On the cold and foggy morning of Saturday, December 13th, interns from Pittsburg High School and Antioch High School came together for an event at Big Break Regional Shoreline. Located in Oakley, CA, Big Break sits along the inland coast near the point where the San Joaquin River and Sacramento River meet, creating what’s known as an inverted delta. This means that multiple inland river channels narrow towards the end of the delta, enter the Bay, and eventually flow out into the Pacific Ocean, rather than the typical structure of one river fanning out into a delta at the mouth of an ocean. While this specific geographic feature is a foundational to the ecology of the Bay Area, it is uncommon around the rest of the world.
East Bay Regional Park District (EBRPD) staff members working at Big Break have done an amazing job taking advantage of this unique environment for educational purposes, running weekly Delta Discovery activities and events for the public, and partnering with Earth Team to give our interns a tour of this critical estuarine habitat. Starting in the visitor center, EBRPD Naturalist Aki introduced our group of over 20 interns to the wonders of Big Break.
The interns explored a variety of thoughtful, fun, and hands-on exhibits, like using a microscope to view organisms up close and tracing pictures of coastal birds to identify different migratory species. They even had the chance to observe staff feeding native fish in an exhibit tank as well as a turtle who is named “Gus” after the asparagus which used to be farmed there.
After hearing more about the history of Big Break, the interns followed Aki outside, walking along the paved road until reaching the Levee Top Trailhead. Aki led the group along this trail, making his first stop at a couple of owl and bat houses. Here, he explained that it is important to help establish populations of these species not only to maintain a robust and diverse habitat, but also to control pest species in a balanced ecosystem. For example, the interns learned how the simple need for food leads bats to help control mosquito populations and owls to manage mice in the area. They even witnessed a barn owl take flight from one of the birdhouses soon after.
Aki continued the walk, approaching a series of distinct, slick tracks left on muddy slopes by river otters sliding down from the trail into the waterways on their bellies. Around these otter slides, interns were encouraged to observe the scat found on the ground. They worked together to evaluate the color and texture of the scat, proposing what might be included in river otter diets, such as crayfish.
Aki also informed the interns of other native species present at Big Break, teaching them how to identify plants along the trail, including blackberry bushes and coast live oak trees. He similarly identified rosehips, which the interns had the chance to taste right from the bush. Aki explained how the indigenous peoples of this land, primarily the Ohlone tribe now known as the Bay Miwok, were the original environmental stewards of the region, relying on the native acorns and berries as a food source. The interns also learned how the Bay Miwok used tule reeds to build boats that allowed them to explore the rest of the delta and remain connected with other Ohlone tribes.
Throughout the rest of the trail walk, interns were given many opportunities to ask questions, leading to a discussion of the importance of wetland ecosystems in maintaining productive carbon sinks. Aki reinforced their understanding of how the restoration and protection of highly productive wetland environments helps promote nature-based solutions for carbon sequestration; ultimately, working to mitigate climate change.
Upon finishing the trail walk and returning to the paved pathway, the interns followed Aki to an outdoor 3D topographic map built into the ground of the Big Break picnic area. Known as the “Delta Discovery Experience,” this interpretive landscape depicts the Delta watershed all the way from Sacramento to Suisun Bay, covering a 1,200-square-foot scale. Interns were given watering cans that they then poured into different areas of the map to emulate the flow of precipitation through the watershed and out into the bay. This watershed exercise was provided by EBRPD staff who joined Aki in sharing the importance of protecting the delta.
The tour of Big Break ended at the pier looking out across the delta. Here, interns spotted a blue heron and some cormorants as they listened to Aki share about the coastal and shorebirds that need Big Break, as well as other areas of the delta, as critical habitats in their migratory paths.
Upon finishing the walk, most interns returned to the visitor center to shelter from the cold weather and explore more exhibits, while a small group completed an OVTA litter assessment of the adjacent parking lot. To their pleasant surprise the site is so well maintained that there was hardly any litter to clean up. This was an encouraging end to an enjoyable event. Thank you so much to our partners at East Bay Regional Parks District who made this experience possible for the interns, as well as support from the Whale Tail Grants Program funded by the California Coastal Commission.
