7T The Watershed Connection What is a Watershed? A watershed is all the land connected by the fresh water flowing through it. Everybody lives in a watershed and everything we do takes place in a watershed. In Sacramento we live in the Sacramento River Watershed, the largest watershed in California. Northern California storms produce precipitation either in the form of rain or snow. The rain runs off the land in the Sacramento River Watershed. This is called runoff. The earth’s gravity pulls all runoff downhill into a branching network of streams or tributaries. Streams come in all sizes from small creeks to big rushing rivers. Each stream connects to a larger one until it reaches the biggest stream in the watershed. The Sacramento River is the biggest stream in the Sacramento River Watershed. It carries the runoff from the entire watershed toward the Pacific Ocean. Less than one percent of the earth’s water is freshwater; the rest is saltwater, ice caps, or glaciers. Only a small portion of the freshwater is available for use by people. Streams provide freshwater for many people in California. We could not survive without them or the clean, fresh water they collect from our watershed. When we take care to keep our streams clean and healthy, we are actually taking care of ourselves and every other living thing in the watershed. Clean water supports many more species (forms of life) than polluted water. In a watershed, everyone is someone’s downstream neighbor. People upstream of Sacramento send us their used water. Then we turn around and send our used water to people living downstream of us. Since we all share the same water, it’s everyone’s job to keep it clean. The quality of water depends on us. 8T The Watershed Connection Sacramento Area Rivers Map 12T Introduction to Vernal Pools What are Vernal Pools? California vernal pools are a rare type of wetland that exists in very few places on Earth. Around Sacramento, the pools are found in rolling grassland. What makes vernal pools different from other wetlands, ponds or lakes is that they are temporary pools. They are totally dry for eight months of the year during our dry season. In fact in order to have vernal pools, you need a wet season and a dry season, just like the Mediterranean climate of California. Dry mud with animal tracks and dove weed in a vernal pool. In Sacramento most rain falls in the winter between December and March. This is when the vernal pools fill with water. Once the rain stops in the spring, the pools begin to evaporate. By the end of April, the pools fill with tiny flowers growing from the once muddy bottom. Vernal pools are so colorful in spring, they are named for spring: Vernal means “spring” in Latin. Within a few weeks all of the flowers have made their seeds and the plants have dried up. By July all that remains of the vernal pools is dried, cracked soil and a carpet of short, brown plants. The pools rest like this for another six months until the winter rains return. Then the cycle begins again. Winter Spring Summer/Fall Wet Phase Flower Phase Dry Phase 13T Introduction to Vernal Pools The Vernal Pool Grassland When rain falls on a vernal pool grassland, some water sinks into the ground and the rest flows slowly over the land as runoff. This runoff flows to streams or into depressions (low places) in the grassland. The water cannot move deeper into the ground in a vernal pool grassland because hard- pan blocks its path. Hardpan is a layer of clay or minerals that water cannot pass through easily. The hardpan can be a few inches to a few feet below the ground surface. Under the grassland, the hardpan acts like the bottom of a bathtub holding up the water. As winter rains continue, rain and runoff saturate (fill with water) the soil above the hardpan. The water perches (sits) on the hardpan. In the upland (the higher, drier areas of vernal pool grasslands) we cannot see this water because the water table is below the soil surface. The only place we can see the perched water is in the depressions we call vernal pools. The only way for vernal pools to empty is by very slow movement of water through the ground or by evaporation. This can take days, weeks or months depending on the amount of rainfall, the air temperature and the size of the pool. While some vernal pools are bigger than a playground, many are no larger than a classroom. No two pools are exactly alike. Throughout the uplands are scattered large humps of soil called mima mounds. Nobody knows exactly how mima mounds and vernal pools formed because it happened long ago. It is likely that earthquakes, volcanoes and floods all helped shape the present land surface over the last half a million (500,000) years. Since human beings did not arrive in California until about 12,000 years ago, vernal pools have been a part of our landscape far longer than people. View of mima mounds and vernal pools from a small airplane. 14T Introduction to Vernal Pools Vernal Pools and Human History For many thousands of years tribes of native people came to the vernal pool grasslands to collect food. As recently as 1868, conservationist John Muir described his first view of spring in the Cen- tral Valley vernal pool grassland. —Sauntering in any direction my feet would brush about a hundred flowers with every step, as if I were wading in liquid gold.— He carefully noted that this natural flower garden was nearly 400 miles long and 30 miles wide. Within 125 years of his visit, up to 90 percent of California’s vernal pools were gone. Most had been drained and plowed to feed the ever-growing population of California and the nation. In the furrows left by the plow, farmers still find the stone mortars and pestles of the native people who had used the land before them. Most of the vernal pools we find today occur in the few large cattle ranches that remain in California. As these ranches are converted to vineyards and new communi- ties, more vernal pools disappear. Military bases are the other refuge for vernal pool grasslands. Much of the land within their fences was not developed during the 1900s. As these bases are converted to non-military uses, roads and buildings threaten these vernal pools too. Looking into a vernal pool is like looking back in time. These temporary wetlands look much like they did over 100,000 years ago. Visiting a vernal pool is like walking into a time when animals roamed this land and there were no people. You can see a piece of what John Muir described and explore a unique part of California’s Stone mortar used by native people to grind seeds and perhaps even fairy shrimp. natural heritage. When you are done, perhaps you can answer a question many people ask, “What good are vernal pools, anyway?” 18T The Three Phases of the Vernal Pool Ecosystem The Wet Phase: Winter in the Vernal Pools As soon as the winter rains begin to puddle in the vernal pools, tiny creatures called bacteria and protozoa spring to life. Many of them feed on detritus, bits of dead plants and animals that lie on the bottom of the pool. These detritus feeders are, in turn, eaten by many other tiny animals. Micro- scopic (very tiny) green plants called algae are the next to appear. They are like tiny floating food factories, providing the energy that powers most of the other species in a vernal pool. Now that the winter pools are full of water and are teeming with bacteria, algae and protozoa, many more aquatic species begin to appear. The water signals to the resting spores, eggs, and cysts of aquatic life that it is time to hatch and grow. Within a few weeks, dozens of species of inverte- brates (small animals without backbones) will be living in the pools. Each aquatic species must hurry and complete its life cycle before the pool dries out in the spring. When vernal pools are full of aquatic life, it’s like putting a meal on the table. Frogs, snakes, birds, and mammals come to the vernal pools for dinner. The food web connects all the species in the vernal pool grassland ecosystem. An ecosystem is a community of plants and animals that depend on one another and their environment for survival. Fact of Life: Not every individual of a species will survive long enough to reproduce. Most will become food for another creature. In an ecosystem the survival of the individual does not matter. The survival of the species is what is important. As long as some individuals repro- duce, the species will continue. We know very little about this ecosystem and the species that call it home. There is so much left to discover. However, we do know one thing for sure: vernal pool creatures need clean water. Clean water is Pacific Chorus Frog the key to abundant life. This baby Water Flea is surrounded by microscopic An aquatic beetle larva known as a “Water Tiger” eats a diatoms. Protozoa, bacteria, diatoms, and algae are all Water Boatman. Like many invertebrates, they are microscopic, meaning we need a microscope to see them macroscopic. Although you can see them with your naked at all. eye, you need a magnifying lens to see their parts.