pollution

means the direct or indirect alteration of the physical, chemical or biological properties of a water resource so as to make it—

(a)less fit for any beneficial purpose for which it may reasonably be expected to be used; or
(b)harmful or potentially harmful—
(aa)to the welfare, health or safety of human beings;
(bb)to any aquatic or non-aquatic organisms;
(cc)to the resource quality; or
(dd)to property.