Physical and biological standards are identified in the SONGS coastal development permit that specify how the wetland and reef mitigation projects should perform to be considered successful, and the timing and level of monitoring that is needed to evaluate their performance.
Two general types of physical and biological performance standards are being used to judge the success of the wetland and reef mitigation projects: (1) absolute standards that are measured against criteria set in the SONGS Permit, and (2) relative standards that require certain features of the mitigation projects to be similar to natural reference sites that are removed from the adverse impacts of SONGS.
Evaluating compliance with the relative performance standards requires the use of an objective approach to determine whether the values of the performance variables at the mitigation sites are similar to those at the reference sites. The elements considered in developing the method for assessing similarity between the mitigation and reference sites include:
- The amount of difference between the mitigation site and the reference sites that can be detected (i.e. effect size),
- The amount of error associated with concluding that the mitigation site and the reference sites are different when in fact they are similar (i.e., Type I error),
- The amount of error associated with concluding that the mitigation site and the reference sites are similar when in fact they are different (i.e., Type II error), and
- Sample size, which not only affects the cost of monitoring, but also the level of certainty in the estimated performance values for the mitigation sites and reference sites (and hence the effect size, and Type I and Type II errors).
The methods for determining similarity are detailed in the monitoring plans for the wetland and artificial reef.