A fish kill along in Mexico this week has state environmental experts concerned for Falcon Lake.
It's believed an unknown material may have leaked from a Pemex oil plant in Mexico and is making it's way down the Rio Salado, which enters the Rio Grande and ultimately dumps into Falcon Dam.
State experts want to know if it has, or will, contaminate Falcon Lake.
The International Boundary and Water Commission and the Texas Commission on Environmental Quality are doing tests on water taken from the lake.
No water contamination has been observed but a precautionary notification is in place because official tests from the lab will take several days.