To download the most current version that Louisiana DEQ has posted on their website (Version 11.0 as of October 2023), click here and scroll down to the LA-QUAL model link under the heading TMDL Water Quality Modeling. No login is necessary to download this model from the Louisiana DEQ website. An older version of LA-QUAL (Version 9.38) is also available on the Louisiana DEQ website here.
The LA-QUAL model defaults to the Louisiana DEQ defaults. However, for any given version number, the LA-QUAL model will yield identical results to the QUAL-TX model used by the Texas Commision on Environmental Quality (TCEQ) if the the "Model Assumptions" are set to "Texas (TCEQ) defaults" in the menu Preferences/Additional Preferences. LA-QUAL may have newer versions than QUAL-TX with additional enhancements and corrections not available with QUAL-TX. These will be shown in the version history above.
Download zipped file with LA-QUAL executable, User's Manual, and example data set (these downloads require login):