Leaching of nitrogen (N) following forest fertilization can negatively impact water quality through the process of eutrophication.  The purpose of this study was to quantify the amount of N that leached beyond the rooting zone of N-limited Douglas-fir (Pseudotsuga menziesii) forests the year following urea fertilization and determine the potential impact of this on the water quality of Hood Canal, WA.  At six sites on production forests in the Hood Canal watershed, tension lysimeters were used to quantify the mobilization and loss of NO₃–N, NH₄–N, and dissolved organic nitrogen (DON).  Soil samples and overstory and understory vegetation were collected before and after fertilization to calculate changes in N pools.  In the year following fertilization, the total leaching loss from the primary rooting zone was 4.2 kg N ha^-1 (p = 0.03) which is equal to 2% of the total N applied.   The peak NO₃–N concentration that leached beyond the rooting zone of fertilized plots was 0.2 mg NO₃–N L^-1 which is well below the level found to damage human health (10 mg NO₃–N L^-1; US EPA, 1986).  Six months post-fertilization, 26% of the applied N was accounted for in the overstory and 27% was accounted for in the O+A horizon of the soil.  Using estimates of anthropogenic N loads to Hood Canal (Fagergren et al., 2004), a worst case calculation of the potential impact forest fertilization has on water quality suggested that leached fertilizer N could account for 0.9-3.5% of the total anthropogenic N load.