Influence of sampling frequency and estimation method on phosphorus load uncertainty in the Western Lake Erie Basin, Ohio, USA

•Even the small decrease to semiweekly sampling produced high load estimate errors.•The composite method provided the least biased load estimates.•The interpolation method provided the most precise load estimates.•We recommended daily sampling to maintain load estimate reliability in the WLEB.•There is potential to predict load uncertainties in the WLEB.