**2. Background**

The US Clean Water Act (CWA) of 1972 [2] expresses the national desire to restore and maintain the physical, chemical, and biological integrity of USA waters and requires that information on status and trends be reported every 2 years by the states. Different States vary greatly in their monitoring focus and approaches. It has long been recognized that these reports cannot be combined to create a coherent picture of the degree to which lakes in the USA meet the goals of the CWA [3–9]. Looking back at the history of national lake assessments, it is clear that our focus in assessing lake condition has shifted over time as each new threat to lake quality emerged. In the 1960s–1970s, our focus was the "cultural eutrophication" of lakes, that is, the nutrient enrichment of lakes through human activities, via point or nonpoint sources of organic and inorganic nutrients. This enrichment led to everything from "unsightly" algal growth to health problems associated with recreational contact. When extreme, these algal blooms eventually led to low dissolved oxygen levels as the algae died and decayed. The low dissolved oxygen ultimately led to die-off of sensitive fish communities in many lakes. These concerns about eutrophication led to the first ever national lake survey in the USA, the National Eutrophication Survey (NES) [10]. The survey focused on lakes near population centers that were likely subjected to point-source release of nutrients or oxygen demanding compounds. Over 800 lakes suspected of having problems were sampled during this survey using a targeted approach. Ultimately, these concerns led to the funding of the Clean Lakes Program, a Congressionally funded program managed by the fledgling Environmental Protection Agency to provide states and communities with funding to solve specific problems with individual lakes.

The concern about eutrophication and desire to engage the public through citizen monitoring continued into the 1990s. In 1994, the National Secchi Dip-In program was implemented. The Dip-In is a volunteer effort in which citizens from various localities send in their Secchi Depth readings (a measure of lake water clarity) for lakes of interest during a particular week during the summer. This event continues under the sponsorship of the North American Lake Management Society [11].

The 1980s saw increasing concerns about releases of nitrogen and sulfur compounds into the atmosphere and the deposition of these acidic compounds onto lakes and stream watersheds in poorly buffered landscapes. When inquiring into the extent of the problem at the time, William Ruckelshaus, the EPA Administrator at the time, was rumored to have said something along the lines of "What do you mean you don't know how many acid lakes there are?" A definitive answer to this question was not possible at that time for several reasons, including the uncertainty in extrapolating results from site-specific studies to regional or national populations of lakes [12]. These concerns, in Europe and North America, particularly in highly visible regions like the Adirondacks, eventually led to the implementation of the National Acidic Precipitation Assessment Program (NAPAP). Key projects within NAPAP were the National Surface Water Surveys (NSWS), probability-based surveys of lakes (and streams) that set out to document how many acidic lakes and streams there were in the U.S. and how these systems might be changing in response to the 1990 Clean Air Act Amendments [12–14].

Following the completion of the initial NAPAP-sponsored surveys, EPA began to ask whether there might be a better, more consistent approach to directly address the CWA objectives for assessing the condition of lakes and other important ecological resources rather than mounting new surveys for each new problem that arose. The Environmental Monitoring and Assessment Program (EMAP) was a research

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*Jewels across the Landscape: Monitoring and Assessing the Quality of Lakes and Reservoirs…*

1991 to 1995 in the New England states, New Jersey, and New York [16–18].

program designed to develop this approach [6, 15] with a focus on CWA objectives. These research efforts culminated, for lakes, in the implementation and completion of the EMAP Northeastern Lakes Regional Demonstration Project conducted from

As the EMAP research efforts on lake, stream, river, wetland, and estuary monitoring demonstrated their potential effectiveness, the US Office of Management and Budget (OMB) directed the EPA Office of Water to partner with the individual states of the USA to implement the EMAP concepts on a national scale for all waterbody types under the National Aquatic Resources Surveys (NARS). The first National Lake Assessment (NLA) was conducted in 2007 with recurrent surveys in 2012 and 2017 and planned surveys for every 5 years following. The description below outlines the conceptual and practical basis for the lakes monitoring efforts

Three aspects of the NLA make up the overall conceptual approach – the selection of indicators, the approach (survey design) for selecting sites to sample and making inferences to all lakes, and the strategy (response design) for acquiring data at each site for all indicators [6, 19]. This conceptual approach ensures that the NLA will address the main goal of the CWA as well as address the five big questions most

Past surveys of lakes have pursued individual stressors or anthropogenic problems and measured them, for example, the National Eutrophication Survey focused on nutrients, phosphorus in particular, and the National Surface Water Surveys (NSWS) under NAPAP focused on acidification. The NLA, under NARS, is intended to have a broader perspective by using a variety of indicators to examine the overall health of lakes and ranking the importance of individual anthropogenic stressors. This perspective drove the NLA to focus on indicators related to the attribute of "biological integrity" referenced in the CWA [2] to describe "condition" of lakes. In addition, indicators of "physical integrity" and "chemical integrity" describe the relative importance of human-mediated disturbances impacting lake condition. The survey design plays a critical role in the overall approach within the NARS and the NLA. Frequently, surveys are developed with little attention to the final statements that are intended to be made from the data. The National Eutrophication Survey, for example, was based on a targeted judgment sample of 817 lakes potentially influenced by nutrient inputs from domestic wastewater treatment plants. Without statistically representative site selection, the only conclusions that could be reliably made from the data were about those 817 specific lakes. The Great Secchi Dip-In acquires data from thousands of lakes each year. The results provide

*DOI: http://dx.doi.org/10.5772/intechopen.92286*

are taking place as part of the NLA.

**3. Conceptual approach**

frequently asked by the public:

2.How big is the problem?

1.Is there a problem with the condition of lakes?

4.Is the problem getting better or worse?

5.What is causing the problem?

3.Is the problem widespread or localized in hot spots?

*Jewels across the Landscape: Monitoring and Assessing the Quality of Lakes and Reservoirs… DOI: http://dx.doi.org/10.5772/intechopen.92286*

program designed to develop this approach [6, 15] with a focus on CWA objectives. These research efforts culminated, for lakes, in the implementation and completion of the EMAP Northeastern Lakes Regional Demonstration Project conducted from 1991 to 1995 in the New England states, New Jersey, and New York [16–18].

As the EMAP research efforts on lake, stream, river, wetland, and estuary monitoring demonstrated their potential effectiveness, the US Office of Management and Budget (OMB) directed the EPA Office of Water to partner with the individual states of the USA to implement the EMAP concepts on a national scale for all waterbody types under the National Aquatic Resources Surveys (NARS). The first National Lake Assessment (NLA) was conducted in 2007 with recurrent surveys in 2012 and 2017 and planned surveys for every 5 years following. The description below outlines the conceptual and practical basis for the lakes monitoring efforts are taking place as part of the NLA.
