Excess reactive nitrogen (N_r) deposition is occurring in Rocky Mountain National Park (RMNP) and impacting its sensitive ecosystems.  To address this issue, the National Park Service, State of Colorado, and Environmental Protection Agency are collaborating through a joint Memorandum of Understanding (MOU) with the goal to reduce N_r deposition to levels below the critical load over 25 years. Progress towards this goal is tracked using five-year averages of annual wet inorganic nitrogen deposition (IN) measured at the Loch Vale NADP site.  These five year annual IN deposition rates are compared to a glidepath, which is a linear reduction from 2006 levels (3.1 kg/ha/yr) to 1.5 kg IN/ha/yr in 2032.  Loch Vale is a remote high alpine location that is challenging to operate and service particularly during large snow events in winter and spring.  When the equipment fails or operators are prevented from getting to the site within the allotted time frame, samples are invalidated by NADP.  This often leads to large fractions of the annual precipitation, at times more than 40%, to have associated invalid IN concentrations which are not used to calculate annual averages.  To calculate the annual IN deposition, NADP protocol is to replace missing samples with the precipitation-weighted annual average concentration derived from valid samples.  This process does not account for seasonal variations in the IN concentrations in addition to the inverse relationship between concentration and precipitation amounts. This can lead to large errors that can bias the annual averages, trends in these averages, and the tracking of progress towards the critical load.  In this work, we present a new method for imputing missing IN data with values that better account for the seasonal interdependence of wet deposition concentrations and precipitation depth.  In addition, a Monte Carlo analysis was conducted to evaluate various data imputation methods and the relationship between missing data and uncertainty.  Confidence intervals on the Loch Vale annual wet IN deposition rates that account for the variable fraction of invalidated data interannual variability are presented.  The influence of these uncertainties on the long-term trends of IN wet deposition at Loch Vale is also explored.