Municipal water law

What is a municipal water right?

The MWL defines beneficial uses of water that are for municipal water supply purposes. This typically involves serving 15 or more residential service connections or 25 people or more for at least 60 days a year. A water right holder may also apply to change the purpose of use of a water right to municipal water supply purposes.

The municipal water law

The usual process for obtaining a new water right includes submitting an application, being granted a permit, using water as specified in the permit (“perfecting” the water), and then being issued a certificate based on actual beneficial use. However, prior to the MWL Ecology issued some water rights in error based on the physical infrastructure of a utility or municipal supplier (called “pumps and pipes certificates”) rather than beneficial use.

The Legislature passed the MWL in 2003, in part to help address the question of if these were legal rights since they were not based on beneficial use. The MWL provides certainty that these “pumps and pipes” certificates are legal water rights.

Relinquishment  

Generally, a water right may be wholly or partially relinquished through extended periods of non-use. However, the MWL protects municipal rights from being revoked or diminished by Ecology, except during the change application process. This protection from relinquishment allows municipal suppliers the flexibility to access the inchoate (never used) portions of water rights that were issued to them to serve their future growth.

Tentative determinations

We need to conduct a tentative determination of extent and validity of a municipal water right when there is a change application. In this evaluation, Ecology determines how much of the water right is valid and eligible for change to prevent impairment of other rights. It is also one situation where the MWL specifically states that municipal water rights can be revoked or diminished.

To learn more about some of the factors we consider for tentative determinations, including considerations from case law, read the Focus On: Ecology’s Approach to Municipal Water Right Transfers.

If you have questions about your municipal water right, come talk to us.

Court rulings

Like many areas of water law, MWL implementation is shaped by court rulings. These decisions guide how we interpret certain parts of the law. Some of the influential cases that have shaped the implementation of the MWL include:  

• Theodoratus (1998)
• Lummi Indian Nation (2010)
• Cornelius (2015)
• Crown West (2019)

To read more about how we interpret the MWL and subsequent case law, read our POL-2030: Municipal Water Law Policy and Interpretive Statement.

Water system planning

Under the MWL, both Ecology and DOH have a role in reviewing planning and engineering documents submitted by water systems (such as water system plans). Our main responsibilities in this joint review process are:

• To evaluate if water systems have adequate water rights to supply their current and projected future needs.  
• To determine consistency with a watershed plan adopted in the local basin.

DOH is responsible for review of other aspects of these documents and for making the final decision on document approval.

To read more about how Ecology and DOH coordinate their review, read the Memorandum of Understanding that describes the roles for each agency in this process. Also, see the Joint Review Procedures for more details on the coordinated review process.