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Plan Selection

The County's intent expressed in this Management Plan is to be able to meet future aggregate needs using the resources that are available or could be developed in the County while recognizing that continued production from both terrace and instream sources must be regulated with standards that avoid or minimize significant impacts and promote the efficient use of the resource. The Management Plan presents policies and procedures that will result in a balanced development of the County's aggregate resources that recognizes all of these factors.

The options for quarry, instream, and terrace production presented in Chapter 6 and the combinations of options that could meet the projected demand for aggregate were examined as a basis for selecting this Management Plan. In order to manage the County's aggregate resources and achieve the goal of meeting aggregate demand while minimizing environmental impacts and land use conflicts, the Management Plan combines a number of the policy elements of the options and alternatives presented in Chapter 6, and allows all three types of aggregate mining under certain conditions. Continued reliance on the 1980 ARM Plan, one of the alternatives considered, does not solve the problems that have been experienced with terrace reclamation or instream gravel operations. On the other hand, reliance only on quarries to meet all of the County's needs appears unrealistic at this time because of the lack of proven availability of sufficient high- quality resources to meet projected demand. The Plan thus continues the "mixed-source" strategy adopted in the 1980 ARM Plan but firmly redirects future aggregate production to hardrock quarries.

The major new features of this Plan include:

  1. Increased incentives to stimulate quarry production from existing and new sources, particularly for PCC and other "high quality" uses.
  2. Continued instream extraction for flood and erosion control with more protection for fisheries, wildlife habitat, and adjacent uses.
  3. Stricter short and long-term limitations on terrace mining.
  4. Stronger support for recycling of aggregate products and reduction of aggregate demand.
  5. Review and amendment of aggregate specifications to increase use of quarry materials while assuring product quality.
  6. A major shift in terrace mining reclamation from required agricultural restoration to a combination of recreation, wildlife habitat, and agricultural reclamation, including accelerated reclamation of existing pits which have not been adequately reclaimed.
  7. More comprehensive operation and reclamation standards for all mining.
  8. Addition of a road mitigation program and fee.
  9. Addition of a fee on Russian River terrace and instream mining for impact mitigation programs.
  10. Increased monitoring of mining activities and reclamation progress.

The Management Plan incorporates some of the elements of the environmentally superior alternative identified previously in Chapter 6. It attempts to stimulate quarry production so that terrace production can be terminated after ten years.

Instream mining, in the form of gravel bar skimming, will continue to be allowed at levels which balance the rate of aggradation and degradation. It will also be allowed to protect adjacent uses from flooding and bank erosion, but the revised standards will further reduce and minimize the effects on channel levels, vegetation, wildlife, and fish. The Management Plan also advocates reducing the overall demand for Sonoma County aggregate by encouraging the use of recycled materials and alternative sources.

While quarry production has increased since the development of the 1980 ARM Plan, it is not adequate to supply all of the existing needs, particularly the needs for PCC. The County actions proposed in the Management Plan will be needed to stimulate the expansion of existing quarries and their production and to develop new ones. One idea proposed for further consideration is that the requirements for aggregate could be changed so that quarry sources are used in place of instream and terrace sources. While the performance specifications discussed in Chapter 2 do not necessarily prevent the use of quarry rock, the existence of plentiful and less expensive alluvial resources means that these sources are selected for uses where quarry rock could work as well. Changing the preference for alluvial sources will continue to take time, and the County will need to take the lead in this effort by changing its purchasing practices and establishing policies to require more use of quarry rock and make it more competitive.

The Management Plan provides enough mining sites and aggregate resources that future demands for aggregate uses can be met through the year 2010 and beyond. The demand projections in Chapter 3 indicate that the 1991 to 2010 demand for all Sonoma County aggregate will range from a low of 75 MT (million tons) to a high of 175 MT. The projected demand range for construction-grade aggregate for the same period is 52 to 118 MT. Using a moderate estimate of future demand, the Management Plan anticipates the following needed production from 1991 through 2010:

  • Construction grade aggregates = 75 MT
  • Other aggregate materials = 35 MT
  • Total aggregate needed = 110 MT

It should be emphasized that these figures are estimates of long-term demand, not definite production requirements. The Management Plan recognizes that actual demand and production during this period may be more or less than estimated, depending upon a number of factors, including regional growth, development standards, aggregate recycling and reuse, market trends, and permit approvals.

The Plan anticipates that the long-term demand will be supplied primarily from existing and new quarries. Instream mining will supply a consistent but low portion of the demand for high quality materials. Terrace mining will supply a smaller portion of the long-term demand than in the past because terrace operations will be terminated in ten years. Terrace resources will be allocated very cautiously for a limited time to meet needs for PCC and high-quality uses until quarry sites are explored, permitted and developed as a replacement source.

As a result of the Plan proposals and the moderate demand estimates, the Plan anticipates the following demand and production quantities:

Construction GradeNon-Construction


Quarries47 MT35 MT82 MT
Instream8 MT08 MT
Terrace20 MT020 MT
Total75 MT35 MT110 MT

Given the uncertain nature of the market in the future, the potential for increasing the production from quarries, and the potential for increased use of recycled and substitute materials, the Management Plan provides for sufficient production to meet the range of identified needs. The satisfaction of demand for PCC and other high-quality uses will be further assured by the Management Plan provisions to periodically re-evaluate supply and demand factors and management policies as necessary.

All mining activities result in environmental impacts and can create land use conflicts. Often, these impacts can be reduced or fully mitigated, but aggregate operations generate some significant impacts that cannot be entirely avoided or reduced to non-significant levels. The Management Plan incorporates Mitigation Measures identified in the Program EIR in the form of mining and reclamation standards and other policies and implementing actions. Implementation of these measures is expected to reduce characteristic environmental impacts to acceptable levels. However, environmental review of specific mining and reclamation proposals on individual sites may result in imposition of additional measures to mitigate site-specific impacts not addressed in the Program EIR.

Mining operations in the Russian River, Austin Creek and the Gualala River shall be required to comply with the mitigations identified in the Program EIR and adopted as mining and reclamation standards in the ARM Plan unless other mitigations and/or mining standards are deemed to be more appropriate pursuant to a site- specific environmental review in light of unique environmental conditions, past monitoring results, changing channel conditions and new regulatory requirements and such other mitigations and standards are authorized in the approved Use Permit and Reclamation Plan.(Revised September 28, 2004 Resolution #04-0917) (Revised September 16, 2008 Resolution #08-0777) (Revised December7, 2010 Resolution # 10-0843)

Contact Information

Contact Planning by Phone
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Santa Rosa, CA 95403
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