President-elect Donald Trump announced Wednesday that he intends to build a border wall as soon as he takes office.

“We are going to build a wall, I could wait about a year and a half until we finish our negotiations with Mexico, which will start immediately after we get to office, but I don’t want to wait,” Trump said.

Hours after Trump’s message, Rio Grande Valley residents gathered at Yerberia Cultura in McAllen to hear about the environmental damages the wall could pose to the region.

The discussion was led by Scott Nicol, the Co-Chair of the Sierra Club’s Borderlands Team, an environmental organization.

Nicol said among the problems that may come from the structure, flooding is a major concern.

“The walls can act like dams, they can channel wall in places, they can divert water into communities, they can block water that would otherwise exit those communities, they could do a tremendous amount of damage both in the united states and in Mexico,” said Nicol.

Based on documents Nicol obtained through the Federal Freedom of Information Act, the government faces few obstacles to building the wall in parts of the valley, including federal land set aside for endangered species.

The evidence presented by Nicol that suggest the environment will be affected by the wall, surprised many of those present at the event.

While many local residents are preparing to fight against the construction of a border wall, Hidalgo County Republican Party Chairman Sergio Sanchez said something must be done to resolve the immigration issue.

“We fully expect him and the rest of the republicans to follow through and do something to withstand this flood of illegal immigration, disincentivize families from calling back home and telling more of their family to come up to South Texas, come up the U.S. illegally,” said Sanchez regarding the way migrants maneuver through the system.