**Abstract**

Use of water chemistry or water quality data as the sole indicator to determine if aquatic ecosystems meet restoration objectives or Clean Water Act criteria is not possible for wetland resources because surface water presence varies across wetland types. The 2011, National Wetland Condition Assessment (NWCA) assessed 967 sites representing 25,153,681 ha of wetland across the conterminous US. Surface water could be collected at 537 sites representing only 41% of the wetland population area and under-representing particular wetland types. These results motivated the authors to introduce the concept of *aquatic resource quality*, the condition of an ecosystem based on the integrated assessment of physical, chemical, and biological indicators, as the goal of monitoring and assessment of aquatic systems. The NWCA is an example of the use of *aquatic resource quality.* The survey successfully reported on wetland condition using a biotic indicator (the vegetation multimetric index) and the relative extent and relative risk of stressors using 10 physical, chemical, and biological indicators to report on *aquatic resource quality*. The NWCA demonstrated that *aquatic resource quality* can be consistently evaluated regardless of surface water presence. Consequently, we recommend *aquatic resource quality* as the goal of aquatic ecosystem monitoring and assessment.

**Keywords:** wetlands, monitoring and assessment, National Wetland Condition Assessment, aquatic resource quality, National Aquatic Resource Surveys, water chemistry, water quality

## **1. A new paradigm:** *Aquatic resource quality*

For many, the terms water quality and water chemistry are synonymous, but others (e.g., Eriksson [1]) recognize a subtle yet important distinction between the terms. While the term water chemistry refers to the chemical composition of the water; water quality implies a value judgment on the suitability of the composition of the water for a specific use. Typically, the composition of the water is defined by chemical characteristics (as in Eriksson [1]), but sometimes physical or biological aspects of the water, such as turbidity, color, or odor, are used. Making a distinction between the definitions of water chemistry and water quality is essential for clear communication. To further avoid the ambiguities surrounding the use these terms,

we introduce the concept of *aquatic resource quality* for reporting based on the physical, chemical, and biological integrity of aquatic resources as outlined in the goals of the Clean Water Act (CWA) [2].

*Aquatic resource quality* is defined herein as the condition of an aquatic ecosystem. Evaluating *aquatic resource quality* requires the integrated use of physical, chemical, and biological indicators to describe the condition of the resource and identify factors negatively affecting the condition [3]. Wetlands are an excellent test case for examining the application of the *aquatic resource quality* concept because traditional use of only water chemistry or water quality to determine whether rivers, streams, and lakes meet CWA criteria is not consistently possible for wetlands. Wetlands do not always have surface water. This is because the surface water in wetlands varies on seasonal and annual time scales, with regimes ranging from permanently flooded to saturated (i.e., substrate is saturated to the surface for extended periods, but surface water is seldom present) to intermittently flooded (i.e., weeks, months, or years may intervene between periods of inundation) [4]. Furthermore, certain wetland types, like fens, are groundwater-driven and rarely have surface water. Because sampling surface water for determination of chemistry is not always possible in wetlands, the adoption of the *aquatic resource quality* concept is required to holistically characterize the wetland resource.

Wetlands are a critical part of the Nation's aquatic resources and are protected under the CWA. Because of this, there is an obligation to include wetlands in monitoring programs for reporting under the CWA—despite the challenges associated with sampling wetlands. Fortunately, there is ample evidence that the wetland resource can be successfully assessed at large scales based on the *aquatic resource quality* concept (e.g., [5–7]). This early research helped inform the development of the National Wetland Condition Assessment (NWCA), which was first conducted in 2011 by the US Environmental Protection Agency (USEPA) to fulfill the objective of determining a baseline for *wetland resource quality* in the conterminous US. The goals of the NWCA were to:


In this chapter, we present a summary of the 2011 NWCA design and methods, and then use national-scale data to report on patterns in the distribution of the wetlands represented by surface water chemistry. Finally, we examine how the NWCA fulfills the more comprehensive objective of reporting on *wetland resource quality* in accordance with the CWA requirements to consider the physical, chemical, and biological integrity of the wetland resource.

## **2. Data collection for the 2011 NWCA**

The following subsections provide a brief overview of the design and field sampling methods used in the NWCA. For details see the 2011 NWCA Site Evaluation

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**Figure 1.**

*Wetland Assessment: Beyond the Traditional Water Quality Perspective*

(https://www.epa.gov/national-aquatic-resource-surveys/nwca).

Guidelines [9], Field Operations Manual [10], Laboratory Methods Manual [11], and Technical Report [12]. These documents are available on the NWCA website

The target population, that is, the specific portion of the wetlands of the conterminous United States (US) to be assessed in the 2011 NWCA was composed of tidal and nontidal wetlands with rooted vegetation and, when present, open water less than 1 m deep, and includes farmed wetlands not in crop production at the time of the survey [8]. The target population was comprised of seven of the wetland classes used in the US Fish and Wildlife Service's (USFWS) Wetlands Status and Trends (S&T) reporting [13]: Estuarine Intertidal Emergent (E2EM), Estuarine Intertidal Forested/Scrub Shrub (E2SS), Palustrine Emergent (PEM), Palustrine Farmed (Pf), Palustrine Forested (PFO), Palustrine Scrub Shrub (PSS), and Palustrine Unconsolidated Bottom/Aquatic Bed (PUBPAB). These classes are an adaptation of those defined by Cowardin et al. [4] and used in USFWS National Wetland

A spatially balanced probability survey design [14–16] was developed using plots from the USFWS S&T Program as a basis for a sample of site locations for the NWCA. The USFWS S&T plots were mapped using 2005 aerial photography. The S&T Program mapped additional plots on the Pacific Coast at the request of the NWCA to assure sites would be selected for sampling along the coast due to the lower frequency of wetland occurrence in the Western US than in other parts of the country (**Figure 1**). The NWCA design allocated site locations by state and wetland class, generating 1800 potential site locations to ensure approximately 900 sites meeting target criteria would be available for sampling [12, 17]. Nine-hundred sites allow evaluation of different wetland types in the conterminous US and five major ecoregions. Ultimately, 967 sites

*Map of the 967 site locations sampled in the 2011 National Wetland Condition Assessment by five Ecoregions: Tidal Saline (TSL), Coastal Plains (CPL), Eastern Mountains & Upper Midwest (EMU), Interior Plains (IPL), and West (W). Note that CPL, EMU, IPL, and W exclusively include freshwater wetlands. The pattern of site locations reflects the distribution of wetlands across the conterminous United States with most wetland* 

*DOI: http://dx.doi.org/10.5772/intechopen.92583*

**2.1 2011 NWCA survey design**

Inventory (NWI) mapping.

from the probability design were sampled (**Figure 1**).

*areas in the East and Southeast and the least in the Midwest and West.*

Guidelines [9], Field Operations Manual [10], Laboratory Methods Manual [11], and Technical Report [12]. These documents are available on the NWCA website (https://www.epa.gov/national-aquatic-resource-surveys/nwca).
