Water Quality Summary

A good way to gauge the health of Galveston Bay is to assess the levels of life-sustaining nutrients and oxygen. Too many nutrients can cause algae blooms that deplete oxygen and even kill marine life. However, the plant life that sustains the bay food web requires nutrients to survive. Water quality grades in the 2019 Report Card reflect conditions in the Bay in 2018. The levels of nutrients and dissolved oxygen found in the 2018 samples were most often at acceptable levels for supporting diverse and healthy aquatic life. However, the issues that exist are primarily due to runoff and wastewater from human activity.

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A
Grade

What We Can do

Nitrogen

Nitrogen is important to the Bay because it stimulates plant growth. But too much nitrogen can cause an algae bloom, which can deplete oxygen in the water and kill aquatic life. In 2019, nitrogen concentrations in regional waterways were above state standards in one percent of samples collected from Galveston Bay, and 15 percent of samples collected from the rivers and bayous surrounding Galveston Bay.

The majority of watersheds in the Galveston Bay region receive an A grade. However, some of the region’s most urbanized watersheds (Addicks Reservoir, White Oak Bayou, Greens Bayou, Houston Ship Channel, Brays Bayou, and Sims Bayou) received B grades, and Barker Reservoir received a D. The West Bay watershed also received a grade of B.

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Nitrogen in Water

Nitrogen levels have been steadily improving in recent years. How did Galveston Bay’s levels fare this year?

What We Can do

Keep Excess Nitrogen Out of Our Waterways

  • Follow fertilizer directions carefully and don’t overfertilize. Going organic is a great way to reduce the amount of fertilizer you use!
  • Leave as much of your property unpaved as possible.
  • Plant a rain garden that collects rainwater and allows it to soak into the soil.
A

Galveston Bay Nitrogen

A

Rivers and Bayous Nitrogen

Be frugal with water and fertilizer use – Don’t fertilize your local waterway

Phosphorus

Phosphorus, like nitrogen, is a nutrient that stimulates plant growth. But too many nutrients can lead to algae blooms, which can deplete oxygen in the water and kill aquatic life. In 2019, phosphorus concentrations were above state screening levels in three percent of samples collected from Galveston Bay, and 41 percent of samples collected from the rivers and bayous surrounding the Bay.

Many southern and eastern watersheds in the Galveston Bay region receive the grade of A. However, the region’s most urbanized watersheds extending from Clear Creek northward to West Fork San Jacinto in Montgomery County continue to receive B, C and D grades. These watersheds reflect some of the most heavily populated, urban land uses in the region yielding larger volumes of rainfall runoff flowing from yards, parking lots and streets.

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Phosphorus in Water

Did you know phosphorus from detergents and plant fertilizer can harm aquatic habitats around the Bay? Find out how you can help.

What We Can do

Keep Excess Phosphorus Out of Our Waterways

  • Use phosphate-free or phosphate-reduced laundry, dish, and car-washing soaps.
  • Incorporate landscaping techniques that require less fertilizer, like growing a garden with native plants.
  • Control erosion. Phosphorus attaches to soil particles, making erosion a contributor to phosphorus pollution.
A

Galveston Bay Phosphorus

C

Rivers and Bayous Phosphorus

Water sparingly and apply the correct amount of fertilizer to reduce lawn care cost

Dissolved Oxygen

Just as people need oxygen to breathe, adequate oxygen levels in water are required to support aquatic life in Galveston Bay and area bayous. Hypoxia (low-oxygen) and anoxia (no-oxygen) zones are common after large algae blooms in water that is warm, still, and has poor clarity. Benthic (bottom-dwelling) organisms can’t escape or survive in hypoxic conditions. In 2019, dissolved oxygen no samples collected in Galveston Bay had dissolved oxygen levels below the screening levels set for the protection of aquatic life. Levels were below state screening levels in only five percent of samples collected from the rivers and bayous surrounding the Bay. As a result, all of Galveston Bay and its watersheds continue to receive an A grade for dissolved oxygen. This is good news for the Bay and its fish and shellfish populations.

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Dissolved Oxygen in Water

Aquatic life, including fish and shellfish, requires oxygen to survive. How are the Bay’s watersheds doing?

Dissolved Oxygen

Click to learn more about Dissolved Oxygen

What We Can do

Our Actions Impact Oxygen Levels

A

Galveston Bay Dissolved Oxygen

A

Tributary Dissolved Oxygen

Essential for your favorite fishing hole

Want more? Check the grades on other Indicators.

Overview
Water Quality
Pollution Events & Sources
Habitat
Wildlife
Human Health Risk
Coastal Change