Technical Report

Room to Grow?

As Humboldt County has engaged in the process of updating its General Plan for guiding development through the year 2025, one of the most contentious issues that has emerged is the availability and location of available land to accommodate expected future population growth. In addition, two major concerns have emerged from the public participation efforts conducted for the Plan update: (1) the desire to protect the county’s remaining agricultural, timber, and open space lands from future conversion to other uses; and (2) a desire to address the county’s lack of affordable housing. The research presented here attempts to illustrate how various development, land-use policy, and population growth assumptions interact with one another in estimating the capacity of the county to absorb future population growth. Such analysis also allows the public, planners, policy makers, and elected officials to use the best information to decide the optimum mix of future land-use policies for Humboldt County that will balance desires and needs for meeting future population growth, providing more affordable housing, and protecting existing resource production and open space lands. Through the use of a new interactive computer software tool – called CommunityViz® - these issues can be examined for a virtually infinite number of hypothetical scenarios. The software, designed and distributed by the Vermont-based Orton Family Foundation, uses satellite photographs, global positioning data and development plans to analyze various alternative development scenarios and display them in a three-dimensional format. Numerous rural counties and towns throughout the country have used the software in similar modeling analyses. We used this software, along with data layers from Humboldt County’s GIS-based land use inventory and population data and estimates from the U.S. Census Bureau and California Department of Finance, to analyze likely population growth and development scenarios for Humboldt County’s future. Throughout our analysis, we explain explicitly what data and estimates are used, how we use them, and how we addressed any challenges that arose in adapting the data for our analysis. We developed eight future, hypothetical population growth and development scenarios for Humboldt County through the year 2025 for analysis and comparison. We feel these scenarios represent a reasonable range of options for Humboldt County’s future based on past and projected population growth, development density, and land-use trends. Each of the scenarios shares a set of common assumptions, such as the amount of land excluded due to various development constraints and the proportion of future population growth that will occur in unincorporated areas of Humboldt County. All of the scenarios forecast population growth and development through the year 2025, since this is the target year the county is using in their General Plan update. The purpose of this analysis is not to advocate any particular scenario for how the county should accommodate population growth and development in the next few decades. Rather, we wish to illustrate the implications of various assumptions and hypothetical planning decisions and to demonstrate the potential that the CommunityViz® modeling software has to assist planners, policy makers, and the public in making more-informed decisions involving future development patterns in Humboldt County. When we analyzed and compared the scenarios, the most important finding is that under the most likely future population growth and development scenarios, Humboldt County can easily accommodate growth with moderate housing densities on existing residentially-zoned lands within existing sewer and water serviced-areas while protecting agricultural, timber, and open space lands. This is true even when excluding 60 percent of the total available land due to various development constraints. And, this development would not have to occur at a density level that residents would likely find incompatible with the “rural” character of Humboldt County communities: 90 percent of the development could be accommodated with a mix of large-lot suburban homes and large lot rural estate-type development. For example, using the annual population growth rate forecast by the State – 0.5 percent per year – and an average density of 5 units built per acre, 8,273 housing units could be accommodated but only 3,354 units are needed. Thus, there is a substantial surplus of available land, even when development is limited to existing sewer and water-serviced areas and significant development constraints are factored in. The results also show that even if the population growth rate turns out to be significantly higher than the current forecast by the California Department of Finance, that growth could still be accommodated without converting substantial amounts of agricultural, timber, and open space lands. For example, if the population growth rate turns out to be twice the rate predicted by the State (1% vs. 0.5%), in the scenarios we evaluated, there is more than enough land to accommodate the increase. If the growth rate turns out to substantially higher than current State predictions (four times higher, or 2% vs. 0.5%), this rate of population growth could still be accommodated without a significant expansion onto resource production and open space lands by increasing density of new development (such as by increasing the average density of development to 10 units per acre, as we evaluate in two of our scenarios), or by moderately expanding development outside of current sewer and water-serviced areas. Another key finding from another of our scenarios shows that if we keep developing at densities similar to what the County has permitted between 1985-2000 (approximately 1 housing unit per 10 acres), we will fall far short of projected housing needs: we would need to build 3,354 housing units, but we could only build 166 units (less than 5 percent of the need) at historical density levels. In order to meet the projected housing need under this scenario, over 30,000 acres outside of existing residentially-zoned land in sewer and water district-serviced areas would need to be developed. Clearly, if the public and County decision-makers desire to protect substantial amounts of resource production 5 and open space lands, and if they want to provide more affordable housing opportunities1, future development will need to be built at a higher density than what has been permitted in the recent past. If new housing is built at the moderate average density (5 units per acre) that we use in many of our development scenarios, it is likely that in addition to the benefit of preserving existing agricultural, timber, and open space lands, there will be substantial economic benefits as well. For example, many infrastructure costs (such as roads, sewer and water lines, police and fire protection) will likely be substantially lower if new development is built within and adjacent to existing developed areas and at a higher density than the extremely-low average density that was permitted between 1985-2000. Also, such housing is likely to be more affordable as many lot sizes will be smaller than historical development patterns, significantly reducing one of the key components of housing cost (cost of land). These benefits would increase if a higher average density of development is chosen, such as the average density of 10 units per acre that we analyzed in two of our scenarios. Our use of the CommunityViz® software package for this analysis provides a transparent method for analyzing various growth scenarios. Although we have made every effort to be extremely detailed and specific about the methods and data used, one of the strengths of the software program is its ability to change assumptions “on-the-fly.” Therefore, if some of our facts or figures are disputed by readers and reviewers of this report, we hope to use this software to work with groups and individuals to illustrate the implications of different assumptions and hypothetical planning decisions. Thus, we hope that the results presented here will lead to future, productive discussions on how to accommodate future population growth while protecting the rural qualities that make Humboldt County such a special place to live.