Tigers bounced back from their home nilling by Wigan Warriors five days earlier with a crucial success which keeps them firmly in the running for a place in the Betfred Super League play-offs.
Cas led three times in the first half and were four points clear at the break, but had to survive heavy pressure at times in the second period before Peter Mata’utia’s late try took the game out of Salford’s reach.
Powell said: “We didn’t have our recognised half-backs and Pete [Mata’utia] and JT [Jordan Turner] stood in and did a great job I thought, but you’re never going to be as fluent without players who play there consistently.
“I thought our discipline was a bit off in the first half, which allowed Salford a lot of field position and it was a to and fro’ game we couldn’t really get on top in.
“I thought it was pretty even in the first half, but in the second half I thought we were great.
“We defended our tryline really well and were better in good attacking positions.
“Both half-backs scored running the ball, which is a key strength of theirs and it was a big win for us.”
Hooker Paul McShane scored Tigers’ first try and set up their second on his return from an abdominal injury, but an ankle problem kept him off the field after the break.
“Losing Paul at half-time put us under pressure, but Adam Milner stepped in and I thought he had a really good second half,” Powell said.
McShane is set to undergo a scan early next week.