Is an AMSCLAE opinion mandatory for a building permit at Atitlán and which wastewater rules apply?

The AMSCLAE Regulation (Governmental Agreement 78-2012, article 46; its founding statute is Decree 133-96) states that municipalities, before issuing licenses for new public or private buildings, refurbishments or well drilling,… 'may' request the relevant opinion from AMSCLAE,… to be issued within no more than fifteen working days,… without prejudice to the environmental assessment instruments. The verb is permissive for the municipality, although secondary summaries present it as mandatory. The procedure 'prior opinion for municipal licenses' appears in the state's catalog of procedures with no published requirements, cost or turnaround. For wastewater, AG 12-2011 (discharges in the lake basin) and AG 236-2006 (the national regulation) apply, and for environmental assessment, AG 137-2016 with the exhaustive list AG 199-2016.