Regional cooperation among urban water utilities is a powerful mechanism
for improving supply reliability and financial stability in urban water
supply systems. Through coordinated drought mitigation and joint
infrastructure investment, urban water utilities can efficiently exploit
existing water supplies and reduce or delay the need for new supply
infrastructure. However, cooperative water management brings new
challenges for planning and implementation. Rather than accounting for
the interests of a single actor, cooperative policies must balance
potentially competing interests between cooperating partners. Structural
imbalances within a regional system can lead to conflict between
cooperating partners that destabilize otherwise robust planning
alternatives. This work contributes a new exploratory modeling centered
framework for assessing cooperative stability and mapping power
relationships in cooperative infrastructure investment and water supply
management policies. Our framework uses multi-objective optimization as
an exploratory tool to discover how cooperating partners may be
incentivized to defect from robust regional water supply partnership
opportunities and identifies how the actions of each regional partner
shape the vulnerability of its cooperating partners. Our methodology is
demonstrated on the Sedento Valley, a highly challenging regional urban
water supply benchmarking problem. Our results reveal complex regional
power relationships between the region's cooperating partners and
suggest ways to improve cooperative stability.