Which of the following statements is NOT true regarding suspended solids?

The statement that suspended solids are always harmful to water quality is not true. While suspended solids can indeed have negative effects on water quality—such as clogging fish gills, reducing light penetration for aquatic plants, and serving as a medium for pollutants—they are not inherently harmful in all situations. For instance, natural events like rain can increase suspended solids from soil erosion, which is a normal part of many ecosystems and can even provide nutrients to aquatic environments.

In contrast, suspended solids are particles that are small enough to be held in suspension in water, which aligns with the understanding presented in the other statements. They can be visible under certain conditions, depending on their concentration and composition. Additionally, suspended solids can originate from both natural sources, like sediments from rivers or lakes, as well as anthropogenic sources, such as industrial discharges or runoff from urban areas. This multifaceted nature of suspended solids highlights that their impact on water quality is context-dependent rather than absolute.