The style of the tower tells us that this is the newer one. This tower is located in the northeast corner of the city, while the older one is near the southwest corner, indicating that both remain in use. While the style of the older one indicates an early date of construction, research confirms that it was erected in 1909. This one, with more contemporary styling, was built in the mid 1950s. Now serving triple duty, in recent years the tower has also been recruited as a cell tower.
Not a lot of description is given on the datasheet concerning when the water tank was first observed, or anything else, for that matter.
STATION DESCRIPTION
DESIGNATION - DAVENPORT NE WATER TANK
PID - SW1138
STATE/COUNTY- WA/LINCOLN
COUNTRY - US
USGS QUAD - DAVENPORT (1992)
MARKER: 53 = ELEVATED TANK
HISTORY - Date Condition Report By
HISTORY - UNK FIRST OBSERVED
STATION DESCRIPTION
DESCRIBED UNK
RECOVERED AS DESCRIBED.
From the NGS Datasheet