How 123 River Stations Track What Flows Into the Chesapeake Bay

Why it matters

The lands and waters of the Chesapeake Bay watershed provide more than $100 billion in economic benefits, and meeting the region's clean-water goals should raise that. Meeting them needs accurate, timely information on the watershed's rivers and streams. The Chesapeake Bay nontidal monitoring network (NTN) — a partnership of local, state and federal agencies and others — was set up in 2004 to provide it. The U.S. Geological Survey analyzes its data to show how much nitrogen, phosphorus and sediment reach the bay through its nontidal rivers, giving decision-makers a basis for restoration and conservation.

What is measured

123 NTN stations across the 64,000-square-mile watershed measure streamflow — how much water moves through a river — reported online every hour, useful for recreation and essential for managing floods and droughts. Water samples are taken every month and during storms to compute:

• load — the yearly amount of nutrients or sediment passing a station;
• trend — the change in load over at least 10 years.

Figure 1. The network's monitoring stations, with photos of a staff member collecting a water sample and USGS staff sharing information with local partners. USGS.

Figure 2. An example of streamflow and water-quality samples at a network station. USGS.

Partners and costs

Twenty-five groups fund the network, and seven of them collect its data. Nearly every station — 110 of 123 — has more than one funder. The U.S. Environmental Protection Agency is the largest single funder, but the other 24 partners together pay more than half of the costs.

Figure 3. The 25 funding partners; the seven in vests collect monitoring data. USGS.

Figure 4. Funding by partner — thicker lines mean more money. USGS.

A year of streamflow and water-quality data costs about $7.6 million — an investment in monitoring that guides billions of dollars of clean-water work.

Figure 5. From samples to decisions. USGS; the fact sheet notes this graphic was made with the generative AI tool Adobe Firefly Vector 3 and checked by its authors.

Growing with the need

The network began with 85 stations; 38 have been added where monitoring was lacking. Continuous water-quality monitors at 30 stations now measure conditions every 15 minutes, reported hourly for real-time decisions. As the region works toward its clean-water goals, the USGS and its partners will keep using the network to inform local decisions.

Sources

Based on U.S. Geological Survey, "Using monitoring and partnerships to provide management-relevant information about Chesapeake Bay rivers," Fact Sheet 2025–3045; a work of the United States government in the public domain. It cites Phillips and McGee (2014) and the U.S. Office of Management and Budget (2024) for the economic figures.