PACR of a project (8/87-12/92) to help the Government of Sri Lanka (GOSL) to complete the tertiary irrigation system, roads, and settlements on the left bank of System B of the Mahaweli Basin, primarily Zone 4A. The project was implemented by the Mahaweli Engineering and Construction Agency (MECA), an agency under the Mahaweli Authority of Sri Lanka. Implementation was seriously curtailed by terrorist activities which resulted in the death of several MECA staff members, contractor personnel, and farmers. As a result, construction targets were cut in half in 1990 with the removal of Blocks 402, 403, and the northern part of 401 from work plans and the restriction of efforts to Blocks 404, 405, and the southern half of 401. Despite ongoing security problems, the revised targets were largely met. in all, the construction of 55 km of distributary canals, 128 km of field canals, 126 km of turnout drains, 23 km of market roads and 80 km of hamlet roads, and 1 area and 8 hamlet settlement centers (no towns or village centers were constructed), along with the clearing of 2,625 ha of jungle and 1,780 ha of on-farm development (no farm-level drainage canals were built) led to the settlement of 2,000 farmer families and 600 non-farmer families in Zone 4A. in a technical innovation, project personnel developed a revised toe drain filter design for tank embankments which reduced construction costs while improving functioning. Also, use of detailed soil information greatly facilitated the layout design and construction of irrigation project facilities, and eliminated rock outcrops and shallow soils on farm plots. a significant project achievement was a revised land use plan which deviated significantly from the conventional land use method used in the Mahaweli Agriculture and Rural Development Project. The revised plan increased homestead size from 0.2-0.4 ha to 0.5-1.0 acre and thus increased settler incomes; included high-intensity surveys, which minimized design-related construction adjustments and reduced land leveling costs; utilized down-the-slope designs for farm plots, which made the division of quality land among farmers more equitable and reduced drainage problems; and, where possible, allowed the use of operation and maintenance (O&M) roads as farm-to-market roads in order to reduce land requirements and construction costs. The project also fostered the development of farmer organizations in Zone 4A; O&M of field canals has already been transferred to these groups. Additionally, the Mahaweli Economic Agency plans to transfer O&M of distributary canals to farmer organizations. Training included in-country workshops, seminars, lectures, and on-the-job training of MECA staff (including training in computer-assisted design of tertiary irrigation systems and farm plots), and four overseas training tours for MECA engineers in investigative, design, construction, and administrative skills. Construction of the tertiary irrigation system and the settlement program in Block 401 are being continued by the GOSL. Since the PACD, some 20 km of distributary and field canals have been completed and 150 farm families settled in an accelerated resettlement program. Improvements in the main outlets of the drainage system in Zone 4A, recommended in the revised land use plan as a remedy for imperfectly drained soils, remain incomplete. Though MECA has placed a high priority on this effort, security remains a major constraint.