Manure is a valuable source of Phosphorus for crop production. However, applying too much manure P, especially in the wrong place, is not only agronomically wasteful, but potentially harmful to the environment. As a result of recent increases in Manitoba’s production of livestock, the risk of transfer of manure P from agricultural land to surface water is probably increasing. However, the amounts of P that are discharged from livestock production and other agricultural activities are very difficult to determine due to a lack of hydrological data and, more important, a lack of data on the transfer of P from soil to water. Part of this problem is due to the highly variable impact of soil type, P management, landscape and climate on P retention and release by soil, information that is not well documented for Manitoba conditions. Fortunately, livestock producers have a wide variety of potential techniques for reducing P discharge from their operations; however, the technical and economic merit of these techniques is generally not well documented either, for Manitoba conditions. As a result of these challenges, legislation and regulation regarding P management should be introduced cautiously to ensure environmental protection without undue hardship to the agricultural industry. The Manitoba Livestock Manure Management Initiative (MLMMI) initiated this project in response to concerns about increasing concentrations of phosphorus (P) in Manitoba’s surface waters. Manure P has been identified as a significant source of soil P enrichment in areas of high density of confined livestock operations. The objective of the first phase of the project was to review existing knowledge on the role and fate of P in livestock and crop production systems specifically relevant to Manitoba and to identify gaps in that knowledge. The objectives for the second phase were to: investigate the feasibility and effectiveness of several options for regulating P management in Manitoba, and conduct four case studies to evaluate the impact of various regulatory options for P management on Manitoba hog farms.