What is an estuary? Where do they occur? How do they work? Who lives there? And why are estuaries important to our planet? This collection will answer all of these questions and more. Estuaries are places where fresh water from rivers moving downstream from the mountains mixes with salty water moving upstream from the ocean. Estuaries thus contain both fresh and salty water habitats (places) where many kinds of plants and animals can live and grow. San Francisco Estuary is the largest estuary on the West Coast of the United States and is home to millions of people, plants and animals. Our scientists have been studying all aspects of the San Francisco Estuary for nearly 50 years and we have 35 stories to tell about the people, plants, and animals in the estuary. We will tell you horror stories of how tiny poisonous plants and vampire fish kill other fish, and we have success stories of how conservation saves the lives of tiny mice in marshes and birds along the Pacific Flyway. The Collection of stories is divided into six sections, so you can easily find the stories that interest you the most. The first section describes the many kinds of habitats in the estuary, including rivers, shallow bays, wetlands, and marshes, and what makes them a good home for plants, animals, and people. In the second section, the water quality scientists will describe how they use boats, special instruments, and new technology to determine whether the water is healthy for people, plants, and animals. In the third and fourth sections we will tell stories about how plants and animals live in the estuary. Microbiologists will describe the tiny, microscopic plants and animals that live in the estuary, what makes them grow, how important they are as food for animals and why they are sometimes poisonous. Fish scientists will describe the many kinds of fish in the estuary and how we measure their growth, determine where they are, what they eat, and the ways they use both fresh and saltwater habitats to grow and raise their young. In the fifth section, scientists will discuss how invasions of plants and animals from outside of the estuary have changed habitats and the survival of native plants and animals. Lastly, in the sixth section, we will share how scientists in the estuary are using new technologies and management actions to control invasions of unwanted plants and animals, increase the growth of native plants and animals, improve water quality and restore habitats in the estuary.