Step-by-step explanation:
Positively:
Runoff pollution can be limited by people in many ways.
If farmers and gardeners reduce the amount of fertilizes they use,
If urban areas reduce the impervious surface as soil is a natural sponge which can absorb many harmful chemicals.
Negatively:
The population increases day by day and more urbanization occurs therefore, more of the natural land is replaced by impervious surface such as roads, buildings, park, shopping malls, parking lots etc. As it covers the soil so the absorption of chemicals and filtration reduces due to which streams and ditches form.