16 May 2018 Jan’s latest Tenerife News is much better than our original report:-
Hi David & Ros, fresh updates: 
Just talked to cabildo and boat companies in Los Gigantes. 
GR131 between Deg.de Guajara and Vilaflor has just reopened (since yesterday). 
Paisaje Lunar (PR-72) remains closed. No estimation of when it could reopen. 
Bco de Masca - repairs underway, current estimation is that the ravine could be reopened within one to one and half month. 

All the best, Jan
That’s much better than our original report a week earlier
1st report 8 May 2018 Latest news on official walking routes is not good for the short term future.
Paisaje Lunar currently closed due to recent forest fires in the area, even the GR131 to Vilaflor is closed. This affects the routes of Walks 30 & 34 in Walk! Tenerife.
We think this is a temporary closure for the fire damage to be cleared on the official routes. Hopefully routes in this region will reopen before the Autumn walking season opens. Jan Kostura will be looking at the situation when he is on Tenerife in the next month.
Barranco de Masca (Walk 26) - closed since approx March. After the rainy period turned Masca into a river, (there are some interesting videos) there was prohibited access to the ravine, broken by bunch of tourists who got trapped there and needed to be rescued. Perhaps this rescue action was a last drop and now the ravine may possibly be closed indefinitely!
Since that news Jan has been in touch with the boat operators who think the ravine will reopen in a ‘few weeks’ by one and ‘the Autumn’ by another.
Jan’s local contacts have heard rumours that the island government will turn it into another "Barranco del Infierno", so with access based on internet permit, limited permits, with paid access... Nothing is for sure, it is all rumours for now, but already in the last years we could see that the traffic there is on its limits and with the volume of tourists, some not respecting the rules, something was going to change... 
Jan will be updating us as soon as he has assessed the situation on the ground and spoken to his official contacts and local hiking friends.