(1) Introduction. The acceptable log scaling and grading standard for stumpage value areas 1, 2, 3, 4, 5, and 9 is the Scribner Decimal C log rule as described in the most current edition of the "Official Log Scaling and Grading Rules" developed and authored by the Northwest Log Rules Advisory Group. The acceptable log scaling standard for stumpage value areas 6 and 7 is the Scribner Decimal C log rule described in the most current edition of the "Eastside Log Scaling Handbook" as published by the Northwest Log Rules Advisory Group, except that timber harvested in stumpage value areas 6 and 7 must be scaled using the current regional taper rules at the point of origin.

(2) Special services scaling. Special services scaling as described in the "Official Log Scaling and Grading Rules" developed and authored by the Northwest Log Rules Advisory Group may not be used for tax reporting purposes without prior written approval of the department of revenue.

(3) Sample scaling. Sample scaling may not be used for tax reporting purposes without prior written approval of the department of revenue. To be approved, sample scaling must be in accordance with the following guidelines:

(a) Sample selection, scaling, and grading must be conducted on a continuous basis as the unit is harvested.

(b) The sample must be taken in such a manner to assure random, unbiased sample selection in accordance with accepted statistical tests of sampling.

(c) The sample used to determine total volume, species, and quality of timber harvested for a given reporting period must have been taken during that period.

(d) Sample frequency must be large enough to meet board foot variation accuracy limits of plus or minus two and five-tenths percent standard error at the ninety-five percent confidence level.

(e) Harvesters, or a purchaser with an approved sample scaling method, must maintain sufficient supporting documentation to allow the department of revenue to verify source data, and test statistical reliability of sample scale systems.

(f) Exceptions: Sampling designs and accuracy standards other than those described herein may only be used with the prior written approval of the department of revenue.

(4) Conversions to Scribner Decimal C Scale. The following definitions, tables, and conversion factors must be used in determining taxable volume for timber harvested that was not originally scaled by the Scribner Decimal C Log Rule. Conversion methods other than those listed are not to be used for tax reporting purposes without prior written approval of the department of revenue. Harvesters who wish to use a method of conversion other than those listed below must obtain written approval from the department of revenue before harvesting. Purchasers may obtain written approval of a sample scaling method from the department of revenue. The department will maintain a list of purchasers with an approved sample scaling method. A harvester may obtain this list and a summary of the approved method for specific purchasers from the department of revenue. If a harvester has not obtained approval of a sample scaling method before harvesting, the harvester may use a purchaser's approved sample scaling method. If the harvester, or purchaser, fails to use an approved sample scaling method or other method of conversion approved by these rules to set the purchase price, the department will establish its own method, as the circumstances require, to determine a reasonable estimate of the volume of timber sold.

(a) Weight measurement. If the sole unit of measure used to set the purchase price for logs from harvest units was weight, and the harvester does not use an approved method of sample scaling to determine volume for the stumpage value tables, the following tables must be used for converting to Scribner Decimal C, if the harvest volume per species meets the definition listed in the table. If weight is the sole measure used for a harvest unit and the harvest volume per species does not meet the definition listed in the table below, the department will establish its own method, as the circumstances require, to determine a reasonable estimate of the volume of timber sold. Harvesters must keep records to substantiate the species and quality codes reported. For tax reporting purposes, a ton equals 2,000 pounds.

(b) Cord measurement. For the purposes of converting cords into Scribner volume:

(i) In stumpage value areas 1, 2, 3, 4, 5, and 9 logs with an average scaling diameter of 8 inches and larger must be converted to Scribner volume using 400 board feet per cord. Logs having an average scaling diameter of less than 8 inches must be converted to Scribner volume using 330 board feet per cord.

(ii) In stumpage value areas 6 and 7 logs with an average scaling diameter of 8 inches and larger must be converted to Scribner volume using 470 board feet per cord. Logs having an average scaling diameter of less than 8 inches must be converted to Scribner volume using 390 board feet per cord.

(iii) A cord of Western Redcedar shake or shingle blocks must be converted to Scribner volume using 600 board feet per cord.

(iv) Firewood must be converted at a rate of 3 tons per cord.

(c) Cants or lumber from portable mills. To convert from lumber tally to Scribner volume:

(i) In stumpage value areas 1, 2, 3, 4, 5, and 9 multiply the lumber tally for the individual species by 75%, and round to the nearest one thousand board feet (MBF); or

(ii) In stumpage value areas 6 and 7 multiply the lumber tally for the individual species by 88%, and round to the nearest one thousand board feet (MBF).

(d) Log scale conversion. Timber harvested in stumpage value areas 1, 2, 3, 4, 5, and 9 and which has been scaled by methods and procedures published in the "Eastside Log Scaling Handbook" must have the volumes reported reduced by eighteen percent. Timber harvested in stumpage value areas 6 and 7 and which has been scaled by methods and procedures published in the "Official Log Scaling and Grading Rules" developed and authored by the Northwest log rules advisory group, must have the volumes reported increased by eighteen percent.

(e) Timber pole and piling volume tables. Harvesters of poles must use the following tables to determine the Scribner board foot volume for each pole length and class: