Land Use and Restoration Activities

in the Sonoma Creek Watershed

 

Tom Bakke

American River College

Geography 26, Spring 2000

 

Abstract

Geographic information system (GIS) has become a powerful tool for collecting and analyzing data on environmental impacts.  In the Sonoma Creek Watershed in Sonoma County GIS data is being used to evaluate the various land uses within the watershed, and to select, implement and evaluate various ecological restoration activities.  While this process is ongoing, it has attracted the cooperation and coordination of the important organizations, both public and private.

 

Introduction

There is a growing awareness in the Valley of the Moon in Sonoma County that over-development constitutes a threat to the health of the valley’s watershed and its ecosystem.  This awareness is manifested by the differing opinions over the pace, patterns and practices of vineyard development.  The rapid growth of the wine industry has led to continued conversion of woodlands to vineyards, erosion problems, concerns over the use of water resources, and rapid growth of population and its related issues.

 

This paper has two objectives.  The first objective is to identify the Sonoma Creek Watershed and the various land use patterns that have impacted the watershed.  The second objective will be identify and describe efforts within the past five years to restore the watershed.

 

The Sonoma Creek Watershed is a subpart of the Suisun Marsh and San Francisco Ecological Zone (CALFED, 1998).  The watershed (Figure 1) encompasses most of the Valley of the Moon, beginning in the North near the town of Kenwood and continuing south to the San Pablo Bay, approximately ten miles south of the town of Sonoma.  The watershed is bounded on the west by the Sonoma Mountain Range, and on the East by the Mayacama Range, forming the border with Napa County. 

 

Figure 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Background

The fundamental problem is the deteriorating health of the watershed.  The Sonoma Creek Watershed currently is on the Regional Water Quality Control Board’s Impaired Waterbodies List (SSCRCD, 1997).  Serious sedimentation and erosion problems, and those anticipated by replanting and expansion of vineyards led to the development, in 1993, of a watershed enhancement plan to address these issues.  Many of the activities addressed in the enhancement plan are still in progress.  Concerns about the health of the estuary in southern part of the watershed has also resulted in a plan for federal acquisition of this land for a national wildlife refuge (FWS, 1995).

 

The main impacts on the watershed are increasing urban development and conversion of woodland to vineyards.  The continued rapid growth of vineyards, especially on steep slopes, has caused a public demand for more local governmental control of vineyard practices (Chorneau, 1999; Weiser, 1999).  A recent survey found that 53.4 percent of county residents felt that “too much acreage was planted” in wine grapes, 52.2 percent felt that “more controls should be placed on planting vineyards”, and 44.6 percent “[had] concerns about the impact of vineyards on the environment” (Richard Hertz Consulting, 1999).  In December 1999 a county ordinance was implemented that requires fees and permits for replanting and conversion of land to vineyards (CACCS, 1999).  The ordinance also specifies the required environmental actions to control erosion and sedimentation, and regulates or prohibits planting on steeply sloped land, according to percent of slope.

 

The identification, restoration and maintenance of watersheds as the basis of environmental planning and resource protection (SFEI, 1998) is well understood.  Many activities have been implemented in the past five years to identify the impacts on the Sonoma Creek Watershed and to restore watershed to better health.  The Sonoma Ecology Center, located in the town of Sonoma, has become the lead for coordinating these activities.  The process of indentifying these impacts is being accomplished through its GIS Project.  The goal of the GIS Project is to develop a base model of the Sonoma Valley region that describes the natural features, such as geology, hydrology, topology, plant communities and animal habitats; and human features such as land use and infrastructure.

 

Methods

The primary method for acquiring land use pattern data was to (1) obtain the relevant existing GIS shape files from public or proprietary sources, and (2) develop GIS shape files from printed sources (e.g., maps) and/or aerial photos.  Shape files for the roads within the watershed were acquired from ESRI as a byproduct of purchasing ArcView base software.  Shape files for the Sonoma Creek watershed, rivers and creeks and rehabilitation projects were acquired from the Sonoma Ecology Center through their GIS Project (See www.vom.com/sec and additional sites in references).

 

Some of the shape files obtained from the Sonoma Ecology Center were in North American Datum 1983 (NAD83), while others were in NAD27.  All GIS files were converted to NAD83 to allow projection within the same view.

 

Shape files of the Sonoma Valley appellation regions and the vineyards land use coverage were initially requested in written form from the Sonoma Valley Grape Growers’ Association, at their suggestion.  This request was denied.  Therefore, a detailed poster reproduction of the Sonoma Valley appellation regions (SCGGA, 1999), derived from the GIS files, was purchased.  A sample theme of the vineyard acreage was re-created for this project by using the Sonoma County streets shape file as the active theme, selecting “new theme” from the view menu in ArcView, then using the polygon tool to create the individual vineyards.  The attribute file was subsequently edited to add vineyard owner, identification numbers and acreage.

 

Data for creating other polygon shape files were culled from printed materials as in the manner described above.  Data used for identifying acreage for federal acquisition and protection of wetlands was obtained from The Final Environmental Assessment for the San Pablo National Wildlife Refuge (FWS, 1995).  Data for determining acreage of cities and parks was drawn from detailed local maps (Compass Maps, 1998).

 

Tables and other data cited in this paper were identified through internet sources and through the library of the Sonoma Ecology Center.  Primary internet sources included the Center for Environmental Resources and Evaluation System (www.ceres.ca.gov), the U.S. Department of the Interior’s Environmental Protection Agency’s Surf Your Watershed (www.epa.gov/surf3), and Wetlands Information System (See also www.epa.gov). 

 

Results

The Sonoma Creek Watershed has been severely impacted by development.  The major land uses in the Sonoma Creek Watershed are urban development, vineyards and wineries, and recreational usage (e.g., parks and golf courses).  The recently completed restoration plan for the watershed states that “vineyards are the predominant land use in the upper watershed, particularly on the valley floor” (CALFED, p. 89).  The report also states that “much of the vernal pool, seasonal wetland and oak savanna habitat” previously present on the valley floor has been eliminated as a result of agricultural and urban development.  Figure 2 shows the current state of land development within the lower 75 percent of the watershed, with vineyard acreage based on a sample of 208 vineyards (see Methods for a description of how this data was collected).  The amount of acreage represented in Figure 2 is 8,431.

 

 

Figure 2

 

Table 1  1994 Sonoma Valley Vineyard Acreage by Slope (SSCRCD, 1997)
Percent Slope	Acreage
0-2	3,166
0-5	678
0-9	2,273
2-5	320
2-9	1,379
2-15	954
2-30	32
5-9	15
5-15	565
9-15	686
9-30	83
9-50	142
15-30	2,242
30-50	680
30-75	97
50-75	21

As previously noted, continuing conversion of land to vineyards has led to public concern about erosion, since newly converted land is primarily on hillsides.  Table 1 shows the number of vineyard acres by slope as of 1994.  The table clearly shows that 29.6 percent of vineyards are on slopes of 9-15 percent or greater. Data for new vineyards, or on acreage by slope for the most recent five-year period is not available since most vineyards are privately held companies.  It is expected that the recently enacted Erosion and Sediment Control Ordinance will both retard further development of steep slopes and mitigate the negative impacts of existing planting, future land conversion and replanting.   Futhermore, data on acreage by slope will be collected and become publicly available through the new ordinance.

 

In the very southern part of the watershed, the ecosystem restoration plan (CALFED, 1998) calls primarily for the federal government to either directly acquire estuary and baylands or to gain control through easements.  The land thus acquired would then be included within the authority of the San Pablo Bay National Wildlife Refuge.  This acquisition is important because this land is the last remaining undeveloped area within the watershed.  Table 2 shows the ownership, tracts and acres that have been purchased.  Significantly, the acquired acreage would constitute approximately half of all the existing vineyard acreage within the entire watershed.  This area is shown in detail in Figure 3.

 

 

 

 

 

 

 

Figure 3

 

 

In the past five years 11 major projects and 42 small projects representing 21 public and private organizations engaged in activities to restore some smaller area within the Sonoma Creek Watershed.  The large projects alone account for 5,374 acres.  The major projects focus on wetlands restoration, such as the Ernie Smith Park vernal pools, Sonoma Creek Baylands, and Skaggs Island Wetland Restoration.  Some of the organizations involved with the smaller projects are vineyards and wineries, such as B.R. Cohn, Fichtenberg, and Harywood.  Other organizations include St. Leo’s Catholic Church, Indian Springs Ranch, the Southern Sonoma County Resource Center, and the San Francisco Estuary Institute.  The small projects include eradication of non-native plants and grasses, trail reconstruction such as Arundo Cane, rehabilitation of streambeds and creeks, and wetlands restoration.  As noted, many of these organizations have coordinated their activities through the Sonoma Ecology Center.  Figure 4 identifies the locations of some of the most important projects completed during the past five years or currently in progress.

 

 

Figure 4

 

 

There are also additional large ecological projects within the watershed, but without specific locations identified in spatial format.  These projects, identified through the California Ecological Restoration Projects Inventory (CERPI) and the Watershed Projects Inventory (WPI), are shown below in Table 3.  These projects range in size from 60 acres to hundreds of acres.

 

 

 

 

 

Analysis

Total vineyard acreage within the Sonoma Creek Watershed was 13,333 as of 1994.  This is approximately the total acreage for the entire county in 1960. Using the sample theme of acreage, vineyards range from as small as one quarter of an acre to as much as 625 acres, with the average vineyard being 40 acres. Published data for 1994, the most currently available data for this project, shows that approximately 30 percent of vineyards are on steep slopes, meaning between 9 and 15 percent.  (Current vineyard data, in GIS format, has been provided to the Sonoma Ecology Center, but was unavailable for analysis at this time.)  This trend has become a serious environmental and public relations problem. Unfortunately, comprehensive data, including acreage by slope, is not currently available for vineyard development from 1995 to 2000.  Therefore we are unable to determine either the rate at which vineyard acreage has grown or how much has been on steep slopes. Continued rapid growth of vineyards, however, has caused erosion and led to a public awareness of the need for environmental safeguards.  While much of the watershed has suffered serious over-development in the recent past, it appears this trend is being arrested and positive restorative activities are under way.  The implementation of a Sonoma County ordinance to address erosion specifically associated with vineyard development is one of the major accomplishments.

 

The incorporation of the tidal lands in the southern watershed into the San Pablo National Wildlife Refuge is also a positive step toward restoring the health of the watershed.  The total acquired acreage is about half of the watershed acreage under wine cultivation.

 

Finally, ongoing activities coordinated through the Sonoma Ecology Center will also help eradicate non-native plant species and restore fish animal habitat.

 

 

Conclusion

It appears the Sonoma Ecology Center GIS Project is well on the way to developing an integrated application to document and analyze the long-term impacts on the watershed.  However, much more data needs to be collected and put into spatial format to further identify and evaluate impacts and ongoing restoration activities, such as the eradication of non-native plant species.  In particular, long-term data collection will be required to assess the efficacy of the Erosion and Sediment Control Ordinance on future vineyard development.  Further cooperation among the key land users in the watershed also is needed if success of the restoration plan is to be realized.  Key players would, for example, include the county assessor providing parcel data, the Valley of the Moon Water District providing data on usage by area, or just plain volunteers to convert annotations on topological maps to shape files.

 

 

References

 

Bay Area Watersheds Science Approach: The role of watershed science to support environmental planning and resource protection.  (Version 3).  San Francisco Estuary Institute, September 1998.

 

California Ecological Restoration Projects Inventory (CERPI).  (http://endeavor.des.ucdavis.edu/cerpi).

 

Chorneau, Tom.  “Opponents Fear Loss of County’s Natural Habitat.”  The Press Democrat, November 2, 1999.

 

Map of Sonoma Valley.  Compass Maps.  Modesto, California, 1998.

 

Ecosystem Restoration Program Plan, Volume II (Draft).  CALFED Bay-Delta Program, March 1998.

 

Erosion and Sediment Control Ordinance.  County Agricultural Commission, County of Sonoma, December, 1999).  (Note: A copy can be obtained from the following website:  http://www.sonoma-county.org).

 

Final Environmental Assessment for the Proposed Additions to San Pablo Bay National Wildlife Refuge: Solano, Napa and Sonoma Counties.  Fish and Wildlife Service, U.S. Department of Interior, August 16, 1995.

 

Richard Hertz Consulting.  “The Press Democrat Poll on the Wine Industry.”  Published in the Press Democrat newspaper, November 3, 1999.

 

Sonoma County Grape Grower’s Association.  Sonoma Valley Appellation Regions.   Poster produced by Circuit Rider Productions, Sebastopol, California, 1999.

 

Sonoma Creek Watershed Enhancement Plan.  The Southern Sonoma County Resource Conservation District.  Sonoma, California, June 1997.

 

Sonoma Ecology Center GIS Project.  Sonoma, California.  (Can be reached at http://www.ceres.ca.gov/sec/gis.html or http://vom.com/sec/gis/gisgps.htm).

 

Weiser, Matt.  ‘Vineyard Law OK’d Despite Protests.”  The Press Democrat, October 13, 1999.

 

Wetland Projects Inventory (WPI). (Can be reached at http://www.nwi.fws.gov)  (Also see http://endeavor.des.ucdavis.edu/wpi).