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Disclaimer: We acknowledge the inherent margin of error in any scientific assessment. These polygons would be drawn differently by different people. We are confident, however, that SJWC is sufficiently over the limit for allowable timberland that our margin of error is inconsequential. Please see below for our calculations of potential error.

To see all the supporting evidence, maps and photos of these results, please see the "Evidence Section ".

By our most conservative estimate, San Jose Water Company owns 2748 acres of unequivocal timberland. This estimate includes 2733 acres of land that contain obvious evidence of mature Coast Redwoods and Douglas-fir trees. Additionally, it includes several "Out Areas" that are within the boundary of the NTMP (total 14.8 acres) that had been cleared, subjected to a recent landslide, or are mostly dominated by hardwoods. All of these acres are backed up by the photos we have presented in the "Evidence" section. For a complete map of these areas, see Map 1.

We would like to emphasize that these 2748 acres must be, by definition, less than the actual amount of legal timberland owned by SJWC. The CDF definition of timberland also includes areas of Group B species (e.g. Tanoak, Pacific Madrone, Eucalyptus) that: 1) may have grown Group A species in the recorded past 2) may have Group A saplings present, or 3) may have the capability to grow to Group A species. Finding such areas of Group B species that may qualify as timberland would require ground-truthing on SJWC land, thus we have prepared a tiered analysis of Timberland owned by SJWC ranging from the most conservative to the most liberal interpretation of the definition of "Timberland".

Following the table is a detailed explanation of each estimate and the rationale.

Total Acres
Percent of Known SJWC Land
Acres owned by SJWC that are physically occupied with Coast Redwood and Douglas-fir trees (Group A acres)

Timberland Estimate 1

(Group A acres + 14.8 acres of out areas)


Timberland Estimate 2

(Group A acres + 100 meter buffer into adjacent hardwood forest areas)


Timberland Estimate 3

(MROSD Mapping + Unmapped Areas with Group A)


Timberland Estimate 4

(Acreage of SJWC Parcels with over 50% Group A species)


Timberland Estimate 5

(Acreage of SJWC Parcels with any Group A species)


Timberland Estimate 6

(Derived from CDF Land Cover Mapping and Monitoring Program)


Margin of Error: We cannot calculate standard statistical error for these estimates because of a lack of reference points. We can account of the possibility that we over-estimated the area of Group A species (i.e., that our polygon lines extend too far outside of the zone of actual conifers). If the outside area of each polygon was reduced by 10 meters in zones that border other vegetation types, the total acreage of SJWC land occupied by Group A species would drop to 2617 acres, conversely it could be as high as 2845 with an expansion of 10 meters. Following this rationale, our margin of error would be about 4%.

Estimate 1) There are many acres owned by SJWC which contain Group B species such as Tanoak and Madrone and may have either young Douglas-fir in the understory or old Coast Redwood stumps, but we cannot determine the presence or absence of these areas. Thus our most conservative estimate includes only areas with obvious Coast Redwoods and Douglas-fir and the "Out Areas" within the NTMP zone. A review of old photographs might provide evidence of more extensive conifer forests in the past. (Total: 2748 acres)

Estimate 2) Areas that were historically on the margins of dense conifer forest may still be recovering from a clear-cut in the early 20th century, followed by the Austrian Gulch fire in 1961 and then the Lexington Fire in 1985. Douglas-fir and Coast Redwoods are often referred to as climax species that can be facilitated by intermediate successional stages of hardwood forest within certain climatic ranges. We acknowledge the fact that the idea of a climax species has been criticized in recent ecological literature, and that any assessment of successional states depends on assumptions about the natural fire regime, but the idea of an dominant species is still widely used in silvicultural programs and CDF literature. Therefore, there may be many areas of SJWC land that are dominated by hardwoods currently (California Bay Laurel, Tanoak, Pacific Madrone) that have not returned to their pre-clear cut state. Supporting this idea is that fact that we found many areas of young Douglas-fir coming up in otherwise hardwood zones that had not been observed in the vegetation mapping completed by Midpeninsula Open Space Regional District in 1999. Supplements 5 show pictures of a few of these transitioning areas. Supplement 6 shows evidence of the dead conifer skeltons extending into what are currently chaparral areas. Also, Appendix 2 discusses the ecological rationale for this idea in detail and includes quotes from the NTMP that are consistent with this idea.

Most Douglas-fir seeds are dispersed by wind or gravity, and fall within 100 meters of the parent tree (Uchytil 1991, Barnes and Honkala 1990). Most Coast Redwood seeds fall within 60-120 meters from the parent tree (Griffith 1992, Barnes and Honkala 1990). This estimate thus includes all areas with obvious Group A timber species plus a 100 meter buffer zone into any adjoining forest community (California Bay, White Alder, Tanoak, etc) that is still within SJWC land. This 100 meter buffer is meant to represent land that could be colonized by Group A species within one conifer generation given typical seed shadows. (Total: 3428 Acres)

Estimate 3) Midpeninsula Open Space Regional District (MROSD) mapped vegetation types on some SJWC land, albeit at a coarser scale and with a different goal than our mapping. This estimate includes any area mapped by MROSD with a vegetation type that includes Coast Redwood or Douglas-fir as a common species, per the definitions provided by the Manual of California Vegetation. Since some areas owned by SJWC were left out of the MROSD mapping effort, we have also added Group A acres that we found on unmapped areas. For more on the correspondence between the MROSD mapping and our data, see Appendix 1. (Total: 3922 Acres)

Estimate 4) Legal arguments about the definition of "Timberland" may be based on parcel ownership, not on ecological criteria. This estimate is the sum of the acreage of SJWC parcels on which over 50% of the land is occupied by Group A timber species that are large enough to be identified in aerial photographs. The specific APN numbers for these parcels is listed in Supplement 3. (Total: 3085 Acres)

Estimate 5) This estimate is the sum of of the acreage of SJWC parcels which contain any amount of Group A timber species. This may be an underestimate because it does not include land with only newly establishing Group A species that are not visible in aerial photographs. The specific APN numbers for these parcels is listed in Supplement 3. (Total: 5719 Acres)

Estimate 6) The Land Cover Mapping and Monitoring Program (LCMMP) is a joint effort of the California Department of Forestry and Fire Protection and the USDA Forest Service. This program is highly regarded, it derives land cover data from Landsat Thematic Mapper (TM) satellite imagery and is updated every five years on a rotating basis . According to the latest dataset, the land owned by SJWC is comprised of 327 acres of pure conifers, 2434 acres of mixed forest (conifers and hardwoods), 1710 acres of pure hardwood forest, and 1879 acres of shrubs (the rest of the acreage is made up of small units of water, herbaceous plants and 'urban' areas). The sum of the pure conifer and mixed conifer classification amounts to 2761 acres, which is very similar to our mapping of conifer species on SJWC land.

Proceed to Authorship Statement or Appendix 1 or Appendix 2