ALAMO, Texas - New details are emerging on President Trump's border wall and the possible locations where it could be built, including wildlife centers, private property and federal land. Pre-decisional maps obtained from U.S. Border Patrol outline the possible path the wall could take, pending approval and congressional funding.

Down a dirt levee road near Alamo, Texas, passed a steel gate, and about a mile north of the U.S.-Mexico boundary, lies the Santa Ana Wildlife Refuge. It is a 2,088 acre nature sanctuary for approximately 400 species of birds and plants. It’s also where the local U.S. Border Patrol said they need a wall.

“This particular area is one of the ones that is being suggested to be the first one because of the criminal organizations exploiting the area,” said Border Patrol supervisor Daniel Tirado.

Tirado said Border Patrol officials are working a delicate balance to deliver border security with as little environmental impact possible. That’s why the border levee, which snakes parallel to the Rio Grande River is being considered as a possible location for the wall.

“The vegetation is so dense that vehicles cannot traverse through it along the river,” said Tirado. “There’s absolutely no lateral access along the river in these particular areas where that infrastructure would actually get control of those areas.”

Just last Saturday, agents reportedly intercepted a group of smugglers and undocumented immigrants who used the refuge as a staging point.

The proposal has renewed an outcry by environmentalists ever since news broke in July of the government collecting soil samples along the levee near the refuge, fearing the wall could disrupt the habitat.

The Border Patrol said agents have been meeting with local stakeholders to address these issues.

They’ve shared these maps outlining the possible areas the wall could cut through, including populated cities like Roma, Texas and nature centers like Santa Ana in Alamo and the National Butterfly Center in Mission.

These are also areas federal authorities consider smuggling hot spots.

Local environmentalist and president of the local Sierra Club, Scott Nicol, attended one of said meetings, and said he was pleased that Border Patrol official listened to his concerns. However, he was unsure whether his concerns would end up making it all the way to Washington.

“What was unclear was the extent to which those concerns would influence their actions. Decisions about where walls will or will not go and what design will be employed appear to be originating in D.C., not at the sector level,” said Nicol in a written statement.

Border Patrol stresses that plans could change at any moment. It now vows to keep these organizations informed as the process moves forward.

“We’re still in the preliminary stages of conducting all the tests and environmental assessments. All that may possibly change the final product,” said Tirado.

As many as 51 non-profit organizations are staging a rally at the wildlife refuge Saturday in response to this border wall proposal. They are hoping to influence the final decision as to where the wall will ultimately cut through.