The report identified waterborne nonpoint sources of pollution (NPSP) contributing to pollutant loadings of receiving waters within the Corpus Christi Bay National Estuary Program (CCBNEP) study area. Literature and existing data was reviewed with respect to eight categories of land use and several pollutant parameters. Land use categories include: (1) industrial/commercial; (2) transportation; (3) urban; (4) residential; (5) agricultural cropland (dryland and irrigated); (6) rangeland; (7) undeveloped/open; and (8) marinas. The first phase (Year 1) portion of the assessment of nonpoint source pollutant loadings focussed on the derivation of Even Mean Concentrations (EMCs) of various pollutants associated with each of the above eight land use categories. It is envisaged that a Year 2 CCBNEP project will model the loadings of these pollutants based on variable conditions (e.g., wet/dry year, large/small storm) for watersheds and subwatersheds within the study area. The report includes a comprehensive geographic analysis of the contribution of NPS pollutants to the CCBNEP study area and an analysis of probable causes.