If in an area, minor water contamination or nuisance is addressed. In this respect, do local government officers have powers to enter for investigation?
Yes, local government officers have powers in this context.
They are authorised persons under law and may enter for investigation if
(i) the occupier consents to the entry.
(ii) it is a public place and the entry is made when the place is open to the public.
(iii) it is a place where an industry is conducted and the entry is made when the place is open for conduct of business.