What is the purpose of rainfall data in planning and inspecting stormwater BMPs?

• A. To determine plant species.
• B. To adjust soil pH.
• C. To trigger BMP activation, plan sampling during rain events, and assess performance under representative hydrographs.
• D. To estimate project cost.

Answer: (C)

Rainfall data ties precipitation to how stormwater BMPs behave. By looking at rainfall intensity, duration, and total amounts, you can decide when a BMP should activate to control runoff, plan sampling to occur during actual rain events so the data reflect real operating conditions, and interpret results using hydrographs that show how flow and pollutant loads rise and fall over the storm. This approach ensures you’re evaluating performance under representative storm conditions, not just in dry periods. The other options don’t fit because rainfall data isn’t used to pick plant species, adjust soil pH, or estimate project cost in the context of planning and inspecting BMP performance.