Water Quality

PRSound Science

What Impacts Water Quality?

Water quality is influenced by a variety of natural and human factors. Some key contributors include:

• Impervious Surfaces: Roads, rooftops, and parking lots prevent water from soaking into the ground, increasing stormwater runoff that carries freshwater and pollutants into marshes and waterways.
• Stormwater Runoff: Rainwater (which is also fresh water) increases in temperature and speed as it moves over impervious surfaces (vs. natural areas). That water collects pollutants and debris as it moves. In this region, stormwater is often directed to stormwater ponds or swales, where it eventually moves into rivers and creeks as freshwater.
• Agriculture: Fertilizers, pesticides, and animal waste applied to agricultural lands may run off the land and make their way into waterways, increasing nutrient loads and causing algae blooms.
• Climate Change: Rising temperatures, rising sea levels, and shifting precipitation patterns as a result of global climate change are intensifying storms and contributing to rising sea levels in the Port Royal Sound. As a result, we expect to see changes in salinity levels, potentially pH levels, and other issues as a result of increased urban flooding and loss of salt marsh.
• Other Sources: Industrial discharges, failing septic systems, animal waste, and some natural processes can also contribute to changes in water quality.

PRSound Science

Water Quality Data in this Portal

This web interface is designed to make water quality data accessible and actionable for anyone interested in the health of the Port Royal Sound Watershed. This section of the portal provides a window into the health of the Sound by tracking key water quality parameters over time, organized at the HUC12 scale. These metrics act as indicators of ecosystem function, helping us identify trends and potential challenges.

Baseline Parameters

• Dissolved Oxygen (DO): A measure of the oxygen available in the water. Dissolved Oxygen is important to support aquatic life, but many species that live in salt marsh environments have adapted to naturally low DO levels because the anaerobic conditions of marsh mud naturally have low levels of dissolved oxygen. Dissolved oxygen levels will vary throughout the day with turbulence, temperature, and daylight — increasing during daylight hours with photosynthesis, and decreasing at night when respiration continues. Drastic drops in DO can indicate organisms such as bacteria are using up a lot of the available oxygen. Warmer water runoff from roadways can also decrease DO levels.
• Salinity & Conductivity: A measure of the mix of fresh and saltwater in the system. As a primarily ocean-tide-influenced system, salinity levels in the lower portion of the Port Royal Sound (South of the I-95 corridor) tend to be higher than in a typical estuary. This has shaped the ecosystem to be dependent on high-salinity levels. Changes in salinity levels change marsh vegetation composition, which in turn affects where oysters live, fish spawning behaviors, etc. Salinity levels are primarily affected by weather — dropping when freshwater enters the system through rain and stormwater runoff, and increasing in times of drought. Longer-range decreases in salinity indicate more sustained freshwater entering the system, which could be the result of climate or increased impervious surface area.
• Temperature: A measure of how hot or cold the water is, measured in degrees Celsius. Water temperature affects growth rate, metabolism, reproduction, and migration of life in water, including fish, marine mammals, shellfish, bacteria, plankton, algae, etc. Temperature also plays an important role in oxygen retention — increased temperature can also result in decreased dissolved oxygen levels.
• pH: A measure of the relative acidity or alkalinity of the water. Low pH values indicate the water is more acidic; high pH values indicate alkaline water, which in turn determine the solubility and availability of other elements in the water. For example, heavy metals in water with a low pH (acidic) become more toxic. Low pH can also slow the growth and even dissolve shells as it affects calcium carbonate structures. Changes in pH can be caused by atmospheric deposition (acid rain), surrounding rock material, and pollution discharge. Changing pH might also be an indicator of the effects of more atmospheric carbon that is also contributing to climate change.

Pollutant Indicators

• Bacteria: The presence, and the amount of bacteria found in the water, namely Coliform and Enterococci, are used as an indicator for the presence of potentially disease-causing organisms and pathogens in the water. Although these bacteria are generally not disease causing, they're often used to monitor and manage recreational and consumptive uses of waterway. Increased bacteria levels can indicate leaking septic tanks or sewage lines; increases in pet, livestock or wildlife presence (and waste); or changes in land-use, but are also influenced by weather and temperature.
• Nutrients: Measures of nitrogen & phosphorus levels in the water. Nutrients promote primary productivity (phytoplankton growth) in estuarine ecosystems and provide food sources for other estuarine organisms. However, too much can cause negative ecological effects by promoting excessive algae growth, which can cause hypoxic conditions (dead zones). Increasing levels of nutrients can indicate changes in land-use leading to erosion, wastewater discharge, or excess fertilizers running off the land.
• Chlorophyll-a: A measure of the amount of algae and cyanobacteria in water. This serves as an indicator for the presence and rate of growth of algae. One sign of degrading water quality conditions is the increase of algae and cyanobacteria biomass as measured by the concentration of Chlorophyll-a. Increasing levels of Chlorophyll-a may be the effect of excessive nutrient levels and increasing temperatures, which can be caused by human activity.
• Heavy Metals (Zinc, Copper, Lead): A set of measures to detect the presence and amounts of potentially harmful inorganic metals in the water. These metals are more often detected in bottom sediment (because they're heavier than water molecules) and are often associated with urban runoff and industrial activities.

This portal displays data collected about these parameters historically, and moving into today. Combined with contextual information about land use, impervious surface, and weather and tidal data, the goal is to use this data to better understand what is happening in the Port Royal Sound, and to detect changes that point to potential issues before they become a problem.

Mapping HUC12 Watersheds

We use HUC12 subwatersheds — the smallest unit of hydrologic classification from the USGS — to provide localized insights into water quality. Each HUC12 is mapped to display its unique data and how it compares to other HUC12s across the Port Royal Sound Watershed.

• Explore the Map: Click on any HUC12 to see detailed water quality data for that specific area.
• Compare Across the Region: View trends and patterns across multiple HUC12s to understand regional dynamics.

Presenting Ambient Data

We focus on ambient data collected through various monitoring programs overseen by the South Carolina Department of Environmental Services (SCDES). This includes:

• Field Sample Locations: Regularly monitored sites for consistent, ongoing data.
• Random Sample Locations: Sites monitored less frequently, providing supplementary data points.
• Shellfish Monitoring Locations: Site locations based on the presence of oyster beds to determine whether they are safe for human consumption. Fewer parameters are measured at these sites.

The portal integrates these datasets to offer a comprehensive picture of water quality in the region.

Flexible Data Views

• Monthly Averages: View data trends broken down by month to observe seasonal patterns.
• Custom Timeframes: Select specific periods to focus on historical trends, going back to the earliest available data.
• Downloadable Data: Export the data via CSV for deeper analysis or integration into other tools.

Empowering Insight and Action

By mapping and comparing data at the HUC12 level, the portal allows users to:

1. Identify areas with healthy or declining water quality.
2. Understand how each HUC12 compares to the larger watershed.
3. Access raw data for your own further analysis.

This portal is a powerful tool for education, research, and action, connecting our community to the information needed to protect and sustain the Port Royal Sound.