DPR/CAC Permit Mapping Developers Group
Recommendations for Site Definition and Identification
April 1998, Modified April 2000

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The Department of Pesticide Regulation’s Permit Mapping Developers Group has drafted the following recommendations for County Agricultural Commissioners wishing to implement a Geographic Information System (GIS) as a tool for mapping and tracking pesticide permitting and use at the county level.

In order to bring a level of statewide consistency and uniformity to permitting and use reporting the following recommendations and guidelines for identifying sites should be implemented when using GIS. These guidelines have been developed by the Permit Mapping Developers Group, which is made up of staff from DPR’s Information Systems Branch and CAC staff who have begun to implement GIS systems in their respective counties. The guidelines are intended to bring a level of standardization to the system for analytical purposes, both at the county and state levels. Adherence to these recommendations should substantially reduce misrepresentation of the data, i.e., the appearance of duplicate records, and confusion as to which use report goes with which site.


Site--a contiguous area which has only one operator and undergoes the same pest management and cultural practices, preferably consisting of a single commodity or use at a time. Exceptions to this definition include (a) interplanted commodities and (b) sites less than "x" acres in size. The value for the most manageable minimum acreage will be left to the discretion of each Commissioner.

Contiguous--a property whose boundary is not broken by public road(s), rights of way, or permanent waterways. Each Commissioner would identify permanent waterways and rights of way in their respective counties.

Site id--the "label" used to identify the site.

Permit Number, sometimes referred to as the Operator Identification Number (OIN)--

  • should not be reissued by a county within the same calendar year.
  • should follow a modified version of the existing format, e.g., 10 1997 10 00001
    • 10.......................................issuing county
    • 1997...................................year (2000 compliant)
    • 10.......................................home county of permit holder
    • 00001.................................grower serial number
  • The last 5 digits (e.g., 00001) should be unique and issued by the CAC.
  • The last 7 digits (e.g., 1000001) should be unique statewide, so that they can be used in any county where the grower obtains a permit (no change from current practice).

Site id--can reflect a naming or labeling scheme used by either the grower or the CAC. It should provide relevance to the grower, the county, and others. However, in combination with the Permit Number, it should be unique to the ’site’ it represents as this refers to a place on the earth’s surface and not the commodity which is grown on that piece of ground.

  • The site id does not need to change when crops are rotated on the site as long as the field boundaries do not change. Following this rule will significantly reduce ongoing workload associated with the GIS/permit updates in those counties crops are grown on short rotations (8-12 weeks). See "subsequent plantings of the same crop" below.
  • The site id should not be reissued to the same permit holder within the same calendar year when changes to the site occur, e.g., property is sold and permit holder leases or buys new ground. A new site id should be issued for the new site.
  • A new and unused site id should be issued when changes to the site boundary occurs. If sites are split, the newly formed sites must have different site ids from the original site.

Interplanted commodities--should have the same permit number and site id in order to identify the different crops/uses as being grown on the same piece of ground. The commodity/use name would be used to differentiate between pesticide applications to each crop or use.

Subsequent plantings of the same crop--within the same calendar year where no site boundary changes occur should be identified by sequential letters or numbers stored in a single character field in the PUR. For example, a, b, and c would differentiate three sequential plantings of the same crop on the same site.


In response to issues and concerns raised by various CAC staff, the Permit Mapping Developers Group has made the following recommendations for the best solutions based on a reasonable GIS approach.

How to represent an application to part of a site (spot treatments, strip spraying)? Unless the information is supplied to the CAC by the grower, the Group recommends that CACs use data from outside the scope of GIS and the permit/use report programs. The group does not consider tracking pesticide use at this level to be reasonable at this time given the level of personnel and resources in most counties.

How to deal with very small acreages which have constantly changing commodities and orientations? Mixed plantings of short duration crops need to be identified in a way that balances the quality of data with the quantity of work required to capture it. Each Commissioner should decide what level of detail will allow growers to show CEQA equivalency, provide sufficiently accurate tracking detail to meet the CAC’s needs, and yet not be overly burdensome to CAC staff and growers.

How to deal with large acreages (>640 acres) of the same commodity under a GIS system. Using GIS allows sites to be related to a piece of ground, so it is no longer necessary to rely on sections as a means of identification. Therefore there is no need for site boundaries to be contained within a single section, removing the limitation of 640 acres and allowing sites to cross section lines if necessary. GIS will allow section based data such as PMZs to be superimposed over site information, and so spatial analysis can be used to identify sites that fall within sections that have these designations.

Whether to track pesticide use at block or site level. It is recommended that counties and growers identify fields/crops in the permit and the pesticide use report at the block level. This will improve the quality of the program in general, provide the CACs with better information for decision making and CEQA evaluations, and provide more accurate pesticide use information. If growers are willing to provide information to the CAC at the block level (many are tracking at this level now), then the CACs are encouraged to use this preferred method of identifying sites if adequate resources are available in the county.

Final Notes...

These guidelines and recommendations have been made in order to help CACs optimize the return of an investment in GIS. However, the following points should be considered when making a decision as to how much information is really necessary:

  • Flexibility; discretion of county to determine what is reasonable and manageable within resources
  • Point of diminishing returns; recognize the limitations and costs to collect the data
  • Loss of compliance by industry if too detailed and burdensome
  • Loss of data quality and accuracy if too detailed and burdensome
  • Recognize that there are limits on what the "data" in a database can represent
  • Cannot design a system which meets all needs and uses
  • Identify program priorities, data requirements, and uses of the data
  • Start with the identification of sites which have permanent, perennial crops/commodities/uses
  • Don’t use GIS for rights of way, ditch banks, and applications to field boundaries
  • Guidelines may need to be different for small, short-duration crops versus permanent commodities
  • Evaluate impact of any changes on industry, including modifications to their software and computer systems