Podcast: Local Meteorologist Deciphers the Colorful Coastline of Galveston Island

J.R. Shaw: Welcome to Galveston, unscripted. I'm your host, J.R. Shaw, in this episode. Today, I sat down with meteorologist Dr Hal Needham, a climate data scientist, to discuss Galveston's dynamic water color. As a Galvestonian, Dr Hal Needham is intimately familiar with Galveston's weather, climate, and surrounding bodies of water. Let's get into it.

Hal Needham: Yeah, so I'm Dr Hal Needham. I live here on the island. I'm an extreme weather and disaster scientist, Really focused first on the weather but more and more focused a lot more on Galveston Island. The people are amazing island here.

J.R. Shaw: I'm sitting down with you today to discuss Galveston's water color.

Hal Needham: It's kind of been a hot topic recently, oh, yeah, it seems like once or twice a year it becomes the thing everyone's talking about on social media.

J.R. Shaw: Yeah Well, could you go through the process on kind of why we have the water, the beach water that we have here?

Hal Needham: We have really dynamic water colors. You go out there for a walk, and at the beginning of your walk, it might look green. By the end, it might look blue brown or silver. The water color changes a lot around here. There are really two main reasons. One is a lot of it's locally generated. When we get winds kicking up, we get a lot of waves, and we have a really shallow sandy beach, so you get a lot of wave action. It just stirs up a lot of that sediment. But the thing to remember is the water color we see is really a natural color. It would have looked the same a thousand years ago. So we tend to get a lot of sand in the water when it gets windy and when we get waves.

I was just with Fox News a couple of weeks ago. They were down here on the island and I took a big glass mug and filled it with water. It looked brown at first. 10 seconds later the sand settled out and you saw mostly clear water with an inch of sand at the bottom. And that's really what it is. A lot of the time is just sand in the water.

J.R. Shaw: Where does that sediment come from? Where are we getting that?

Hal Needham: Yeah, so again, a lot of it's generated locally. The difference between a brown day and a blue day might be the local winds. But great question: where does the sand come from? To start with, in this area of the world, the Western Gulf, we have a lot of big rivers that impact us. So one of the biggest, and it surprises people, is the Mississippi River. They say that's 150 miles to the east. How does that influence us? There's an east-to-west current along the northern part of the Gulf, so a lot of that sediment that comes down from the Midwest, from the plains, the Mississippi River drains a lot of the continent is pushing a lot of that sediment into the Gulf. The east-to-west current can bring it all the way to Galveston Island. So the Mississippi River has a big impact, but also the Atchafalaya River in Louisiana, the Sabine River on the Texas-Louisiana border, the Brazos River, the Trinity, and Colorado, all these different rivers at some points of the year are dumping sediment into the Gulf. With the current, a lot of that sediment finds its way towards us.

J.R. Shaw: Galveston Island is a sandbar. Could we say that the reason Galveston Island is even here is because of that sand and sediment?

Hal Needham: We could absolutely say that, and that's a good point. When people complain about the water color, we wouldn't even be here if there wasn't sand in the water. If you go to parts of the Caribbean or even to the Florida Keys, people see this turquoise water, and wow, this is fantastic. Let's go to the beach, and you realize there aren't that many beaches. You go to parts of the Keys, and you might have to go three Keys over to find a little beach. Mostly, it's just coral sticking out of the turquoise water. They don't have a lot of rivers in the Caribbean. They don't have a lot of rivers in South Florida or the Florida Keys, so they don't have a lot of sand in the water. It gives them bluer water, but they don't have a lot of beaches.

So regionally, really, the two things are the locally generated winds, but then also what's going on with the rivers in the region, and that's why a lot of times we'll see a little bit darker waters in the spring and early summer. We know the spring can be a really rainy time here in the southeastern states, and the south-central states, and also, there's a lot of snowmelt. So again, the Mississippi is drawing from an enormous watershed that goes all the way from the Rocky Mountains to the Appalachian Mountains. So they're getting some of their highest water levels and discharge from the Mississippi in April and May, and so a lot of that sediment is getting out there in the Gulf. By the time you get to late summer or early fall, the region tends to be drier, the rivers are lower, and we tend to see more blue water days.

J.R. Shaw: So we can really thank some of that rain and snow melt in the Midwest and West draining into the Mississippi and then coming right out in Louisiana and then flowing right over here.

Hal Needham: It's just amazing how everything's interconnected. Some farmer in North Dakota is shoveling and some of that soil goes into the river and that finds its way in the Mississippi, that finds its way in the Gulf and eventually could find its way over to Galveston Island. It's just unbelievable. What's happening 1,500 miles away can affect us here on the island.

J.R. Shaw: Well, it's amazing that we have this historic city that is attached to the beach. So you know, when I think of the beach here in Galveston, I think of it as a plus, not really the draw, because it is such a historic place, you know.

Hal Needham: The deadliest disaster in US history and rebuilding the island, the grade raising. We have all this inspirational history here. So it puzzles me when people's perspective of Galveston is I visited three years ago on a Tuesday in June and I didn't like the water color. Also, there's a surprising number of blue water days, especially in the summer and early fall. There are a couple of reasons: the winds tend to be lighter at times, and also, there's this south wind that can develop in the late summer or early fall. That brings up saltier water from South Texas, and that tends to have less sediment in it, and it actually can block the sediment coming over our way from Louisiana.

So we tend to get a few more blue water days getting into the later summer and early fall. People will say that it has to have a filter on it. There's no way it's that blue. But we even see in the heart of tourist season, May, June, and July, you get three days in a row with light winds, and all of a sudden, people are saying, is that the real water color? Is that photoshopped? It's like, no, it really looks that way. So people often are surprised. We do. We do get quite a few clear water days as well.

J.R. Shaw: Well, Hal, thank you so much for coming in today. I really appreciate you stopping by and telling us about Galveston's water color. Yeah, thank you so much for having me on the podcast. Yeah, for sure.