The only members of the house to be mentioned are Lord Roote and Lucas Roote, squire to Ser Andrey Charlton who was killed by Lannister forces with the knight he served. Harroway is the shortened name for Lord Harroway’s Town, which lies on the Trident a little ways upriver from the ruby ford. It is a small town, with the lord’s apparently making their seat in a roundtower, but the ferry there (seeming to date from the time of a King Andahar) is the only way across the Trident at that point.
Information about House Roote that reveals spoilers from the books.