Study the organization of the following passage. Paragraph 1: [1] A water-quality report summarizes a yearlong sampling project. [2] Winter samples established baseline levels before nearby construction began. [3] Spring samples were collected weekly during the first excavation work. [4] Researchers increased sampling after two storms carried visible sediment into the stream. Paragraph 2: [5] They also added a site downstream from the construction entrance. [6] The expanded record helped distinguish ordinary seasonal change from storm-related spikes; the timeline explains why the sampling design changed. The writer wants to add this sentence: "In midsummer, unusually heavy rainfall shifted the project from routine monitoring to event-based sampling." At which location does the sentence form the most precise bridge between neighboring ideas?