Usenotes for Dept of Pesticide Regulation 1995 Pesticide data

Pesticide use data is for 1995, and is provided by the California Department of Pesticide Regulation (DPR).  

A full description of all fields in the original tables obtained from DPR can be found in the Adobe Acrobat document titled "doc_95.pdf" in the WATER3\Pesticid directory.  This document can be read using the Adobe Acrobat reader available for free from Adobe's web site (search for Adobe using Yahoo or any other browser).  A supplementary file called "errata95.txt" can also be found in the WATER3\Pesticid directory.

The original data can also be obtained directly from DPR by contacting Bev Martin at (916) 445-4046.  As of the date of this note, DPR has begun releasing the data on CD-ROMs for about $60-$70.  This would be an obvious route to go if you are interested in obtaining 1996 data when it becomes available.

BASIC USE

The pesticide use data has been assembled into two ArcView 3.0 projects called "pestuse1.apr" and "pestuse2.apr", both of which can be found in the WATER3\Pesticid directory.  The tables within both projects are quite large, so don't be surprised if either project takes several minutes to load.

Pestuse1.apr is set up for two types of initial analysis: identifying where particular pesticides or chemicals were applied in 1995, and identifying crop types for those areas where pesticides were applied.  Specific instructions for these two analyses are provide below.  

PestUse2.apr is set up to allow you to identify which pesticides were applied in a selected watershed or set of watersheds.  Again, specific instructions for how to do this are provided below.  

Of course, many additional analyses can be developed in either of these projects based on re-arrangements of the data (e.g., different links between tables) and by adding additional themes (e.g., streams, precipitation, etc.). 

Both projects contains a view (View 1) showing the area for which 1995 pesticide application (use) data were obtained for the WATER project, and several tables with pesticide use-related data.  The geographic region covered in both projects includes the following counties:

	Marin County
	San Francisco County
	San Mateo County
	Santa Clara County
	Santa Cruz County
	San Benito County
	Monterey County
	San Luis Obispo County  

Since DPR's pesticide application data is georeferenced to the Public Land Survey System (township, range, section), that is the finest level of detail available for showing the location of particular pesticide applications.  Thus, any particular application can be geolocated at best to an individual section, which is typically one mile by one mile in size.  Although DPR does record the application of pesticides to smaller areas (individual fields) within sections, these smaller areas are not mapped yet in a GIS.  Nonetheless, the spatial scale of the PLSS does allow analysis of at least regional and often watershed-level use patterns.

The tables shown in "pestuse1.apr" and "pestuse2.apr" are slightly re-arranged from what was originally received from DPR, in that some of the tables have been combined to show more information in fewer tables.  While this takes more storage space, the result is fewer tables and faster querying.  (The recombining of tables was performed in MS Access, and tables were exported as tab-delimited text files that can be read by ArcView.)

THE PESTUSE1 PROJECT

As noted above, the Pestuse1.apr project is set up to make it easy to perform two basic types of analysis:

1) Where was a particular pesticide or chemical applied in 1995?

To run this analysis for a particular brand of pesticide (e.g., "Roundup Herbicide"):

a.) make the chemcomp.txt table active. (by clicking once on the gray bar at the top of the table's window)

b.) click on the query builder button (the one with a hammer and questionmark on it)

c.) build your query by double-clicking on "[Product_na]" on the left, then clicking once on the "=" button, then double-clicking on the product name you are looking for in the list on the right.  

d.) Click the "New Set" button.

In a few minutes (there are lots of records to check), your pesticide  will become highlighted in the chemcomp.txt table.  At the same time, View1 will highlight in yellow all the places that your pesticide was used and reported to DPR in 1995.

You can do the same analysis for a particular chemical component (which may be found in more than one brand of pesticide) (e.g., Diazinon or Malathion).  Do do this, query the chemcomp.txt table as above, but using the field "[Chemname]" instead of "[Product_na]".  This will show you all the areas where that chemical was applied and reported to DPR in 1995

2) Where was a particular type of crop grown (e.g., strawberries)?

To run this analysis:

a.) first, make sure no records are selected in any of the tables.  (to unselect records in any table, make the table active and use the Edit... Select None menu item).  This will clear any highlighted records from a previous analysis.

b.) make the uses.txt table active. (by clicking once on the gray bar at the top of its window)

c.) open the query window by clicking on the query builder button (with the hammer and questionmark on it).

d.) choose "[Site_name]" from the list on the left by double-clicking it.  Then click once on the "=" button, then choose the crop or use you are interested in from the list on the right by double-clicking on your selection.  Hit the "New Set" button.

The computer will whirr for a while, then you will see on View1 all of the areas where pesticides were reportedly used on that crop in 1995.  When interpreting this information, keep in mind that you are only seeing those areas where pesticide use was reported for the year 1995.  This does not include areas where the crop in question was grown without the use of pesticides.     


THE PESTUSE2 PROJECT

The PestUse2.apr project is set up to allow you to easily see what pesticides and chemicals have been applied in a selected watershed or set of watersheds.

To perform the analysis, follow these steps:

1)  Open the PestUse2.apr project and make sure View 1 is active.  (by clicking once in the gray bar at the top of the View 1 window.)  If you like, you can zoom in to the area or watershed you are interested in.

2)  Make the "Select Feature" tool active.  (by clicking once on the fourth tool button from the left on the second row of tool buttons.)  Make the Hydrologic Subareas theme active.  (by clicking once on the theme's name in the legend to the left of the map view.)

3)  With the "Select Feature" tool active, and the Hydrologic Subareas theme active, click in the watershed (or drag a square touching the watersheds) you wish to analyze.  The red stippling should turn yellow to indicate which watershed(s) are selected.

4)  Now make the PLSS grid (Public Lands Survey System) theme active.  (by clicking on its name in the legend.)

5)  Use the menu item Theme... Select by Theme to open the Select By Theme window.  

6)  In the first droplist, choose "Are Completely Within", and choose "Hydrologic Subareas" from the second droplist.  This will ask the computer to select all the features of the active theme (the PLSS grid) that are completely within the watershed(s) you previously selected from the Hydrologic Subareas theme.  (Note that you could also have used "Intersect" as the choice from the first droplist.  This would have selected all the PLSS sections that are at least partially within the watershed (i.e., those completely within PLUS those on the edge of the watershed).  Either way, you will need to remember that the results will either under-represent or over-represent the actual area within the watershed.)

7)  Click on the "New Set" button.  

The computer will whirr for a few minutes as it looks for the correct records.  The appropriate grid sections will turn bright yellow, along with the corresponding records in the Attributes table.  In addition, the particular pesticide applications that occurred in 1995 in the selected watershed(s) will appear highlighted in yellow in the pstuse95.txt table.

More importantly, the highlighted records in the chemcomp.txt table will show you which pesticides were applied in the watershed and what chemicals those pesticides contained.  You can now alphabetize the pesticides by clicking on the column heading for the field "Product_na" (so it turns dark gray, indicating it is the active field) and clicking the "Sort Ascending" button (third from the right on the upper set of buttons when the table window is active).  Then to get all your highlighted records to the top of the table, click on the "Promote" button (just to the right of the query button that looks like a hammer and questionmark).

Similarly, to get an alphabetical listing of all the chemicals within the pesticides used in your watershed, make the "Chemname" field in the chemcomp.txt table active by clicking on its column heading, sorting alphabetically using the sort button, and then promoting the highlighted records to the top of the table.  There's your list of the chemicals applied in your watershed(s) (at least those reported to DPR for 1995).

As a bonus, the uses.txt table shows you the types of crops or uses the pesticides were applied to in your watershed(s) in 1995.