Fifteen single-stage anaerobic lagoons representing four types of swine production farms (farrow-to-feeder,crossing, farrow-to-finish, and finish) were monitored during two years to evaluate performance. Lagoon liquid andsludge were characterized for all sites. Lagoon loading rates, percent of lagoon volume occupied by sludge, sludgeaccumulation and age of lagoon at the time of evaluation were determined. The mean annual lagoon liquid Total KjeldahlNitrogen (TKN) increased with increase in average daily live animal weight per cubic meter (LAW/m3) of lagoon volume,and the rate of increase depended upon the type of production farm. The monthly supernatant TKN concentration variedas much as 50% over two years for the same lagoon, generally showing a cyclic pattern with highest concentration inmid-summer. Of the nutrient mass contained in the lagoon, about 30% of TKN and more than 90% of Total Phosphorus(Total-P) and volatile solids (VS) were contained in the sludge. The accumulation of TKN and Total-P in the sludgeincreased linearly with time. Sludge accumulation was found to be impacted both by age of lagoon and loading rate.Based on total sludge accumulated and the age of lagoon, it was determined that sludge accumulated at an approximaterate of 0.003 m3/yr per kg of LAW. This is higher accumulation rate than reported from a study in Missouri, but lowerthan reported by a study in South Carolina. It is approximately 25% of the value predicted by ASAE Engineering PracticeEP 403.2 and ASAE DATA D384.1. Additional data is needed on sludge accumulation rates in swine lagoons andcharacterization of sludge, especially considering likely changes in swine nutrition to improve nutrient utilization andreduce nitrogen and phosphorus excretion.