The water quality of Beheshtabad River in Iran was evaluated using a water quality index and statistical methods. Measurements of various factors like nitrate, temperature, and pH were taken at different points along the river. Results showed that water quality ranged from average to good, with pollution increasing from upstream to downstream. Factors like agricultural fertilizers and wastewater discharge were found to be main contributors to decreased water quality. To protect the river from pollution, strict rules and guidelines are needed to ensure the health of the water and preserve it for future generations.