloom usually last?
There is no useful average. Events run from a few days to several months depending on species, nutrient supply, wind and how quickly the water body exchanges.
The 2008–09 event in the Arabian Gulf and Oman Sea ran from October into the middle of January. Build the rota for weeks. Be relieved if it turns out to be days.
Should we harvest the pen early?
It is the most expensive reversible decision on the site, which is exactly why it needs a written trigger rather than a judgement at dawn.
The inputs are your own oxygen record through depth, fish behaviour, the market you can actually reach at short notice, and how much of the year's volume is sitting in that pen. Set the trigger in the winter, when the answer costs nothing.
Can we simply wait it out?
Sometimes. It is a legitimate plan where the asset can absorb the loss and the exposure is short.
It stops being legitimate at a drinking-water intake, wherever staff or the public are in the aerosol, and whenever a die-off is about to load an enclosed basin with decomposing material. The oxygen crash after a bloom has killed more stock than the bloom itself in plenty of documented events.
At what point is in-water treatment worth calling for?
Earlier than most sites call, and the reason is logistics rather than biology. A vessel has to be routed, permitted and mobilised.
A call placed when the event is confirmed buys days that a call placed at the point of loss does not. And if the answer is that treatment is not the right tool for that water, that is a useful thing to hear on day one rather than day nine.
Do we tell guests before we have a laboratory result?
You tell people what you know, when you know it, and you say plainly what you do not yet know.
Staff are told immediately; their exposure is occupational. Guests are told before they work it out for themselves, which they will, from the smell if nothing else. A holding statement drafted in the calm beats an accurate one drafted at midnight.
Sources cited on this page
- Peer-reviewed respiratory and toxicology literature via PubMed Central — aerosolised brevetoxin exposure and upper-respiratory response.
- Estuaries and Coasts, Springer, 2013 — the 2008–09 Cochlodinium polykrikoides bloom in the Arabian Gulf and Gulf of Oman.
- Alarivean, Inc. — mitigation and remediation solutions, for the treatment side of an event.
Before the next one
Get the call out of the way early.
Send the asset, the months it goes wrong and the worst event you have had. Alarivean answers with what mobilisation to your water would actually involve, so the number on your laminated card is a real one.