Welcome to Santa Cruz
Tucked beside the beach and the bustling streets of Santa Cruz, this small garden does more than just look pretty. It's actually part of a smart, nature-based system designed to protect Monterey Bay. Known as a bioretention garden, this landscape feature uses soil, stone, and plants to absorb rainwater and filter out pollution before it can harm the environment. This EarthCache will guide you through how stormwater moves through urban spaces, why it can become polluted, and how simple solutions like this garden help clean and slow that water down. Along the way, you'll uncover key lessons in hydrology, soil science, and environmental stewardship.
The Geoscience Behind Bioretention Gardens
When it rains, water naturally wants to soak into the ground, but in paved environments like parking lots and roads, it has nowhere to go. Instead, it flows over the surface, gathering oil, metal dust, trash, and other pollutants. This untreated runoff usually enters storm drains, which often empty directly into nearby streams and oceans. That’s where bioretention comes in. These gardens are designed with layered soil, mulch, gravel, and carefully selected plants to treat runoff in a way that mimics nature. Here's how the science works:
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Infiltration: Water slows down as it enters the garden, then soaks into the soil rather than running off. The soil acts like a sponge, just like in a natural setting.
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Filtration: As water passes through the different layers, pollutants get caught or absorbed. Sand and mulch trap particles, while clay and organic matter bind heavy metals.
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Biological Treatment: Microbes in the soil break down oil and chemicals, and plant roots absorb nutrients like nitrogen and phosphorus that would otherwise fuel algae blooms downstream.
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Slow Release: Any water that’s not taken up by plants or evaporated can flow slowly through an underdrain into local streams, cleaner and at a much gentler rate.
This Santa Cruz garden is a working model of how geology and biology can be applied in cities to support environmental health. It protects creeks, slows erosion, and keeps toxic runoff out of Monterey Bay.
Why Was This Spot Chosen?
This location was chosen because of its proximity to Monterey Bay and its exposure to heavy urban runoff from nearby roads and parking areas. When rain falls here, it picks up pollutants from the pavement and sidewalks. Without intervention, that polluted stormwater would flow directly into storm drains and then into the ocean.
Monterey Bay is an ecologically sensitive and protected area. It supports marine life like sea otters, kelp forests, and whales. Pollutants from inland areas can cause serious harm here, including algae blooms, fish die-offs, and water quality issues. By installing this bioretention garden, Santa Cruz is taking action to prevent that damage. The design slows water down, filters it, and returns it to the environment in a safer, more natural way. It’s an example of how land use decisions rooted in earth science can help heal and protect critical natural resources.
Tasks for This EarthCache
To log this EarthCache, visit the location and complete the following tasks. Send your answers via Geocaching or email.
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Include “Bioretention Garden - Santa Cruz - GCB9E9A” as the first line of your message.
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Where does the stormwater enter the garden? Describe the slope, swale, or curb cuts that guide water into the garden.
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Look at the surface materials within the garden. What do you notice about the texture and composition of the topsoil or mulch? Why might this be useful for filtering water?
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What types of plants are growing in the garden? Are they native, deep-rooted, low to the ground, or something else? Why might these plants have been selected?
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Why is it important to clean stormwater before it reaches Monterey Bay? Describe at least two environmental problems this garden helps reduce.
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In your log, attach a photo of yourself or a personal item with the Bioretention Gardens sign in the background. (Note: photos predating the publication of this EarthCache are not accepted.)