Cohoangler,

Mud Mountain is a single purpose flood control dam, construction completed in 1948. The reservoir is kept empty almost all the time, so there is lots of flood control space in it. It provides flood control benefits to part of Sumner, City of Pacific, and especially the Port of Tacoma. Whether the costs of maintaining and operating the project (high) are worth the benefits depends on who you ask. Pretty typicial; it's always worth it to those who benefit but do not pay the costs.

Sg