ROMA, Texas (Border Report) — As the South Texas sun recently peeked over the horizon and glistened on the Rio Grande, something else became visible: Several tiny islands that have formed in the middle of the river.

The mini islands have formed off the riverbanks in rural Starr County in deep South Texas, and have become a hiding place for drug smugglers and human traffickers, and even spots from where U.S. agents have been fired upon.

They are the product of sediment that has built up over time and with the tide flow, forming land masses right in the middle of this international river the United States shares with Mexico.

They are in effect “no-man’s land” — literally in between the border. And they have become a popular hiding ground for those trying to illegally enter the United States across the river, or trying to bring in narcotics, U.S. Border Patrol agents say.

Christian Alvarez, a Border Patrol supervisory agent stationed in the Rio Grande Valley Sector, said the wild brush and vegetation on these landmasses — some estimated to be about 50-feet wide — allow those with nefarious intentions to get half-way across the river, lay low and then wait for U.S. agents to leave an area at which time they can high-tail it across the remaining 40-yards of river to the U.S. side.

Sometimes, in the summers when the water levels are low-enough, “you can even see them walking across,” Alvarez said on Thursday as he took Border Report on a four-hour tour of this region.

There are at least two islands that have formed near Roma in the middle of the river, and one near the town of Escobares and another near the tiny town of Fronton, near where a new border wall currently is being built. (Read a Border Report story on the new border wall at the Arroyo Ramirez National Wildlife Refuge.)

They are unnamed and virtually untamed lands.

Agents said they do not cross the river to patrol the islands, and they said they have asked the International Boundary and Water Commission (IBWC) to whom these lands belong.

Border Report also asked IBWC’s U.S. Sector for clarification on these landmasses. A spokeswoman said they are called “islands” because they are free-standing and surrounded by water on all sides, and that they were formed by sediment. They also are problematic because birds and wildlife nest and live in them, creating environmental concerns.

“The islands are formed, which are sediment and sand bar accumulations and islands is the correct term,” IBWC spokeswoman Lori Kuczmanski said Monday.

As to the question of sovereignty, the anticipation of these future islands popping up was included in the 1970 international water treaty with Mexico.

The treaty between the U.S and Mexico specifically addresses the “uncertainty” to which country these islands belong and states the international boundary line is the “middle” of the river channel, except where these islands occur. Then, the demarcation line is figured by the following scientific formula stated in the treaty: “Where either of the rivers has two or more channels, along the middle of the channel which in normal flows has the greater or greatest average width over its length, and from that time forward this international boundary shall determine the sovereignty over the lands on one side or the other of it, regardless of the previous sovereignty over these lands.”

The U.S. Section of the IBWC, which is based in El Paso, maintains updated maps showing each island and its sovereignty, Kuczmanski said.

This image from Google Earth shows a river island in the middle of the Rio Grande in an area of the border between Roma and Escobares, Texas.

A few years ago, a woman and a man who were jet skiing on the Rio Grande in Starr County near Roma were shot from one of these islands, and in August 2019, a U.S. Border Patrol marine unit came under heavy fire from an island near Fronton, Alvarez said.

“Smugglers will use it as a staging area because of the thick brush where they’ll either stash up narcotics or hold their people there, the aliens that they’re going to cross and just wait for an opening. It’s an advantage for them because they only have to worry about crossing half of the river at that point. They can wait us out as long as it takes until everybody sees that it’s clear,” Alvarez said.

It’s an advantage for them because they only have to worry about crossing half of the river at that point. They can wait us out as long as it takes.”

Christian Alvarez, Supervisory U.S. Border Patrol Agent

Although a Border Patrol news release about the Fronton marine shooting event said agents “were shot at from the Mexican riverbank,” it’s unclear whether or not that actually is Mexican territory. The Border Patrol marine unit was hit by 50 rounds from automatic weapons, and agents said the boat was so badly shot up that it was brought to the Rio Grande Valley Sector’s headquarters in Edinburg, about 65 miles away, where it sat on display to warn agents of the dangers of this part of the river.

None of the agents on board were hurt, however, and no arrests were made. The news release said agents at the time had seen four men on the shoreline, but with the swift international waters as a safe zone that U.S. agents will not cross, they were never found.

To help patrol these unmanned waters, mobile surveillance cameras are set up on the U.S. side, especially near bends in the river, facing the islands, agents said.

But to evade agents, smugglers and human traffickers will overfill plastic rafts and float from the islands to the U.S. shoreline where they will grab onto hardy and invasive carrizo cane and hold on to it and duck and hide in the reeds until they have clear spot to exit and run onto U.S. soil.

“Once they come across they’ll tell them get on a trail and go straight up the road,” said U.S. Border Patrol Agent Brian Martinez, who is assigned to the Rio Grande City Station.

Well-worn foot trails are visible on the Roma Bluffs, a famous bird-watching area where agents say smugglers and traffickers trek daily after disembarking on the river bank.

The Rio Grande City Station “is the busiest in the nation for interception of marijuana and drugs,” Martinez said.

“A lot of times these smugglers will get these rafts, they probably shouldn’t hold more than 2-3 bodies and a lot of times they come over not only with people inside the rafts but with people hanging onto the sides of it. One smuggler is swimming everybody across,” he said.

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