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The Arroyo Seco Foundation are Stewards of the Arroyo Seco. We are leaders in the environmental stewardship of the Arroyo Seco watershed, and we advocate for its protection and preservation.
Our citizen scientists work to preserve the region’s ecosystem and watershed by surveying the population of native rainbow trout, by protecting and restoring the riparian habitat, by participating in habitat restoration efforts, and by monitoring water quality within the Arroyo Seco.
Our data is shared with local and state agencies, to assist with education, planning, and management of this priceless environmental treasure.


Features of the Arroyo Seco Watershed:
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The watershed begins in the Angeles National Forest near Mount Wilson in the San Gabriel Mountains
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The watershed comprises about 47 square miles
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The stream is approximately 24 miles long
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Water from the stream helps to replenish the Raymond Basin, an aquifer underlying Pasadena that provides about one third of the local water supply
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The stream passes underneath the Foothill Freeway and was engineered into a concrete flood control channel
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The concrete channel has impacted water flow and quality
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The stream flows south into the LA River and discharges into the ocean at Long Beach
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Trout no longer inhabit the lower part of the stream, and there are numerous barriers to fish migration to/from the ocean


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