4.2.10 (HL)—Governance for sustainability

Use local rules for local use, but shared rivers require cross-border authority, data and dispute procedures.

Local rules need clear triggers, essential-use protection and enforcement: in California in 2022, a regulation banned using drinkable water on decorative lawns. Shared basins require allocation rules, monitoring and dispute procedures; Cambodia, Thailand, Laos and Vietnam have cooperated on Mekong water management since 1957.

The California restriction targets discretionary local demand, while Mekong cooperation addresses cross-border flows whose upstream management affects downstream users.

The spillover crosses its authority; governance must match the hydrological boundary.

A treaty’s existence does not guarantee fair or effective implementation; inspect data, triggers and enforcement.