Final answer:
The area where residential construction is prohibited in the survey may be a designated protected zone due to zoning regulations related to the river area.
Step-by-step explanation:
The area where residential construction is prohibited in the survey may be a designated protected zone due to specific zoning regulations related to the river area. Zoning regulations can be put in place to preserve certain features, protect ecosystems, or maintain historical or cultural significance.
These regulations may restrict areas to single-family homes, multi-family dwellings, or townhouses, and may cover various factors like lot area, yard requirements, off-street parking, and number of buildings or dwelling units in an area.