A total of 44 intermittent sand filter-septic systems, in five counties of Western Oregon, were sampled over a three-month period during the summer of 1995. The sand filter systems varied in age from 36 months up to 167 months (3 to 13.9 years). Liquid samples were taken from the septic tank and distribution box. In addition, soil samples were taken adjacent to the disposal trench and away from the disposal field area (control). All samples were analyzed for Total Kjeldahl Nitrogen (TKN) and nitrate and nitrite. Nitrite was not detected in any of the samples. The average removal of total nitrogen (TKN + nitrate) through the filter was found to be 43%. Nitrate was determined to be the dominant form of nitrogen in the sand filter effluent making up 94% of the total nitrogen. The age of the system was found not to be a predictor of the system's performance. Once the effluent entered the disposal field, little if any transformation of nitrogen occurred at an average depth of 30 inches (76.2 cm). / Graduation date: 1996