Sensitivity Analysis of Multiple Regulatory Tools for Riparian Wetland Assessment to Disturbance Gradients within SW Montana
William Kleindl, Ph.D, Assistant Research Professor, Land Resources and Environmental Sciences
Wetland assessment has been designed to meet multiple goals of federal, state and local agencies such as the Clean Water Act (CWA) 404(b)(1) regulatory guidelines for mitigation, the CWA §305(b) guidelines for states report aquatic conditions, BLM guidelines to manage grazing allotments, and local governments managing non-point pollution sources. However, because of the history of ecological assessment within these agencies, there are a multitude of assessment approaches with various degrees of sensitivities to disturbance. Within Montana, there are 7 separate approaches to assessing riparian areas. As our attention moves toward ecological goods and services and the economic benefits those provide to Montana, future assessments tools of these services will build upon required assessment of ecological condition. However, without a meta-assessment of these multiple conditions tools, it will be difficult to choose the best and most cost-effective approach that provides the best distinction of ecological condition of these sensitive areas.
The Montana Department of Environmental Quality (MT-DEQ) has determined that riparian wetlands receive the most pressure from development within the state. As these wetlands continue to degrade, it has the potential to affect Montana economies in several ways. Montana riparian areas are important for water quality (MT-DEQ 2012), water quantity (MT-DNRC 2015), and recreation (MT-DEQ 2013). Monitoring their status and trends are crucial for the inventory and management of these systems. However, many of the federal, state, and local regulatory agencies within Montana assess wetlands and riparian areas with a wide range of assessment tools to assist with their regulatory needs. These existing tools have broad overlapping area of application and are used for multiple wetland decision actions. These actions can include permits to fill these areas and mitigate for unavoidable impacts, enhancement, preservations, conservation reserve programs, and easements.
This research project will test the relative sensitivities, bias, and other limitations of these models when applied across disturbance gradients within the state. In the 1990 Memorandum of Agreement between US Army Corp of Engineers (ACOE) and US Environmental Protection Agency (EPA), ACOE would ‘strive to achieve a goal of no overall net loss of values and functions’ (USEPA 1990). This memorandum, and subsequent guidance, inspired the development and refinement of most wetland function (e.g. Hydrogeomorphic (HGM) approach) or condition (e.g. Rapid Assessment Methodologies (RAM) approach) assessment tools over the last 25 years. These assessment tools have been developed with the benefit from both a theoretical foundation of ecological processes and a history of biotic and abiotic assessment that is nearly at old as the science of ecology (Kolkwitz and Marsson 1908, Cairns and Pratt 1993, Verdonschot 2000). Today, there are over 400 biological and structural assessment methods applied across a suite of environmental problems (Bartoldus 1999, Diaz et al. 2004, Fennessy et al. 2004, Böhringer and Jochem 2007). EPA has categorized these into a three-tiered approach for monitoring and assessing wetlands: Level 1 - landscape assessments, Level 2 - rapid assessments, and Level 3 – highly-detailed assessments with intensive data collection and analysis (Kentula 2007). Most assessment tools used by States are Rapid - Level 2 Assessments, defined as an assessment that can be done with one-half day in the field and one-half day in the office (Fennessy et al. 2007). Level 2 Rapid Assessments are designed to be a cost-effective and efficient approach to providing the data necessary for permitting decisions-making, and is the most common wetland ecological assessment strategy within the U.S. (Fennessy et al. 2007). It is not uncommon for a state like Montana to have multiple rapid wetland assessment approaches due to historical assessment funding priorities and philosophical discussions within the national wetland assessment community (Stein et al. 2009). Montana State currently has two primary assessment models: 1) MDT Assessment Method (MDT-AM: Berglund and McEldowney 2008) used predominately for Clean Water Act (CWA) §404(b)1 and other permit decisions, and 2) Natural Heritage Ecological Integrity Assessment (NH-EIA: MT-NHP 2013) used to assess wetland condition for CWA §305(b) reporting requirement. But both models are used for a variety of other wetland management needs such as decisions on preservation, enhancement, and mitigation ratios. Several other assessment models were developed in the state, but have not been actively incorporated into the State’s wetland decision framework. These models include three HGM models (Riverine - Hauer et al. 2002a, Inter-Mountain Pothole - Hauer et al. 2002b, and Prairie Pothole - Gilbert et al. 2006), MT- Wetland Rapid Assessment Methodology (Apfelbeck and Ferris 2005), the BLM lentic Properly Functioning Condition (PFC) assessment and the BLM Multi-Indicator Measurements (BLM-MIM) (BLM 2003), and the NRCS Greenline (NRCS-GL) Riparian Assessment (also used by MT-DEQ) (USDA 2012) . Because Montana has several assessment models with overlapping areas of application, we can apply these multiple assessment tools to same wetland to evaluate the relative sensitivities, bias, and other limitations.
As part of Montana States wetland condition reporting obligations under CWA §305(b), the Montana Natural Heritage-EIA have collected data of 65 riparian wetlands. Because these data exist and access to the sites have been previously obtained, out team will use these sites as test cases to 1) cross-compare the MDT-AM, NH-EIA, BLM-PFC, BLM-MIM, NRCS-GL, MT-RAM, and HGM assessment approaches above. We will first determine the landscape development intensity within and adjacent to the sites using established methods (Brown and Vivas 2005, Mack 2006, Kleindl et al. 2015). We will then select up to 10 of those 65 sites in SW Montana stratified across that disturbance gradient. If the existing sites do not extend to the full range of best to worst available sites, we will acquire new locations. We will then develop single data sheets that capture assessment attributes required for all models and R-code to calculate multiple outputs from these attributes. Using the disturbance intensity and other site and landscape land use and land cover factors (e.g. contributing area road density, floodplain width, stream order) we will analyze the distribution of the multiple model results to potential explanatory factors using analysis tools such as principle components analysis and other multivariate approaches. Assessment team bias will be assessed using probability distribution methods similar to Whigham et al. (1999). Ultimately, we will provide a report of our findings, as well as electronic site and spatial data, to MT-DEQ. We present our findings to regional science meetings frequented by regulatory and consultant communities (i.e. MT-AWRA, of the PNW or Rocky Mountain chapters of SWS) as well as the Montana Wetland Council.
Significance of the Project
The wetland assessment is fundamental to Montana’s larger aquatic strategic goals articulated in the States planning efforts (MT-DEQ 2013, MT-DNRC 2015). Specifically, ‘the integration, and use of wetland monitoring and assessment data to inform local planning, protection, restoration, and landscape-level decision-making’ in Montana State’s strategic framework for wetland and riparian area conservation and restoration (MT-DEQ 2013). To meet strategic goals, Montana will likely have a future need to assess wetland and riparian ecosystem goods and services that provide both ecological and economic benefit to the state, specifically in: 1) natural water storage in wetlands and riparian areas as a means to increase water supply within the State as articulated in the Montana State Water Plan (MT-DNRC 2015), 2) non-point pollution mitigation to assist in supporting Montana’s beneficial uses and water quality standards (MT-DEQ 2012), and 3) fishing, hunting, and other aquatic-based recreational activities within the State (e.g. USDA 2018). Future assessments of economic and ecological services will build upon required assessment of ecological condition. However, without a meta-assessment of these multiple tools, it will be difficult to choose the best and most cost-effective approach that provides the best distinction of ecological condition of these sensitive areas. Although there are reviews of existing wetland rapid assessment techniques (e.g. Fennessy et al. 2004), an analysis of the sensitivity of these approaches to disturbance gradients has been limited (i.e. Kleindl et al. 2015) in the relevant literature, nor has such a study been conducted in Montana. Therefore, it is an opportune time to conduct this important effort to understand the sensitivities, bias, and other limitations of these existing tools.