Assess students' ability to analyze the causes (point and nonpoint nutrient sources such as agricultural runoff, sewage, and atmospheric deposition), biological and chemical processes (nutrient cycling, algal/phytoplankton blooms, decomposition, stratification, and oxygen depletion), and ecological impacts (biodiversity loss, food‑web shifts, harmful algal blooms, and fish kills) in freshwater lakes; include interpretation of simple data (nutrient vs. dissolved oxygen trends) and evaluation of mitigation strategies.