Introduction

Nutrient and Sediment Enrichment in Chesapeake Bay

Monitoring and analysis sites in the nontidal water-quality network

Chesapeake Bay has been adversely affected by nutrient and sediment enrichment. Excess nutrients stimulate algal blooms that decay and consume dissolved oxygen, creating areas of low dissolved-oxygen concentration in the bay. Algal blooms and sediment reduce sunlight needed by underwater grasses. Because of slow improvements in water-quality conditions, the bay was listed as an impaired water body under the regulatory laws related to the Clean Water Act.

The Chesapeake Bay Program

The Chesapeake Bay Program has developed water-quality criteria and is requiring all jurisdictions in the bay watershed to develop and implement watershed implementation plans (WIPs) that would reduce nutrient and sediment loads entering the Bay to levels prescribed by the TMDL by 2025.

The current nontidal monitoring network consists of 117 water-quality monitoring stations that are sampled in a coordinated manner by the Chesapeake Bay Program partnership. Water-quality monitoring is performed by the following partners:

• US Environmental Protection Agency (US EPA)
• Maryland Department of Natural Resources (MD DNR)
• Virginia Department of Environmental Quality (VA DEQ)
• Pennsylvania Department of Environmental Protection (PA DEP)
• West Virginia Department of Environmental Protection (WV DEP)
• Delaware Department of Natural Resources and Environmental Control (DNREC)
• New York State Department of Environmental Conservation (NYSDEC)
• Susquehanna River Basin Commission (SRBC)
• District Department of the Environment (DDOE)

The USGS Role: Reporting Constituent Loads and Trends

The U.S. Geological Survey (USGS), in partnership with the Chesapeake Bay Program watershed water-quality monitoring partnership, routinely reports monthly and annual constituent loads, as well as trends in load, for water-quality monitoring stations across the Chesapeake Bay watershed. These reported loads and trends are developed based on

• continuous streamflow monitoring,
• extensive water-quality sampling, and
• advanced statistical analysis.

How Is Information From the Network Used?

Data from the network help scientists and managers assess water-quality conditions and long-term trends as management practices are implemented to reduce the amount of nutrients (primarily nitrogen and phosphorus) and sediment reaching the streams in the watershed and the bay.

Data also will be used to help measure progress toward meeting the Chesapeake Bay Total Maximum Daily Load (TMDL; see https://www.epa.gov/chesapeake-bay-tmdl ). The TMDL is a "pollutant diet" designed to reduce nutrients and sediment to improve water-quality conditions for fish and underwater grasses in the bay.