Vancil reservoir built in response to '64 Flood?

6 months after the '64 Flood:

The council also:
...
Accepted a bid from the Somerville Glu-Lam Manufacturers of Santa Rosa for delivery of laminated beams to roof the Vancil Street reservoir...

From: "No Increase in Taxes for City Of Fortuna"
Humboldt Beacon, Jun24, 1965, page 1


4 months before the '64 Flood:

Authorization was given Dinsmore and City Engineer John Winzler to start on the roofing project for the new city water reservoir.

From: "May Expand Rohner Park Facilities"
Humboldt Beacon, August 20, 1964, page 1

Emphasis added

Why were they building a new reservoir? Annexation was in the news.