Part II: Looking for Harvey’s Impacts on Galveston Bay

Hurricane Harvey was an historic event for Houston and the entire Galveston Bay region. Devastating floods wrecked neighborhoods and businesses and the recovery and rebuilding process is still ongoing. While we all waited for the floodwaters to recede and work their way through our riverine and bayou watersheds towards Galveston Bay, scientists started thinking about what the impacts would be for Galveston Bay itself, and how we were going to ask and answer those questions.

The Galveston Bay Report Card was specifically designed to examine the Bay and its watershed one year at a time by analyzing indicators of Bay health. The impacts of a major storm like Harvey need to be investigated through a different method: by looking at the immediate and longer-term impacts and viewing those in the context of the larger system with respect to chronic stressors, and over time as the Texas Coast and communities along it continue to change. The Report Card can provide this context, but not the in-depth analysis of Hurricane Harvey’s impacts on Galveston Bay. Other research projects undertaken by the coastal research community engage in those in-depth analyses.

Immediately after Hurricane Harvey, everyone’s priority was safety. Normal monitoring programs and sampling schedules were put on hold while emergency efforts took precedent. As the immediate and obvious threats to human welfare were addressed, new threats became apparent. Agencies, scientists and safety experts started looking at bacteria in the flood waters, toxic chemical spills, Superfund sites, toxic sediments picked up and moved to different areas of the bay, low salinity and changes to the fish and wildlife populations, including commercial species such as oysters. To evaluate these questions properly and thoroughly takes proactive preparation and time. The scientific community rallied quickly and hundreds of thousands of dollars of research projects were designed and started, in many cases as soon as it was safe to navigate a boat in Galveston Bay. These special studies will help define the long-term impacts of Harvey on Galveston Bay.

Galveston Bay is usually a mixture of salt and fresh water, and the organisms that live there have adapted to and depend on that mixture and variability. While estuaries like Galveston Bay need fresh water to support a healthy ecosystem, too little water during drought and too much water too quickly during floods can change the structure and function of the ecological community. The most immediate impact of Hurricane Harvey on Galveston Bay and its ecosystem were extremely low salinities in Galveston Bay that persisted as far south as the Bolivar Roads─the main inlet to Galveston Bay from the Gulf of Mexico─for over two weeks. The extended period of low salinity after Harvey altered the distribution of fish and wildlife and stressed the bay’s resident communities like oysters and dolphins. In an otherwise healthy system, we expect recovery to occur with time.

Each year there are hundreds of chemical and oil spills in Galveston Bay. The number and volume of spills has declined over time, but along with air emissions, they continue to be a part of Galveston Bay’s past and present-day existence. Galveston Bay and particularly the Houston Ship Channel has chronic pollution issues relating to persistent organic chemicals including organochlorine pesticides, PCBs, dioxins, polycyclic aromatic hydrocarbons (PAHs); and inorganic compounds such as fertilizers and mercury. Harvey’s flooding caused or exacerbated spills in the region including those of chemicals and oil.

The long-term impacts of Harvey’s spills are still being studied and the best place to look for persistent pollutants in the bay is in sediments and the tissues of fish and shellfish (i.e. blue crab). When oil or chemicals are spilled in Galveston Bay, wind, sunlight, water, microbes work to break down the chemicals, releasing some to the air, diluting others, and allowing the heaviest and most environmentally persistent fractions of the spill to settle into the sediments. The chemical compounds that remain in the sediments can remain and cause problems for years, depending on the nature and quantity of the chemicals. To follow the fate of these chemicals in the sediments and the potential threat to aquatic life, the Texas Commission on Environmental Quality (TCEQ) and federal and local agency partners monitor the levels of toxics in sediments.

Unfortunately, samples are expensive to analyze, so these monitoring programs are targeted─they choose specific chemicals and the most likely areas to sample. For the toxics in sediment parameters analyzed for the 2018 Galveston Bay Report Card, 51 samples were collected by the TCEQ post-Harvey on 11/30/2017 at three different monitoring locations: 1) Houston Ship Channel at San Jacinto Park, 2) Houston Ship Channel/Buffalo Bayou in the turning basin, and 3) at the Vince Bayou and Houston Ship Channel confluence. Of those 51 sediment samples, 47 had concentrations of contaminants below detection limits (too low to be accurately measured by the monitoring devices) – leaving only five toxics in sediment samples with measurable concentrations.

Sampling the sediments and fish tissues for the dangerous pollutants left behind after a spill is much more efficient than monitoring the water for these contaminants where they more likely to be evaporated, diluted, weathered, and broken down. It is important to identify, report and follow spills as soon as they happen so that they can be contained, the materials can be identified, and emergency management steps can be taken as soon as possible. Rapid response can mean the difference between a small manageable problem and bay-wide contamination. For more info on oil spill response in Galveston Bay, read about how GBF acts as the community volunteer coordinating entity during an active spill in the Central Texas Coastal area.

Bacterial indicators are highlighted under the “Public Health Risk/Recreation” section of the Report Card, because of input from the public. Residents asked us “Is it safe to swim in Galveston Bay?” Bacteria are monitored for “contact recreation” like swimming, kayaking and boating to ensure that that humans are not likely to become ill from inadvertently swallowing water as they play. We tend to see higher bacteria levels after rain events because the rain water picks up bacteria from the land and carries it all to Galveston Bay in one big pulse. Two bacteria parameters (E. coli and Enterococci) are monitored by the TCEQ and its partners and the Texas Department of State Health Services and used by the Galveston Bay Report Card to indicate potential public health risk from fecal waste pollution during contact recreation. More than 2,300 bacteria samples were collected in 2017 with 2,071 samples collected pre-Harvey and 245 samples collected post-Harvey across the region.

Harvey’s flood waters also carried massive quantities of litter, trash and debris from the riverine and bayou watersheds to Galveston Bay. Clean ups around the region are ongoing and have removed more debris than usual, but there is still so much left to remove. One of the effects of trash is that it can make flooding worse by clogging drains and culverts. Litter and trash removal are essential to not only protecting the bay, but also protecting citizens from flooding exacerbated by debris as well as dangerous debris in flood waters. Galveston Bay organizations are pursuing proactive research into the sources and types of waterway trash and debris to better target prevention and cleanup activities. By keeping trash out of our bayous and bay, we can make our waterways safer for humans and wildlife.

Galveston Bay’s fish, shellfish, bird and oyster populations may or may not suffer long-term impacts from Hurricane Harvey. We will have to wait for 2018 data to know whether there were any short-term effects on populations. The Texas Parks and Wildlife Department, Texas Colonial Waterbird Society, Department of Health State Services, TCEQ, and others will continue to monitor the populations and conditions of organisms in the Bay for years to come and look for ways to ensure their resiliency in future hurricanes.