Use of Sloped Areas in Monterey County

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A watershed-related issue examined by the ENVS 560/L Watershed Systems class at CSUMB.


The current update for the Monterey County land use plan is being reviewed and open for comment until February 2, 2009[1]. One issue is the use of sloped areas in the county, which are currently restricted, but not always explicitly. Lands with steeper slopes are heavily impacted by erosion when the soil is disturbed by any practice. The updated plan calls for a permit process that would be required of any conversion of slopes greater than 25% to agricultural land uses. Development of such lands for residences or commercial uses will continue to be prohibited or restricted, depending on the subarea of the county. The pending permit process has had the effect of pressuring property owners to begin tilling marginal high-slope lands so that use will be "grandfathered in", bypassing the permit process[2].


Monterey County is on the central coast of California, the Mediterranean climate supports ecosystems on sloped areas ranging from chaparral and coastal scrub, to grazing lands dominated by introduced annual grasses, to Monterey Pine forests. Oak woodlands, and riparian areas[3].

Resouces at Stake

Vegetated slopes provide grazing lands for livestock and habitat for a variety of species. Sloped areas are usable for vineyards, though with decreasing yield and return on steeper slopes. Disturbance of the soil leads to increased sediment load in streams and rivers and a loss of topsoil, topsoil which is economically unfeasible to replace. Increased runoff can add to the flood potential of streams and rivers in the watershed.


Though there are environmental groups such as the Sierra Club [1], The Nature Conservancy [2], and local groups concerned about ecological issues, property owners are the biggest stakeholders monetarily. Actions against violating property owners are often initiated by neighbors impacted by wind and water erosion, increased runoff, and/or the visual impact of changes in sloped areas. The Monterey County Water Resources Agency [3]and the Regional Water Board oversee policies and practices for watersheds in Monterey County.

Laws, Policies, and Regulations

The use of sloped areas is addressed by several regulatory bodies, the Monterey County General plan addresses the use of sloped areas in the following ordinances: General Plan, 4.4.3 and 16.12. Specific area codes addressing slope include S 1.1, 1.2, 1.5, 1.6 and 1.8, NC 1.3, T 3.6, and Cach 3.2. Open space codes include O.S.1.3-1.6, 3.4, and 3.6, and agricultural regulations are found in Ag5.1 and 5.4. The above list is not comprehensive and includes uses other than agricultural. Most regulations require either a permit process or site mitigation for agricultural (pending approval) or other uses on slopes greater than 25%.


Factors affecting the amount of erosion include percent slope, amount and type of organic matter in the soil, soil type, rainfall, wildfire severity, and other local factors. Disturbed lands will support regrowth of vegetation, but rains or irrigation will likely remove some topsoil before plants are established, and topsoil loss will increase even with establishment of vegetation. Disking and other mechanical activities cause some downhill movement of soil by the simple movement of equipment, and the percolation of water, enhanced by following the roots into lower strata, is greatly diminished once the upper strata are disturbed. Areas left bare, such as those underneath vines, remain highly erosive. In the absence of percipitation, which is the majority of the year on the Central Coast of California, wind erosion also removes soil from disturbed areas.



  • Carefully placed sediment traps, with overflow socks to trap the finer particles, are useful for collecting data on the amount of sediment being carried away by erosion by water, but are obviously useless for measuring wind erosion. Data can be analyzed, modeled, and compared to similar studies on similar or differing soil types and slopes.
  • High resolution Airborne LIDAR may be a great way to study soil erosion over time as well as any changes in slope from land use.

Future Research

A local study of soil and wind erosion comparing undisturbed habitats, grazing land, vineyards, and dryland or irrigated farming on sloped areas with typical soils would be a useful document and a guide for future policies and practices in Monterey County.


  1. Need link
  2. Need source
  3. Need source


This page contains student work completed as part of assigned coursework and is not comprehensive in scope. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.