Payment or Collection of Fees. Each of the Permittees shall pay or collect mitigation fees as required pursuant to the applicable sections of the SLCHCP. Under the SLCHCP, a two-tier impact fee assessment system for desert tortoise will be implemented over the 30-year permit within the Covered Area. A fee of $550/acre will apply to development occurring south of the northern-most location of critical habitat for desert tortoise within the Covered Area of the SLCHCP, and a fee of $250/acre will apply to development occurring north of the northern-most location of desert tortoise critical habitat within the Covered Area; with the exception of UPRR who will pay $550/acre throughout the Covered Area. For southwestern willow flycatcher, the responsible Party will pay $12,000 per acre for loss of suitable flycatcher habitat. The mitigation fee of $12,000 per acre for loss of suitable flycatcher habitat was derived from known costs of other riparian restoration projects occurring within the western and southwestern United States (refer to Section 6.7.2.2.1 in the SLCHCP). The amount of these fees shall not change during the term of the SLCHCP, the Permit and this Agreement. Where mitigation fees are required to be paid pursuant to the SLCHCP and this agreement, no party shall be required to pay such fees for land disturbance in previously disturbed habitat as defined in Section 6.3.2.1 of the SLCHCP.