City engineering and planning staff told the Preston City Council that recent water modeling shows the city's potable water supply could approach or exceed reliable capacity if recent "will‑serve" commitments and proposed development are all built out. Keller Associates advised the city to begin requiring developers to supplement municipal culinary water supply, and council backed staff's decision to notify applicants immediately.

Sean Alverson summarized the situation: models for a proposed subdivision showed the city's maximum daily demand would "approach the city's reliable water well capacity" if current will‑serve agreements were counted. Keller Associates recommended the city "begin discussions to supplement the existing municipal water supply capacity." The council then discussed the city code (section 16.10.010) that allows additional water rights or shares to be required for subdivisions.

City engineer and staff explained how the approach would typically work: developers of larger subdivisions could be required to provide water rights or shares (or a new well) commensurate with the development's demand; for smaller subdivisions the city could require a proportionate transfer of water rights that the city would bank for future system improvements.

Council voted to support the memorandum instructing staff to inform any new subdivision applicants that additional culinary water sources, water rights or shares may be required as a condition of approval. Council members and staff clarified that the current code language applies to subdivisions and that staff will bring code updates later to make the requirement clearer and potentially expand it to PUDs and other development types.

City staff said the policy change is effective for new applications going forward; it does not retroactively affect projects already in process. The council asked staff and the city attorney to prepare code language and to ensure that any new requirements are applied consistently and legally.