Underestimation of El Dorado Hills population and traffic growth:
An essential basis for public policy

Tracking and forecasting population is particularly important to El Dorado Hills because at least half of all new housing development in El Dorado County has gone to EDH in roughly the past decade.

The following two graphs illustrate variability in estimates of El Dorado Hills population. The first graph is mainly based on records from recent history. The second is partly conjectural, to project a range of possibilities for 2035 based on that historic data. Both graphs use a resolution of 5 years per plotted data sample.

Population also reflects growth in locally generated traffic.  Since El Dorado County General Plan anticipates 3 trips per day from each household for single family homes and population is approximately 3 times the number of households, the graphs can also be interpreted as showing total daily trips generated by local population.

From 2000 to 2005 El Dorado Hills population grew at about twice the rate forecast in the El Dorado County 2004 General Plan.This growth rate began declining, then crashed to virtually zero in the economic crisis caused in part by home finance and market factors.

Graph 1 (above):  Based on actual data where possible, extrapolated and interpolated where necessary due to sparseness of data samples.

Resolution is one data point per 5 years. Actual data for the Fire Department ("El Dorado Hills County Water District") and the El Dorado Hills Community Services District covered years through 2009. Census data was recorded for 1990 and 2000.  The final data point from SACOG was from 2003.


 

Graph 2 (above):  Conjectural projections beyond 2010  based on Graph 1. This is intended to illustrate the range of results produced by different rate estimates and to provide a sense of the reciprocal relationship between time-to-given-population and growth rate. This does not suggest that any particular one of these is an entirely valid forecast: Growth rarely has a truly linear growth rate and tends to be highly cyclic.

Buildout population based on the 2004 General Plan and its stated land use limit on housing units is:

• 73,718 at 2.8 persons per housing unit  (assumed by General Plan)
• 78,969 at 3.0 persons per housing unit  (assumed by Fire Department)
• 86,882 at 3.3 persons per housing unit  (assumed for El Dorado Hills by current County Zoning Code, probably from 2000 Census data)

The County General Plan identifies a fixed number of housing units based only on its Land Use map. It does not account for additional housing units permitted by developer use of the General Plan's policies for density bonuses. Full use of density bonuses can increase housing unit density by up to about 30%.

All projections in Graph 2 are linear extrapolations at constant growth rates, except for separate SACOG-published data points for years 2025 and 2035. No attempt is made model asymtotic approach to buildout. It is also possible that the buildout level could be changed by future amendments to the General Plan and the Zoning Code,most likely to permit additional growth.

The four alternatives in Graph 2 have these characteristics for a buildout population of 80,000:

Projection	Growth rate used for extrapolation	2009/10 % error	Year of buildout	Population in 2035 without buildout limit	Description of projection
Fire Dept A (blue line)	1,607 persons/year	~ 1%	2033	82,790	Growth at approximate overall rate of SACOG growth projected by SACOG for 2010-2035,
Fire Dept B (red line)	3,149 persons/year	~ 1%	2022	121,300	Growth at rate recorded by Fire Department 2000 - 2009, projected forward  from 2010
Fire Dept C (yellow line)	3,149 persons/year	+ 29%	2018	134,127	Growth at rate recorded by Fire Department 2000 - 2009, projected forward from 2005
SACOG (purple line)	1,270 persons/year 2000-2025 1,616 persons/year 2025-2035	-31%	2045	64,835	Growth at rates reported by SACOG, mainly from 2003 & 2007 documents

Notes on Data sources and primary data

The most reliable population data has been from two public agencies which receive per-household property tax revenue.

• The El Dorado Hills Fire Department ("El Dorado Hills County Water District") covers most of the area recognized in the 2010 Census as the El Dorado Hills Census Designated Place. In each annual report the Fire Department publishes bar graphs and data for a 10-year history of housing units and population, with population estimated at 3.0 times the number of housing units.
   
• The El Dorado Hills Community Services District periodically publishes a report of its district's population as certified by the California Department of Finance. The CSD covers a moderately smaller district than the Fire Department.

Other data sources have been problematic.

• With El Dorado Hills as an unincorporated area, its population is tracked infrequently by county, regional, state, and national agencies. Aside from the Fire Department and CSD, In the past decade the main sources of data have been the 2005 studies for the attempted incorporation of EDH as a city and sparse line items in documentation for the 2004 General Plan. Census data is updated only every 10 years. SACOG data for EDH is very sparse, and on balance SACOG may be more of a consumer than a producer of primary data from original sources.
   
• As an incorporated area, when data is published it has generally covered only a portion of the El Dorado Hills community area, whose limits tend to be defined more by the road network than by geography. The Census Designated Place was especially undersized in 2000 and 1990, but has been updated in the 2010 Census to an appropriate scope, approximately matching the El Dorado Hills County Water District (Fire Department) boundaries.
   
• Some data from the past decade appears to have been biased to favor development, especially in the El Dorado County 2004 General Plan. This was in the context of historic contention between low-growth and pro-growth opinion in the County, and especially in El Dorado Hills. One indication is that a source within the County Planning Department noted "There was a lot of Supervisor direction around that time" in answer to a specific question on this topic. Another was the documented action of the Board of Supervisors in choosing a base alternative for the General Plan. Despite the Planning Commission's recommendation for a compromise, the Board combined elements of different alternatives to maximize population growth while minimizing road infrastructure growth.
   
  Another evident form of bias was choice of 1999 as the base year for "existing condition" analysis in the 2004 General Plan. 1999 was the last year before EDH development increased to a much higher rate than in the 1990s, especially in the then-new Serrano development, but also in several other Specific Plan areas.
   
  Yet another factor was that the General Plan used density calculations based only its Land Use map densities. It did not account for additional population enabled by new General Plan policies for density bonuses. Those density bonus policies have now been used to authorize a number of developments in the northeast part of EDH which produce significantly higher densities than the Land Use map permits.

To date this writer has found only one published acknowledgment of understatement of EDH growth rate. One SACOG document from 2004 includes a bullet item stating "The previous projections underestimated the amount of growth in the Natomas Basin, Southwest Placer County, and El Dorado Hills.". This is in Projections Update, Metropolitan Transportation Plan 2027, dated December 16, 2004.

It does not appear that later SACOG documents recognize the population understatement noted in 2004. The MTP 2035 document, dated March 20, 2008, in Appendix D2 says that "... The recipients of this development – the unincorporated communities of El Dorado Hills and Cameron Park – are expected to become the primary population and job centers of the County by 2035."  El Dorado Hills reached that status several years ago. EDH now (2010) has more than 4 times the population of the City of Placerville, easily exceeding that of both of the County's incorporated cities combined.  Population of the combination of EDH and Cameron Park probably is now in the range of 60,000 to 65,000, roughly matching that of the City of Folsom.

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