本文主旨在討論固定制度與變動環境之間的整合與衝突。透過明清時期山西河津三峪特有的水利規則「清濁分用」，觀察水規設立當下的環境與規則的關係，並評估水利規則所創造的「公平」，以及隱含在水利規則中的「不公平」現象。此外，人文社會與環境互動的過程中，固定水規所受到各種變動的衝擊。明清時期的官府都曾經重申或微調「清濁分用」的原則，但實際的社會狀況已經與明初大不相同，維持原有水利規則反而增加社會的衝突。文章最後一部分，分析一件從清初延續到民國的訴訟案件，透過實際案例說明「清濁分用」的大原則，所形成難以解決的社會問題。透過上述分析，將呈現水利規則對社會的影響，以及社會各層面的因應之道。*

This study mainly dealt with the relation between Environment(Human and Nature) Chang and Policies, by case about the rule of irrigation, called 'distinguishing water and applying apart ' (清濁分用) in Shanxi Hejin County(山西河津縣). In 1389, the rule of irrigation was set up, to solve the situation, which the upstream villages used more water for less costs, but the downstream ones reversed. When time past, Environment Chang made local government adjust the rule for reality. But that created new problem, downstream villages were working the rule of irrigat ion, manipulated their opponent, satisfied themselves, and cheated the governor. Downstream villages took advantage of upstream villages in this system, that was symbol of equity and justice.