Save Lake Weir Board has initiated a new lake watch committee to resume regular, systematic lake water testing in Lake Weir. Thanks to the members that volunteered to assist with this effort.  The program summary is as follows:

  • Samples are collected monthly
  • Treated as 3 bodies of water (big lake, sunset harbor, little lake)
  • 3 samples across each body of water per month at the exact geometric location
  • The assigned group will be taking measurements for each of the bodies- consistently – same time, same day, same person, for each body of water

Metrics covered:

  • total ni
  • total ph
  • chlorophyll
  • water clarity
  • true color
  • connectivity

To learn more, click here.  The most current data is through December 2022 and the full report is under the link below.  The report covers all lakes in Marion County – Little Lake Weir data starts on page 93, Sunset Harbor data starts on page 149 and Lake Weir data starts on page 164.  The following excerpt is from the Lake Weir data:

Figure 2. Lake Weir trend plots of year by average. The R2 value indicates the strength of the relations (ranges from 0.0 to 1.0; higher the R2 the stronger the relation) and the p value indicates if the relationis significant (p < 0.05 is significant). Total phosphorus (TP Increasing, R2 = 0.65, p = 0.00), total nitrogen (TN Increasing, R2 = 0.30, p = 0.00), chlorophyll (CHL Increasing, R2 = 0.56, p = 0.00) and Secchi depth (Secchi Decreasing, R2 = 0.49, p = 0.00). 


Key Metrics of Lake Weir

Lake Weir Water Levels compared to Annual Rainfall

54% increase in nitrogen levels since 1985

19% decrease in water clarity since 1985

*Source: St. Johns Water Management District

Lake Weir  – Then and Now                                                                                                                          



Important Studies and Data

Algae Blooms on Lake Weir

Algae Reporting

Have you seen significant algae blooms on or near your lakeshore?  Take a minute to record a picture and upload it to  Reporting the blooms is easy at this site and your diligence will ensure the DEP is aware of the ongoing conditions on Lake Weir. At this site, you can also subscribe to a weekly update delivered to your email for free to follow the testing results for Lake Weir and other Florida area water bodies.