We examine a landowner’s problem of deciding on streamside management zone (SMZ) width under common regulatory constraints concerning water protection standards, assuming there is a prototypical landscape consisting of a productive planted forest and a stream buffer area of fixed starting width. We characterize an optimal width of these riparian buffer forests, and we determine how this decision depends on features such as expected erosion value, SMZ slope, and soil type. We also examine the intensity at which a landowner chooses to harvest within the SMZ, assuming they have the option to do so. The jointness of the decision on SMZ width and its harvesting intensity with other decisions such as rotation ages of the productive forest is analyzed theoretically and through a simulation for a prototypical pine forest in Virginia, United States. We show how several landscape and decision factors may influence SMZ decisions while still allowing the landowner to maximize land value. Given an acceptable rate of sediment delivery to the stream and tax incentives to set aside land as a buffer area, we find that (1) higher SMZ slopes, finer soil texture and higher harvest rates within the SMZ in general lead to a wider buffer area; (2) the impact of harvest intensity on sediment retention may change the optimal SMZ width, productive forest rotation age, and SMZ harvest intensity combination. We also find that not harvesting within the SMZ (even when allowed) might be optimal in the presence of a tax incentive depending on the effects of harvest intensity on soil retention and despite the value of timber in the buffer forest. Our model and results can be used to inform future policy aimed at reducing sediment runoff from harvesting operations into water bodies while simultaneously improving land value for the landowner and promoting sustainable water resource management.