Bacteria Results

The Water Monitoring Team collects valuable water quality data including Enterococci bacteria concentrations around the Bay. Enterococci are a group of  indicator bacteria that indicates the presence or absence of fecal matter in the water and the potentially harmful microorganisms associated with fecal waste.

The most recent Enterococci bacteria concentrations for each location are recorded on the Bacteria Results Map below.

Is My Water Swimmable?

Water Monitoring Team volunteers who are specially certified as Bacteria Samplers collect a small amount of water to be tested for Enterococci. Testing is completed at the Galveston Bay Foundation’s Bacteria Monitoring Lab by a specially trained volunteer and GBF staff. Each site that has been monitored for bacteria concentrations is indicated by a colored dot on the Bacteria Results Map below.

  • Green indicates sites that have a low concentration of bacteria (below 35 CFU/100mL) at the most recent sampling event
  • Yellow indicates sites that have a medium concentration of bacteria (between 35 and 104 CFU/100mL) at the most recent sampling event
  • Red indicates sites that have a high concentration of bacteria (above 104 CFU/100mL) at the most recent sampling event and are considered unsafe for swimming.

What levels are considered “safe?”

The EPA standards for enterococci in a body of water to be safe to swim are a single grab of 104 MPN and a geometric mean of 35 MPN. MPN stands for Most Probable Number, and is a statistical estimate of the concentration of bacteria colonies in the water.

What is being done to address high bacteria levels?

In order to address bacteria impairments, GBF worked with local, regional, and state-level stakeholders and the Texas Commission on Environmental Quality (TCEQ) to develop the Upper Gulf Coast Oyster Waters TMDL Implementation Plan. This community-based plan, which is more simply called the Galveston Bay Bacteria Reduction Plan, lays out the major sources of concern and recommended management measures for reducing bacteria levels to standards that are safe for oyster consumption. Learn more at our Bacteria Reduction Plan webpage.

What causes enterococci to enter our waterways?

Fecal matter can enter our waterways from the following sources:

  • Wastewater treatment facilities
  • Sanitary sewer overflows
  • Malfunctioning septic systems
  • Boat sewage
  • Stormwater runoff
  • Wildlife & pets

Activities to reduce fecal bacteria pollution include:


Internship Publications

Each summer, GBF hosts two water quality interns for 12 weeks. The interns are responsible for sampling, analyzing results, and presenting the findings at summer’s end. Take a look at what our interns have created! To learn more about our summer internships, check out the Water Quality Internships page!

Theodore Driscoll – Summer 2018

Tino Quiocho – Summer 2018 

Emily Innes – Summer 2017

Carolyn Hembree – Summer 2017

Kelsey McCraw – Summer 2016

Jakob Gunderson-Summer 2015

Alyssa Schultz-Summer 2015

Water Quality Intern Presentations – Summer 2015

Tanu Uppal-Summer 2014

Winston Lee-Summer 2014

Ryan Bare-Summer 2013


This event is supported by the Gulf Research Program of the National Academies of Sciences, Engineering, and Medicine under award number


NOAAThis project is funded in part by a Texas Coastal Management Program Grant approved by the approved by the Texas Land Commissioner pursuant to National Oceanic and Atmospheric Administration Award No. NA16NOS4190174.