Authorities are urging swimmers and surfers to exercise extreme caution after days of heavy rainfall created murky, debris-filled waters along the coast of Sydney and across much of New South Wales.
The state government warning follows a significant deluge that has washed sediment, stormwater runoff, and organic matter into coastal areas and estuaries. Experts say these conditions dramatically reduce underwater visibility — creating what marine biologists describe as “prime hunting conditions” for bull sharks.
Bull sharks are known for their ability to tolerate both saltwater and freshwater, often traveling up rivers and into estuarine systems after heavy rain. The murky water not only provides them with easier concealment but can also draw in baitfish and other prey species flushed out by floodwaters. Increased food activity, combined with low visibility, can heighten the risk of accidental encounters with humans.
Authorities stress that shark behavior is not necessarily more aggressive during these periods — but the environmental factors can increase the likelihood of sharks being closer to shore and less able to distinguish between prey and people in the water.
Beachgoers are being advised to:

• Avoid swimming in discolored or murky water

• Stay out of the ocean near river mouths and estuaries

• Refrain from swimming at dawn, dusk, or nighttime

• Avoid areas where baitfish are visible or birds are actively feeding

• Follow all posted beach closures and lifeguard instructions

Surf Life Saving officials have increased monitoring efforts and are working alongside marine authorities to track shark activity. Drone patrols and aerial surveillance may also be deployed in high-risk areas.
Heavy rainfall can also carry pollutants and bacteria into the ocean, prompting separate health warnings unrelated to sharks. Officials recommend checking local water quality advisories before entering the water, especially in the days immediately following major storms.
While shark sightings are not uncommon along Australia’s coastline, incidents remain statistically rare. Still, authorities emphasize that awareness is key — particularly when environmental conditions shift rapidly after severe weather events.
For now, officials are urging patience. As ocean conditions stabilize and sediment settles, visibility improves and shark activity typically returns to normal patterns. Until then, caution is the message of the day for anyone heading to the surf.