National Lakes Assessment

EPA and its state and tribal partners conducted a survey of the nation's lakes, ponds and reservoirs in 2007 and will begin a second survey in 2012. This National Lakes Assessment is designed to provide statistically valid regional and national estimates of the condition of lakes. It uses a probability-based sampling design to represent the condition of all lakes in similar regions sharing similar ecological characteristics. Consistent sampling and analytical procedures ensure that the results can be compared across the country. The National Lakes Assessment helps build state and tribal capacity for monitoring and assessment and promotes collaboration across jurisdictional boundaries in the assessment of water quality.

NLA 2012

• Number of Sample Sites: 904
• Revisit Sites: 96

Types of Sites:

The following map displays the base, oversample, and state supplemental sites that may be sampled during the 2012 NLA Field Season.

• Base - The original 904 sites selected to be surveyed
• Oversample - Sites that will substitute for the base sites if determined unsuitable for the survey (not in design, not reachable, not sampleable)
• State Supplemental - some states had the ability to add on additional sample sites for state-scale surveys, these are the additional sites
  

NLA 2007

• NLA 2007 Site Selection Fact Sheet (April 2006) (PDF) (2 pp, 197K, About PDF)

NLA 2012

Manuals are currently being developed and will be posted when available. 

NLA 2007

• 2007 NLA Field Operations Manual (PDF) (104 pp, 9.6M, About PDF)
• 2007 NLA Quality Assurance Project Plan (PDF) (132 pp, 1.3M, About PDF)

Data collected for each parameter sampled in the 2007 National Lakes Assessment (NLA) are available for downloading at the following link: 

National Lakes Assessment Data

Report:

• 2007 National Lakes Assessment Report April 2010 (PDF) (118 pp, 8MB, About PDF)
• National Lakes Assessment: Technical Appendix (January 2010) (PDF) (63 pp, 580K, About PDF)

 Communication:

• Watershed Academy Webcast: "National Lakes Assessment: Reporting on the Condition of the Nation's Lakes" (January 5, 2010)
• Federal Register Notice: National Lakes Assessment Draft Report (PDF) (2 pp, 49K, About PDF)

The 2012 NLA is currently in the planning stages. Tasks currently underway:

• Site Evaluation - states are evaluating the sites for the survey next year to determine if they are "target"
• Manual Development - Field Operations Manual, Lab Operations Manual, and Quality Assurance Project Plan are in development
• Indicator Decision Making - determining what indicators will be used for this next round of the 2012 NLA
• Logistical Planning - setting up contracts for logistics
• Electonic Field Form Development - hoping to roll out electronic field forms this year
• Lab Verification - looking at labs that may want to participate in the surveys and verifying quality assurance information

The EPA conducts the National Lakes Assessment in collaboration with states, tribes, and other federal agencies. In addition to partnering on the national survey, many states choose to augment the selection of lakes sampled within their boundaries to assemble a statistically-valid picture of the lakes in their state.

NLA 2007

Examples of state-wide statistical surveys:

• Minnesota National Lakes Assessment Project
• Washington Department of Ecology National Lakes Survey
• Vermont and the Survey of the Nation's Lakes (PDF) (5 pp, 336K, About PDF)   (5 pp, 336K)

Other Surveys/Studies:

• National Lakes Fish Tissue Study