Arundo donax, a native plant of the Mediterranean region, is a scourge to streams all over California, including the San Luis Obispo area. This plant is a perennial grass which grows in giant stands up to thirty feet tall and often forms large colonies in coastal drainage areas. Because this bamboo-like plant has no natural predators here, it grows unabated and can overtake and replace the native vegetation that local fish and wildlife depend on for survival. Arundo grows very quickly, and in some studies, grew upwards of 6 inches a day. It is a voracious water consumer, making it a threat to some streams that have barely enough water to support fish. Arundo also contains volatile oils that make it a fire hazard. With its multitude of negative effects, this invasive plant is bad news for local creeks – including San Luis Obispo Creek.

San Luis Obispo Creek flows for 18 miles from the base of Cuesta Grade out to the ocean at Avila Bay. In 2002, the Land Conservancy produced the San Luis Obispo Creek Watershed Invasive Plant Management Plan in order to prioritize the worst cases of Arundo and designate treatment for weed management within the 95-square mile watershed. Arundo is a very persistent plant that spreads quickly from cane and root fragments, making it difficult to remove. In order to prevent this spreading, the eradication effort has to target upstream plants in order to reduce downstream spreading, and all parts of the removed plants must be specially handled. After gaining permission from private landowners to remove Arundo from their property, the treated sites are monitored to insure the plant is dead and to re-treat if necessary. Fortunately, the landowners along the creek understand the various problems this plant can cause and worked cooperatively with us to get the work done.

After a decade of persistence, our crews have successfully treated all the Arundo plants in the affected areas of San Luis Obispo Creek Watershed. Although reassessment and retreatment may take up to five years, San Luis Obispo Creek is one giant leap closer to being Arundo-free. When completed, this will make San Luis Obispo Creek and its watershed the first California watershed to eradicate Arundo. Nonetheless, we need to continue annual monitoring and engage private landowners to make sure we don’t get a re-infestation.

If unmanaged, the introduction of invasive species to an aquatic ecosystem affects not only the water but the surrounding land areas as well. Without a plentiful water resource, native plant and animal life cannot survive. In turn, these ecosystems become unproductive, no longer providing the flora and fauna that help maintain our environment. In order to protect and preserve the creeks of San Luis Obispo, we must work together to remove and contain local invasive plant infestations.

Project Partners

  • Department of Fish and Game
  • Avila Beach Trustee Council

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