Our landscape design on a major university campus utilizes exclusively native and adapted plantings. The university does not use permanent irrigation systems for the bulk of its campus landscapes. Accordingly, the project will incorporate a temporary system designed to support the needs of plantings during the initial establishment period. Aware that the USGBC allows temporary irrigation systems to operate for one year only, the maintenance staff have expressed serious concerns that this will not allow enough time for adequate plant establishment. It has been their experience that the soil, weather and seasonal extremes in this location require a minimum 2-year establishment period. The facility manager has used 1 year temporary systems in the past which led to the death of large plant material quantities and the loss of substantial economic resources. Upon reviewing previous CIRs, the design team noticed another project description which mentioned the use of temporary irrigation systems for a 2 year duration (see CIR for WEc1.2 dated 08.29.2005). In light of the direct experience of the maintenance staff, the language used in the ruling of the CIR mentioned above, and in the interests of conserving material and economic resources, the design team would like to attempt to satisfy WEc1.2 with a two year, temporary system. The design team would like to install the most cost-effective, environmentally sound and resource conservative irrigation system possible for the duration of the proposed 2 year plant establishment period. As such, we see significant economic and environmental disadvantages to using drip irrigation exclusively. Drip irrigation systems apply water to plant material more efficiently than spray heads and impacts but require more investment in labor and plastic tubing that will ultimately end up in a landfill. The proposed system will be a combination of impact heads and drip tubing where they are appropriate for the landscape type, surrounding site programming and character of the landscape aesthetic. While this practice will conserve more water than a traditional system because its short term use, it is unlikely to achieve 50% water use reduction compared to a baseline case. To clarify, are the temporary irrigation system allowed by credit WE1.2 subject to the 50% reduction in irrigation water use specified in WEc1.1? In addition, while it may be implied, we can find no place in the reference manual where it explicitly states that a temporary system can be run using potable water. Is this allowed?