I have read the varying Forum posts on Cambokeels plus the history of the mine and find that the details posted vary from my firsthand knowledge.
Perhaps someone can put me right.
It is stated here that the mines closed in the 1980s.
During frequent visits to the Durham Dales, I noted that both Cambokeels and the Frazer-Grove Complex (Frazers Hush & Grove Rake) were being operated in the late 1980s by the Minworth Group, a company known for the mining and supply of Barytes to the North Sea oil drilling business.
The Minworth Group went into administration in, I think, 1991 and all mining stopped, though the pumps were left running. In the mid 1990s Sherburn Stone took over the mining rights. Sherburn stone is a quarrying company and this was their first attempt at mining. They appear to only have worked Grove Rake, cannibalising equipment from Stanhopeburn and Cambokeels to keep Grove Rake open. They only lasted a few years and when they abandoned Grove Rake, all pumps were switched off and the workings allowed to flood, causing some local discussion over mine water contamination of local streams.
Durham County Council had some mine water settling ponds built near Rookhope with water from Cambokeels and Grove Rake being piped to the ponds. They caused an uproar, because the settling ponds destroyed a line of Grade 2 listed bell pits, with the excuse that the warning letter "Got onto the wrong desk". No further action was taken.
Can someone please correct me if I am wrong in any respect.?

Think you are correct on the Minworth Group involvement at Cambo. IIRC Cambo finally closed in September 1989 and was canabalised by Sherburn Minerals to keep Frazers going.

Mining in the deep sections of Frazer’s Hush by Sherburn Minerals was stopped at the end of 1998. The dewatering pumps were switched off and removed from the No2 Shaft, on March 5th 1999, at which point the groundwater started to rise. Mining of the shallower workings in the Rake Level/Firestone Incline workings continued until July of 1999 when the mining operations at the last Weardale mine finally ceased.

As discussed previously on here "The old smelt mill at Rookhope was seriously damaged in 2000 by an emergency operation to contain polluted minewater from the Tailrace Level of the recently closed Frazer's Complex just upstream.

According to press reports, the Environment Agency, in their haste, failed to check their own lists of protected ancient monuments before constructing lagoons to contain the minewater which was about to come out of the Tailrace Level into Rookhope Burn. Apparently the agency had failed to consult the county archaeologist and had not responded to his telephoned attempts to intervene. Sadly 60% of the site was destroyed.

A full dig was later carried out to see what could be saved and the Agency agreed to continue work at the site from mid-February under the supervision of an archaeologist." Would be nice to find a reference for this, I had a Google with poor results!

No water from Cambo was piped to Rookhope, there is a reed bed filtration system on site adjacent to the River Wear (now seriously neglected!), water from the incline dib was still draining through it when I was last up there 😉

---

I was told that it was the Environment Agency that advised switching off the pumps in the first place
The theory being that minewater would take years to filter out and come out clean all by itself.

When minewater did emerge and made a huge mess the Environment Agancy took "emergency action" and destroyed the smelt mill in the process.

The destruction of the smelt mill and the bell pits was done by a friend of mine on contract to Durham County Council. He pointed out to DCC about the historic significance of the site but was told to "just do it or lose the contract!"