Brightwater On Hermes And Merseia

It has become impossible for me to reread a passage of Poul Anderson's History of Technic Civilization without finding something to post about, e.g., Sandra Tamarin:

"...flitted northeast from Windy Rim, across the Apollo Valley, to Brightwater in the foothills of the Thunderhead Mountains."
-Poul Anderson, Mirkheim IN Anderson, Rise Of The Terran Empire (Riverdale, NY, 2011), pp. 1-291 AT p. 184.

Notable points:

in less than a sentence, Anderson presents four place names on the colonized planet, Hermes;

these place names include "Brightwater";

we have previously noticed a Gwyanafon of Brightwater on Merseia (see also Merseians and Merseian Names) and that, on Hermes -

 The Asmundsens, Followers of the Runebergs and tenants on the Brightwater estate, manage the Runeberg's copper industry.
-copied from here. 

However, I had not noticed until now that there is a "Brightwater" on both planets. "Brightwater" is an English translation from Hermetian Anglic and Merseian Eriau.