See also Overview of the Data Preparation Process and Assemble Parcel Data for general description of process and documentation of specific scripts and procedures used in this step.
Initial parcel data for all four central Puget Sound counties was provided by the PSRC. The goal of the process was to create a 2000 base year flat parcel table for the central Puget Sound. For some counties, additional data needed to be obtained to complete the flat parcel attribute table. Due to time lags in updating parcel files, and some systematic gaps in the Snohomish County parcel file that existed in the 2000 database, GIS coverages of parcel boundaries for the year 2001 were collected and processed. Attributes of parcels were assembled from county tax assessor files for each county, and these were supplemented with information from buildable lands analyses in Pierce and Snohomish Counties. For all four counties, the area of the parcel was obtained from the GIS area measurement for the parcel.
A look-up table was created to categorize the various county land use codes into standardized and more general land use categories. The look-up table created two levels of land use category aggregation. GENERIC_LAND_USE_1 aggregated land use codes into 26 categories and GENERIC_LAND_USE_2 aggregated land use codes into six broader categories (commercial, government, industrial, residential, non-residential, and group quarters). GENERIC_LAND_USE_1 is utilized later in the job allocation process and to help analyze data quality indicators. GENERIC_LAND_USE_2 is used later in Step 7 and Step 8 when parcel data is assigned to gridcells. The look up table is available here: Look-up table for land use reclassification and building use reclassification
County parcel addresses often follow different naming conventions and need to be standardized. A SAS script was used to parse parcel address fields into five separate fields: street number (st_no), directional prefix (st_pf), street name (st_name), street type (st_type), and directional suffix (st_sf). An example of the SAS script used to parse Pierce County, Washington addresses is available here: SAS script for address parsing
The county assessor's records contained supplemental tables identifying tax exempt parcels. The tax exempt coding system was relatively consistent throughout all four counties with the exception of Pierce County. Pierce County contained a unique code system that required a look up table in order to determine whether a parcel was tax exempt.
A King County extract table (EXTR_RpAcct.csv) was used to update the tax exempt field in the flat parcel files. According to the outline of the King County extract table the "TaxStat" field denotes whether a parcel is taxable: T = Taxable, X = Exempt, and O = Operational.
The Kitsap County tax exempt field was updated using a combination of supplemental tables provided by the Assessor's Office. These tables contained information for all real property in Kitsap County (Bainbridge Island, Bremerton, Central Kitsap, North Kitsap, South Kitsap, and a portion of North Mason School District within Kitsap County). The "STATUS" field in the supplemental tables distinguishes taxable parcels.
The Pierce County tax exempt field was given in the Master Assessor's file "Exmpt_cd". However, this field contained an assortment of values ranging from 1-9 and A-W that needed a tax exemption look up table. We received the look up table from the Assessor's Office which linked between the before mentioned values and a description for each of the values with the exception of values A, B, and C.
A supplemental table was used to update the Snohomish County tax exempt field in the parcels table. The table (Tbl-RptXtr01-Exemptions.txt) contained only records of parcels that are tax exempt.
The parcel data assembly and standardization process for each county is described below in greater detail.
A 2001 parcel shape file and tax assessor's file for King County was provided by the PSRC. The coverage only contained a Parcel Identification Number (PIN) and land use code. A total of 12 additional tax assessor file extracts from King County were obtained through the Washington Geospatial Data Archive (WAGDA) for the following tables: apartment complex extract, condominium complex extract, residential buildings extract, parcel extract, real property account extract. Assessed land and improvement values were summed by PIN number to aggregate across building records for each parcel, and these were linked to the parcel shape file by PIN.
A 2001 parcel shapefile and tax assessor's file for Kitsap County was provided by the PSRC. The assessor's data and parcel shapefile matched up very well and very little additional work was needed to join the data sets by PIN. Residential units data was taken from the Kitsap County's LANDCODE table, which was linked to the assessor's table on the Real Property Account (RP_ACCT) field.
A 2001 parcel shapefile and attribute file from Metroscan for Pierce County was provided by the PSRC. The attribute file had several problems: the housing units, square footage, and year built fields appeared to be corrupted and had unusable data, and the file did not include assessed land and improvement values. In order to generate usable data, the 2003 assessor's file was substituted for the 2001 file, and the attributes appeared to be reasonably complete in this file, but represented more recent conditions than the desired base year 2000. In order to better reflect the 2000 baseyear, additional data sources were sought out. Three buildable lands coverages with 2000 parcel data were provided by Pierce County via the PSRC. One coverage was for the City of Tacoma, one was for several incorporated jurisdictions and one was for several unincorporated areas. The buildable lands data sets included fields for improvement value, land value, and land use. The county coverage file was updated with values from the buildable lands data sets so that the parcel data would better reflect 2000 totals. The assessor's data was linked to the parcel coverage by PIN.
A 2001 parcel shapefile and tax assessor's file for Snohomish County was provided by the county. The tax assessor's file appeared to have problems with the land use code and the number of housing units (for example, apartment housing units were not recorded, and duplexes frequently only recorded 1 unit), based on analysis of the data and interaction with county staff. Multiple shape files for year 2000 buildable lands analysis were obtained from the PSRC and used to update housing units, land use, land value and improvement value in the tax assessor's file.