This dataset contains raw tier 2 sampling data starting from 2011 for Texas coastal waters related to seagrasses. Parameters measured include chlorophyll a concentration, water depth, dissolved oxygen, light attenuation, pH, salinity, Secchi depth, water temperature, total suspended solids, seagrass canopy height, and seagrass percent cover. Typical species represented within the data include Halodule wrightii, Thalassia testudinum, Syringodium filiforme, Halophila engelmannii, and Ruppia maritima. Sampling takes place at 567 permanent stations in Aransas and Redfish Bays, Corpus Christi Bay, and Upper and Lower Laguna Madre. Latitudes and longitudes for station locations are based on the NAD83 datum. There was limited sampling in 2016. This dataset also includes opportunistic sampling in Little Bay, San Antonio Bay, and Galveston Bay, as well as analytically measured tissue content of carbon, nitrogen, and phosphorus in Halodule wrightii and Thalassia testudinum plant samples collected from Aransas and Redfish Bays, Corpus Christi Bay, and the Laguna Madre along with stable isotope data from those samples. Data are provided in CSV format.