It appears that the project was extravagant of labor, so I don't doubt that any needed maintenance would have been done by hand. It's also possible (seems likely) that the wells and tunnels were constructed after the lake bottom had dried out. That may have been accomplished by the hot sun along with so-called Archimedian Screws and other water moving techniques (such as the counterweighted buckets still used today along the Nile in Egypt). That tunnel through the rock sounds like it could antedate the wells, which would have been needed to drain off the rainwater and any spillage from the canals (since rain inland could cause them to exceed their capacity).
maybe this link? Didn't look it over.
http://www.unipg.it/%7edenz/SVIZZERA1997.pdf
from the old reliable...
Lesson 21: Mycenaean Public and Funerary Architecture:
Fortifications, Drainage Projects, Roads, and Chamber Tombs
http://projectsx.dartmouth.edu/classics/history/bronze_age/lessons/les/21.html#9