Achievement of management goals for Lake Champlain (Vermont/New York, USA and Quebec, Canada) will require reduction of agricultural phosphorus loads, the dominant nonpoint source in the Basin. Cost-effective phosphorus reduction strategies need reliable treatment techniques beyond basic cropland and waste management practices. The Lake Champlain Basin Agricultural Watersheds National Monitoring Program (NMP) Project evaluates the effectiveness of livestock exclusion, streambank protection, and riparian restoration practices in reducing concentrations and loads of nutrients, sediment, and bacteria in surface waters. Treatment and control watersheds in northwestern Vermont have been monitored since 1994 according to a paired-watershed design. Monitoring consists of continuous stream discharge recording, flow-proportional sampling for total P, total Kjeldahl N, and total suspended solids, grab sampling for indicator bacterial, and land use/agricultural monitoring. Strong statistical calibration between the control and treatment watersheds has been achieved. Installation of riparian fencing, protected stream crossings, and streambank bioengineering was completed in 1997. Early post-treatment data suggest significant reduction in P concentrations and loads and in bacteria counts in the treated watershed. Monitoring is scheduled to continue through 2000.