The author describes the unexpected benefits of modifying culverts in Section 2.
In paragraph 2, the author begins to discuss the unexpected benefits of modifying culverts by mentioning how it can help improve fish populations. In paragraph 10, the author explains how modifying culverts can also benefit other wildlife species like turtles and salamanders. And in paragraph 13, the author describes how modifying culverts can reduce flooding and erosion, providing additional benefits.
The author describes the unexpected benefits of modifying culverts in Section 2 of the passage. In this section, the author explains how modifying culverts can improve the health of aquatic ecosystems.