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The ever-increasing popularity and traffic volume of multicast applications motivates the need for development of methodologies for traffic management and network design that especially cater for multicast traffic. Addressing the disparity between the bandwidth offered by a wavelength and the bandwidth required by a single connection is a key challenge in the efficient usage of any wavelength-division multiplexing (WDM) network. This problem is also relevant to WDM networks that support multicast traffic and can be mitigated by multicast traffic grooming. This paper considers multicast traffic grooming with a leaking strategy where a light-tree may deliver the traffic of a multicast connection to nodes that are not in the destination set of the connection. This leaking strategy improves the sharing of light-trees and add/drop ports, leading to lower blocking ratios. Two multicast traffic grooming algorithms with leaking strategy, namely, multicast traffic leaky grooming (MTLG), and multicast traffic hybrid grooming (MTHG) are proposed. MTLG grooms traffic to light-trees if the traffic leaked is less than a given threshold value. MTHG first grooms traffic to light-trees without leaking; if some destinations remain, it then grooms traffic to light-trees with leaking. MTHG is an improvement over MTLG as it can attain higher light-tree sharing with less traffic leaked. Simulations show that the two proposed algorithms perform better than other algorithms at low add/drop port ratios with MTHG showing better performance.