The department shall divide the State into watermaster service areas so constituted and adjusted as to insure the most practical and economical supervision of the distribution of water on the part of the State.

Service areas shall be created from time to time as rights to water are ascertained and determined.

The rights may be ascertained and determined by any or all of the following:

When rights are ascertained and determined by agreement, the agreement shall be recorded in the office of the county recorder of each county in which is situated any water rights involved, and in the office of the county recorder of each county in which is situated the land, or any portion thereof, on which any water involved is, or is entitled to be, used.

When rights are ascertained and determined by court decree, certified copies of the decree shall be recorded as agreements are required to be recorded by Section 4028.

Upon the creation of a service area the department shall record in the office of the county recorder of each county in which a portion of the service area is situated a certified copy of the order creating the service area and a description by 40-acre subdivision or other smallest subdivisions of the public land surveys of all of the land within the service area which is within the county in which the description is recorded.

From time to time the department shall record supplemental or revised descriptions as the descriptions are changed.

Service areas may be enlarged, reduced, consolidated, or abolished from time to time as convenience of administration may require.