Except as provided in WAC 222-30-110, unit size and timing of timber harvesting by even-aged harvest methods is subject to the following requirements:

(1) Timber harvest which would result in an area larger than one hundred twenty acres and smaller than or equal to two hundred forty acres harvested by even-aged harvest methods on land owned or controlled by one landowner shall be reviewed by an interdisciplinary team, if the department determines that review is necessary. The area harvested by even-aged harvest methods, for the purposes of this subsection, shall be determined in accordance with subsection (3) of this section.

(2) Timber harvest which would result in an area larger than two hundred forty acres harvested by even-aged harvest methods on land owned or controlled by one landowner shall be prohibited. The area harvested by even-aged harvest method for the purposes of this subsection shall be determined in accordance with subsection (3) of this section.

(3) In calculating areas harvested by even-aged harvest methods, the area harvested by even-aged harvest methods shall include the acreage of that harvest unit and, all contiguous acreage harvested by even-aged harvest methods which is owned or controlled by the same landowner, except that acreage harvested by even-aged harvest methods sharing 10% or less of the common perimeter with the harvest unit under consideration shall not be considered contiguous for the purposes of this section.

(4) Harvest units shall be designed so that each harvest unit meets at least one of the following criteria:

(a) At least thirty percent of the unit's perimeter is in stands of trees that are thirty years of age or older;

(b) At least sixty percent of the unit's perimeter is in stands of trees that are fifteen years of age or older; or

(c) At least ninety percent of the unit's perimeter is in stands of trees that have survived on site a minimum of five growing seasons or, if not, have reached an average height of four feet.

Evaluation of unit perimeters is subject to the conditions specified in subsection (6) of this section.

(5) The requirements of subsections (2), (3), and (4) of this section shall apply only to timber harvest by even-aged harvest methods and shall not apply to timber harvest to salvage timber damaged by wind, disease, insects, fire, or other natural causes or to forest practices involving the clearing of land of brush or understocked hardwoods to convert to managed hardwoods or conifers.

(6) In evaluating the perimeters of harvest units pursuant to subsection (4) of this section, the following conditions shall apply:

(a) The following shall be treated as fully stocked, mature stands that will not be counted as contiguous acreage harvested by even-aged methods for the purposes of subsections (1) and (2) of this section and which will be counted as thirty-year-old stands for the purposes of subsection (4) of this section:

(i) In Western Washington, a wetland management zone that is twice the width required by WAC 222-30-021 and 222-30-023(1) along Type S or F Waters;

(ii) In Eastern Washington, wetland management zone that is the width required by WAC 222-30-022 and 222-30-023(2);

(iii) Designated upland management areas;

(iv) Lands in a shoreline of statewide significance where harvest is limited under RCW 90.58.150;

(v) The portions of a perimeter consisting of land in uses other than forest land, such as land in agricultural or residential use and natural openings, and land not owned or controlled by the landowner who has proposed the harvest unit subject to the application under consideration;

*(vi) Along Type S and F Waters, a continuous buffer meeting the requirements of WAC 222-30-021 and 222-30-022;

*(vii) Along Type Np Waters, a continuous 50-foot wide no-harvest, no-salvage buffer.

(b) A stand of trees other than those described in (a) of this subsection shall be treated as a certain age class only if the stand is at least three hundred feet wide;

(c) Timber harvest units subject to an approved application or a notification for timber harvesting shall be treated as if the timber harvesting operation proposed in the application or notification were completed and regeneration not yet established.