Field trip to Tule Ponds and Tyson's Lagoon
Background InformationIt has long been observed that wetland ecosystems provide a natural treatment of water. The San Francisco Bay's water quality has been compromised due to the introduction of pollutants (from farming, waste, and industry), and the destruction of the natural marshes which once bordered the bay. Construction of manmade ponds, lagoons, and marshes is being experimented with, in an effort to clean-up the waters entering the bay. In addition, areas of land that were once marshes bordering the bay are being allowed to return to their natural state.
Tyson's Lagoon formed sometime in the 1890's after an earthquake along the Hayward Fault left a depression . This depression filled with water and became a draining site for the area of upper Mowry Rd, Walnut RD, and some older and newer homes in the Mission area. Presently the drainage also includes some farmland. From Tyson's Lagoon the waters travel under major streets and above ground along the northern side of Mowry Ave. towards the bay. Waters from the Fremont Hub area join with these waters. The water proceeds to the bay until it dumps into the Mowry Slough and enters the south/east end of the San Francisco Bay.
In an effort to clean-up these waters before entering the bay, the Tule Ponds were built in the summer of 1998 on the site of Tyson's Lagoon. These ponds are an experiment. The following description is a theoretical proposal of what is expected to occur in the pond system. The Tule Ponds are a series of three shallow ponds. Storm water should enter pond number one, at the right, back of the site, move into pond number two, pond number three and finally empty into Tyson's Lagoon. The impurities in the water should settle out as the waters move through the ponds. The ponds are designed such that water will be slowed as it moves around islands and other manmade barriers. This slowing of the water will allow impurities to settle out. Metals and pesticides are some of the things that will settle to the bottom of the ponds. Floating log barriers are set up between pond two and three to hold back floating debris and oils that may not settle to the bottom of the pond. From pond number three, the water will drain into Tyson's Lagoon, much cleaner than when the storm water entered the system.
Tyson's Lagoon has long been the home to a variety of wildlife. In an effort to preserve this habitat, much of the area has been left in its natural state. You will notice many shore birds as well as the Canadian Snow Geese that each year make Fremont their winter home. In the spring nesting sites can bee seen. Please caution students to stay away from nesting sites. Indigenous California plants have been replanted in this area to preserve the natural look of the site.
Tyson's Lagoon is home to many tules. Tules were used by the Ohlone
people to make boats that could be used to travel and fish in the San Francisco
Bay. Bundles of tules were lashed together to build canoe-like boats. Tule
reeds are composed of a spongy material that has many air chambers. These
air chambers allow the tules to float. Many tules lashed together can make
a boat that is strong enough to carry several people. Eventually the air
holes fill with water and the boat no longer floats.
Student Activities for Tule Ponds and Tyson's Lagoon:Materials to bring to Tyson's Lagoon:
Copies of the lab sheets and map for each of the students
Plant, bird and microorganism identification booklets - one set for each group of five students
Begin the exploration of the pond site at the entrance overlooking pond three. Each student should have their handouts and their map. You will be looking at the ponds in reverse from pond 3 to pond 1, then proceed to Tyson's Lagoon. Students will be making microscopic and macroscopic observations as they move from pond to pond. Their laboratory sheets will guide their questioning and observations. Use the lab sheets to initiate discussions as you proceed. Conclusions can be made at the end of the field trip, or if time does not allow, in the classroom.
Station 1 - Observation Deck
Explain the layout of the pond site and the path the water takes through the ponds. Note areas where the water enters the system on the map and again as you pass these inlets. Have the students trace out the water pathways on their maps.
As the students move from one station to another have them be aware of the plants and animals in the area. They are required to identify one bird and one plant using the plant and bird identification booklets.
Station 2, 3, and 4 - Pond 3, 2, 1
Students need to describe any signs of pollution they see in this pond. Be sure they include oil and scrum floating on the surface.
Using the water samplers, retrieve a sample of pond water for the students to look at under the microscope. Students will need about two drops of water to fill the wells of their slides. Review how to use the GH microscope with the students before proceeding. Review the laboratory sheet for this station before passing out samples so that the students will be ready to proceed on their own. Ask the students to refer to their microscopic life booklets to try and identify any life they observe.
Stations 5 - Tyson's Lagoon
In addition to those observations done at the other stations, ask the students to look for other signs of life. Shells, bones, and even crayfish are often seem at this site.
Tules grow all around Tyson's Lagoon. Before beginning the microscopic and macroscopic observations explain what a tule is, and why it was so important to the Ohlone Native Americans. (Refer to background information) In addition, pick a tule and toss it into the lagoon. Point out that it floats and that when bundles of them are lashed together they formed a floating boat for the Ohlones. These boats were never designed for the ocean as they are not able to withstand large waves, but were used extensively to traverse the San Francisco Bay, and for fishing the local waters.
Tear a tule open and allow the students to see the air chambers inside. These chambers are the reason the tules can float. Break off a bit of tule for each group to examine under the microscope. Ask them to draw what they see on their lab sheet.
Station 6 - Overlook
Conclusion - This step can be completed in class or while waiting to leave Tule Ponds.
Ask the students to take out their maps of the area. Use this map and
there lab sheets to answer the following questions. You may wish to first
discuss the questions, brainstorm answers and them allow the students time
to answer the questions.