2012 Monitoring and Tracking Wet Nitrogen Deposition at Rocky Mountain National Park

Product Type: 

Contractor Report

Year: 

2014

Author(s): 

Morris, K., A. Mast, D. Clow, G. Wetherbee, J. Baron, C. Taipale, T. Blett, D. Gay, and J. Heath

Suggested Citation: 

Morris, K., A. Mast, D. Clow, G. Wetherbee, J. Baron, C. Taipale, T. Blett, D. Gay, and J. Heath. 2014.  2012 Monitoring and Tracking Wet Nitrogen Deposition at Rocky Mountain National Park. NPS/NRSS/ARD/NRR—2014/757. Fort Collins, Colorado: National Park Service. 1-24 p.

1. Background Information on the Nitrogen Deposition Reduction Plan

In 2004, a multi‐agency meeting including the Colorado Department of Public Health and Environment (CDPHE), the National Park Service (NPS), and the U.S. Environmental Protection Agency (U.S. EPA) was held to address the effects and trends of nitrogen deposition and related air quality issues at Rocky Mountain National Park (RMNP). These agencies signed a Memorandum of Understanding (MOU) to facilitate interagency coordination, calling the effort the “Rocky Mountain National Park Initiative.” After much collaboration, the MOUagencies (CDPHE, NPS, and U.S. EPA) issued the Nitrogen Deposition Reduction Plan (NDRP) in 2007, which was endorsed by the three agencies and the Colorado Air Quality Control Commission (AQCC). The NDRP and other related documents are available on the CDPHE website: http://www.colorado.gov/cdphe/rmnpinitiative.

As part of the NDRP, the NPS adopted and the MOU agencies endorsed a wet deposition level of 1.5 kilograms of nitrogen per hectare per year (kg N/ha/yr) as an appropriate science‐based threshold for identifying adverse ecosystem effects in RMNP. This threshold is based on decades of research and is the “critical load” of wet nitrogen that can be utilized by sensitive ecosystems within RMNP before detrimental changes occur (Baron 2006). To achieve this threshold, referred to as the resource management goal, the MOU agencies have chosen a glidepath approach. This type of approach anticipates gradual improvement over time and is a commonly used regulatory structure for long‐term, goal‐oriented air quality planning.

The glidepath approach allows for the resource management goal for RMNP to be met over the course of 25 years. The baseline wet deposition at Loch Vale in RMNP was 3.1 kg N/ha/yr based on the 5-year rolling average annual data from 2002 to 2006. The first interim milestone was based on a reduction of wet nitrogen deposition from baseline conditions to a 2.7 kg N/ha/yr 5-year rolling average in 2012. Subsequent milestones will be assessed at 5-year intervals until the resource management goal of 1.5 kg N/ha/yr 5-year rolling average is achieved in the year 2032...