A Water Advisory Here Is Normal, Not an Emergency. Check It Anyway

Visitors to this coast are often startled by the phrase water-contact advisory, because it sounds like a crisis. On the Mississippi Sound it is closer to a tide table: a routine, published condition that varies by beach segment and usually follows heavy rain.

What causes one

The Sound is shallow and it receives drainage from a large area. When heavy rain falls, runoff carries bacteria into the water, and levels can rise sharply for a day or two before falling again. The state's environmental agency samples the beaches through the season and issues an advisory when a sample exceeds the standard for contact with the water.

An advisory does not close a beach. The sand stays open, and walking, sunbathing, fishing and boating are unaffected. What it advises against is swimming and putting your head under.

How to use them

• Check by segment, not by coast. Advisories are issued for individual stretches. One beach can be under advisory while the next one along is clear.
• Check the morning you plan to swim. They lift as quickly as they appear.
• Assume a couple of days after any heavy rain. That is the pattern here.
• Do not rely on the sand to tell you. The posting is published, and a sign may or may not be at the access you are using.

The exceptional year

In 2019 this went well beyond routine. Prolonged openings of the Bonnet Carre Spillway upstream diverted an enormous volume of Mississippi River freshwater into the Sound over a record 123 days. The harvestable oyster reefs died, an algal bloom spread, and all twenty-one Mississippi beaches were closed to water contact in June of that year.

That was not a normal season, and nothing like it has happened since. It is worth knowing about because it explains why people here talk about the river when they talk about the beach, and why the advisory system is taken seriously rather than shrugged at.

If you want water with none of this attached, the answer is the same as always on this coast: get on the ferry to Ship Island and swim on the Gulf side.