Artificially constructed wetlands offer a low cost treatment alternative to remove a number of pollutants found in effluent water from industry, mining, agriculture, and urban areas. Wetlands can be used to mechanically remove suspended solids through sedimentation. Dissolved nutrients, biochemical oxygen demand (BOD), heavy metals, and potentially harmful anthropogenic compounds can all be removed in constructed wetlands through geochemical and biological processes. Treatment efficacy is directly related to hydraulic characteristics and retention time within the wetland. Therefore, internal monitoring is important for adaptive management as well as development of future design criteria. Sample collection to evaluate the effectiveness of treatment and to monitor the status of wetlands is usually only conducted at the inlet and outlet of the wetland due to cost constraints. To better understand the internal hydrology and biogeochemical processes operating within constructed wetlands more intensive sampling is needed that does not interfere with the hydraulics of the system. A new relatively low cost sample collection design has been developed using mostly off-the-shelf parts that allows for permanent, internal, three dimensional sample collection in wetlands. The design has been used to construct a permanent 3-dimensional array of 60-sample locations that can be sampled simultaneously from a 1.2 ha constructed wetland for less than $5000 (US). The sampling array was used to characterize the internal hydraulics of the wetland and provided evidence of short-circuiting through the wetland as well as vertical stratification.