Water Quality in the Guana Ecosystem

By Nikki Dix, Shannon Dunnigan, and Silas Tanner

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Another great reason to love working at a NERR is that we operate at so many levels. We have national, regional, and local programs that steer our research, education, and stewardship of the estuaries within our boundaries. Many of the projects we work on here at the GTM have been guided by our local stakeholders. For example, our oyster monitoring, which began in 2014, was spearheaded by interest in our local oyster populations (remember the Shuck and Tell stories?) and groups like the Oyster and Water Quality Task Force. Another such project was started this past summer by local interest in our Guana Lake/River system.

Guana Lake and Guana River are considered Outstanding Florida Waterbodies and have an interesting history (check out our article in the 2018 State of the Reserve program here). They are within both a state Aquatic Preserve and a National Estuarine Research Reserve, designations intended to protect the health of Guana waters for long-term recreational enjoyment, commercial fishing/oyster harvesting, research, and education.


A view of Guana Lake taken during the sampling event in November 2017


Inspired by momentous community interest, multiple sponsors, including the Audubon Society and the Friends of the GTM Research Reserve, generously funded water quality sampling and subsequent laboratory analyses starting in July 2017. Monthly sampling, a collaboration between GTM NERR and Northeast Florida Aquatic Preserves, occurs during high outgoing tides at five locations: Micklers, Lake Mid, Lake South, River North, and Guana River (see map).

So far, concerning levels of nutrients, algal biomass, and bacteria have been observed.


Chlorophyll figures
Chlorophyll-a data collected since July 2017. Sites are grouped based on the waterbody in which they were collected (the Lake or the River). The annual means thresholds are associated with the waterbody classifications.


Florida’s Department of Environmental Protection (DEP) assesses water quality in state waterbodies every 5 years. The assessment for Guana Lake/River is currently underway. DEP could only use data prior to July 2017 for the current assessment and have insufficient data to assess Guana waterbodies during this cycle. Because of the 5-year cycle, DEP was not considering sampling Guana waterbodies this year to be a high priority, but we reached out and shared our recent concerning results.

They have since worked within DEP to share resources and have agreed to start testing soon if we at the GTM NERR can conduct the field sampling. We plan to partner with Northeast Florida Aquatic Preserves and Florida Fish and Wildlife Conservation Commission’s (FWC) Guana Wildlife Management Area to make it work.

For more about the DEP water quality assessment process visit:


2 Comments Add yours

  1. Kim says:

    I’m glad DEP was responsive! Good job using your data to make something happen.

    Liked by 2 people

  2. Debbie Dix says:

    Glad you all are “on it”! Keep up the good work.

    Liked by 2 people

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