Regular engineering inspections of the disused Brindley tunnel ceased in the 1960s. Since then, no further exploration of the interior has been made beyond any significant distance from the north or south portals. Both entrances are gated and are no longer reachable by boat. Water entering the canal from the Brindley tunnel has been blamed for much of the prominent iron ore leaching into the canal (responsible for the rusty colour of the water). Installation of reed beds at the northern portal to filter the water has been proposed.