A good downpour is welcome in Kuwait, but the sea you find the next morning is not the one you left last week. Within hours the water turns the colour of wet cement, a scum line forms along the shore, and the smell near the outfalls changes. Knowing what is happening is the difference between a wasted trip and a smart one.
Rain falls faster than the ground can absorb it. Asphalt sheds everything, so water runs across streets, car parks and industrial areas, picking up whatever it passes. It reaches the sea through storm drains that discharge straight onto the coast, often a few hundred metres from where boats are launched. Fresh and slightly lighter, that runoff spreads as a surface layer and hugs the shore instead of mixing away. Hence the brown band on the beach while the water further out looks clean.
The colour is the least of your problems; the debris is the real hazard. After a heavy fall you get plastic bags, foam boxes, timber, palm fronds and reeds moving with the current and settling in channels. Timber is worse than bags because it sits just under the surface and finds your propeller before you see it. Weed piles up faster too, and a length of it around a prop will stop you dead.
Murky water cuts underwater visibility hard, which matters for spearfishing and diving. For line fishing the issue is not only sight: runoff shifts salinity and temperature in the shallow band along the shore, and fish move out of that zone for a while. Work deeper water or head away from the outfall, and give it a day or two. Log what you catch and where, so after a couple of seasons you know which marks recover fast. The B7R app has a catch log that keeps that record with date and location.
There is no fixed number. Shallow, enclosed water holds the mess longer; an open shore with wind and tide flushes faster. Expect a day to three days after the last rain, longer after a heavy fall. Recovery shows: the brown line pulls off the beach, the smell fades, colour returns. Check sea state and wind in the B7R app before you go, because a strong northerly stirs everything up again and stretches the process out. Tide matters too, since water sitting over the flats clears far more slowly than open water.
Treat water near an outfall as not clean. Do not rinse food containers in it, do not swim at the drain mouth, and wash your hands and the kids' hands after a beach session. Clean any fish well away from the water, and wash the knife and board afterwards.
The short version: rain is no reason to rush. Wait a day, check the sea state, stay away from the outfalls, and rinse your gear when you get back. It gets easier when you know what you are looking at before you leave the dock. The app is free on Google Play, with tide times for Shuaiba and Shuwaikh, sea state, seasons and a fish guide. Download it here and plan your next trip.