1.  conservancy(n = noun.group) - a commission with jurisdiction over fisheries and navigation in a port or river;
is a kind of commission, committee

2.  conservancy(n = noun.act) - the official conservation of trees and soil and rivers etc.;
is a kind of conservation

   Conservation, as from injury, defilement, or irregular use. [1913 Webster]
"[An act was] passed in 1866, for vesting in the Conservators of the River Thames the conservancy of the Thames and Isis." [1913 Webster]

conservancy, n. (pl. -ies)
1 Brit. a commission etc. controlling a port, river, etc. (Thames Conservancy).
2 a body concerned with the preservation of natural resources (Nature Conservancy).
3 conservation; official preservation (of forests etc.).

Etymology:
18th-c. alt. of obs. conservacy f. AF conservacie f. AL conservatia f. L conservatio (as conserve)