Fumigation for pocket gophers is of limited use because:

• A. It is expensive
• B. Groundwater contamination will always result after the gophers are poisoned
• C. It is illegal
• D. It kills non-targets too slowly

Answer: (B)

The main idea here is that environmental safety concerns, especially the risk to groundwater, limit how useful fumigation is for pocket gophers. The gases used in fumigation move through the soil with the gopher burrow system, and in soils that are porous or with a shallow water table, they can reach and contaminate groundwater. That potential for groundwater contamination makes fumigation a constrained option, often not practical or permitted in many situations. So, even though fumigation can control gophers, the environmental risk is a major factor that reduces its usefulness.