Sometimes rivers can be close to each other but be very different. Consider, for example, North Branch River and South Branch River. The North Branch River is very clear. The sand on the bottom is so clean it sparkles like stars in the sky. Sometimes you can see fish swimming in the water. Trees and grass line the banks of the North Branch River. The South Branch River is very different. The South Branch River has many towns along its banks. There is a paper mill in one town. Another town has a mine that dumps waste into the river. Sometimes even the air near the river smells bad. The South Branch River has mud on the bottom. No fish swim in the polluted water. Soon the South Branch River will be a dead river.