Simple fencing prevents cattle from entering the riparian zone, identifiable by the line of thick vegetation growing on the banks of the creek.
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Riparian Fencing
from the Morro Bay National Estuary Program
Streams and rivers support a unique and important community of plants that grow along their banks, and those plants in turn provide food and shelter for many animals. This narrow corridor of habitat is called the riparian zone, from the Latin ripa for river bank. Riparian vegetation depends on the water of the stream to sustain it, but it also helps protect the stream in several ways. The shade it provides cools the water. Roots hold banks together during floods. Dense vegetation filters storm runoff, and plant material that falls into the stream serves as critical food and nutrients for the inhabitants of that stream. When riparian zones are degraded or removed, important habitat is lost and water quality is likely to get worse, eventually negatively impacting the estuary.
The Chorro Valley, which runs along Highway 1, drains the northern two-thirds of the Morro Bay Estuary watershed through a series of creeks. Cattle ranching is the single largest land use in this valley, and in many areas cattle have had full access to creek channels and the riparian corridor for a primary source of water and shade. This practice can degrade the riparian zone as the heavy animal’s footsteps and grazing impact vegetation and encourage erosion. The cattle’s fecal deposits also degrade water quality, contributing excess nutrients and potentially harmful bacteria to the creeks.
Estuary Program volunteers regularly collect and analyze water samples in the Morro Bay Watershed for bacteria and other water quality parameters. This sampling has shown that many Chorro Valley creeks regularly exceed the bacteria levels state and federal agencies consider safe for recreational contact, like swimming or wading.
In response to this disturbing monitoring data, the Estuary Program began the Riparian Fencing Project in 2005. The goals of this project were to work with landowners to reduce the impact of cattle on water quality and the riparian zone, without negatively impacting ranch viability. This is achieved by fencing the riparian zone and providing alternate sources of water outside of the creek channel for the cattle. Removing the cattle from the riparian zone eliminates direct fecal contamination, allows the tree canopy and other riparian vegetation to grow, enhances streamside habitat and provides a buffer of vegetation to filter runoff from adjacent pastures before it enters the creeks.
Since the inception of the program, over 75,000 feet, or 15 miles, of streamside fencing has been constructed in the Chorro Valley watershed on seven different creeks. To evaluate the success of the projects, the Estuary Program is continuing our water quality monitoring as well as tracking changes in riparian vegetation over time. These data are analyzed to look for improvements after fencing goes in..
Funding for the Riparian Fencing Program comes from a variety of sources. The California Department of Corrections and Rehabilitation has provided the majority of the funds. The Coastal San Luis Resource Conservation District has been a key partner, helping design and fund the water system components on a number of the projects, and the California Conservation Corps have helped construct fencing on a number of projects. Federal US EPA grant funds support the Estuary Program’s staff time on the project, and the public and private landowners that participate are asked to provide a portion of the cost and to maintain the fences for ten years.
Fencing projects have been completed in portions of most of the upper watershed creeks, including the upper Chorro Tributary of Chorro Creek, San Bernardo Creek, San Luisito Creek, Walters Creek, Pennington Creek, San Benito Creek and Bull Creek. (See map.)
More information on this and other estuary related topics can be found at the Morro Bay National Estuary Program website.
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