Why is Myrtle Beach water brown?

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Key Points

Tannins (chemicals in decaying plants) stain the water brown. Sediment in the water also contributes to the brown color.
Runoff from human activity and algal blooms can turn the water brown.
The water is more brown in the summer, when temperatures are warmer and there is more rainfall.

Myrtle Beach, with its stunning coastline and sandy shores, is a popular destination for beachgoers seeking sun, surf, and relaxation. However, a common observation among visitors is the brown color of the ocean.

You may be wondering why. In this post, we’ll look at the top reasons the ocean here has a brownish color.

Recommended: Can You Swim in the Water at Myrtle Beach?


One primary factor influencing the color of the water is the presence of tannins. Tannins are organic compounds found in decaying plant matter, such as leaves, roots, and bark, which leach into the water. 

Myrtle Beach is surrounded by a vast expanse of coastal marshes, where the intricate ecosystem includes dense vegetation and a continuous cycle of plant life. As leaves fall and decay, tannins are released, giving the water a distinct brownish tint. 

Tannins are usually more concentrated after a heavy rain, which washes all that plant matter into the ocean.

Check out this article, for example, where the ocean turning brown was possibly attributed to tannins.


Another significant contributor to the brown coloration is the presence of suspended particles and sediment. Myrtle Beach is situated in an area with extensive river systems, including the Waccamaw River and the Intracoastal Waterway. 

These rivers transport sediment, minerals, and other particulate matter into the ocean. When these particles are suspended in the water, they scatter and absorb sunlight, creating a murky appearance.

During periods of increased river flow, such as after storms or heavy rains, the influx of sediment becomes more prominent, intensifying the brownish color of the water.

Human Activity

Human activities also play a role in the water’s appearance. Runoff from urban areas, construction sites, and agricultural activities can introduce pollutants and sediments into the water. 

Stormwater drainage, in particular, can carry debris, chemicals, and soil into nearby water bodies, affecting their clarity and color. 

Myrtle Beach’s popularity as a tourist destination and its urban development contribute to increased human impact on the coastal environment.


Algal blooms, a natural and sometimes seasonal occurrence, play a role in shaping the visual aspect of Myrtle Beach’s coastal waters. These blooms are the result of increased concentrations of microscopic algae, often fueled by warmer temperatures and nutrient availability in the water. 

While the presence of algae itself may not directly cause the brown color commonly observed at Myrtle Beach, it can contribute to a greenish tint, particularly during periods of heightened growth known as algal blooms. 

These blooms are a dynamic aspect of coastal ecosystems and can be influenced by factors such as nutrient levels, water temperature, and sunlight. 

Though some algae are essential to marine ecosystems as a primary source of energy, excessive growth and algal blooms can have ecological consequences, affecting water clarity and potentially leading to oxygen depletion in the water.

The Seasons

Lastly, seasonal changes affect the color of Myrtle Beach’s waters. 

In the warmer months, higher temperatures can enhance the growth of microscopic algae. Warmer temperatures can also impact the behavior of dissolved oxygen in the water, affecting its transparency.

Myrtle Beach Monthly Rainfall

Lastly, increased rainfall during certain times of the year, especially July, August, and September, can increase runoff and make the brownish color stronger.

Here is a chart of the average rainfall for each month at Myrtle Beach. Note that the highest amount of rain typically occurs during peak tourist season.

Average precipitation (rain/snow) in Myrtle Beach, the United States of America

Myrtle Beach Ocean can be Blue

Myrtle Beach got a great surprise in 2023, when it was blessed with turquoise waters you would typically only find in tropical areas.

The Atlantic Ocean was especially calm, preventing the ocean from stirring up the phytoplankton and sediment. That kept the ocean looking clear and gave both visitors and locals a wonderful surprise.

If you’re looking for a place to stay, check out Hotels Near the Convention Center. If you’re traveling with kids, you may like staying somewhere with an Indoor Water Park.

The Bottom Line

Despite its unique color, the brown water of Myrtle Beach is not harmful to beachgoers and swimmers. The area is known for its commitment to environmental preservation and water quality monitoring, and it is typically safe to swim in the ocean

Local authorities work diligently to maintain the health of the coastal ecosystem and address potential concerns related to water quality. Regular testing ensures that the water remains safe for swimming and other recreational activities.


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