Usually, when people flock to Galveston beaches in the Spring and Memorial Day weekend, they're treated to murky brown water. But last weekend, beachgoers were surprised to find themselves splashing through clean, bright blue waves on a number of Gulf beaches. This was no hoax, either—the clear water came from a change in wind and current patterns.

Typically, winds from the south and southwest push the silty river water that drains from the Mississippi and Sabine rivers into the Gulf of Mexico along Texas' coastline, making it muddy. But during this recent shift in weather conditions, the prevailing current went north instead, carrying less sediment into the gulf. That, combined with a reduction in the flow of muddy river water caused by a lack of rain (meaning there was almost no runoff from area rivers) resulted in sparklingly blue beach water on some Gulf beaches.

The beautiful water was short-lived, though. By Wednesday, the beach water was back to its normal muddy brown state.

While the muddy, brown color of coastal water has nothing to do with pollution from oil drilling or other sources, it does have to do with how shallow the ocean is in this region. This makes it hard to circulate freshwater from the surface, so it tends to sit on top of salty seawater.

The good news is that despite the sometimes ugly brown hue of Gulf water, the water is safe to swim in. The beaches are constantly tested by the Galveston County Public Health Laboratory to make sure bacteria levels remain below harmful amounts.