Frequently Asked Questions

Reservoir levels refer to the water surface elevation measured in feet above sea level. These measurements are taken by electronic sensors installed at USGS (United States Geological Survey) monitoring stations. The sensors continuously record data including water elevation, discharge rate (flow speed in cubic feet per second), and water surface temperature. Our dashboard aggregates this data daily from the USGS Water Services API.

Our system syncs with the USGS federal sensor network daily. Each monitoring station reports water elevation, discharge, and temperature data. While some stations report hourly, our dashboard focuses on the daily values for consistency and reliability. The "Updated" timestamp on each water body page shows the date of the most recent data.

Water elevation (or water level) is measured in feet above mean sea level. For reservoirs and lakes, this number tells you how full the water body is compared to its "full pool elevation" — the maximum designed water level. If a reservoir has a full pool of 1,000 ft and the current elevation is 950 ft, the reservoir is at 95% of its maximum capacity. Lower elevations may indicate drought conditions.

Discharge rate, measured in cubic feet per second (cfs), tells you how much water is flowing through a point in a river or stream. One cfs means one cubic foot of water passes by every second. Higher discharge means faster, more powerful water flow. For reference: 100-500 cfs is typically calm enough for kayaking, while 3,000+ cfs represents fast-moving, potentially dangerous water.

You can find dams and reservoirs near you in several ways: 1) Use the search bar at the top of any page to search by name. 2) Browse our state directory on the homepage to find water bodies in your state. 3) Each water body page includes a Google Maps embed with exact GPS coordinates and a "Get Directions" button. We currently track 12,158 water bodies across 50 states.

Texas has a vast network of lakes, reservoirs, and rivers. On our dashboard, we currently track 704 water bodies in Texas with active USGS monitoring stations. This includes major lakes like Lake Travis, Canyon Lake, Medina Lake, and many more. Visit our Texas Lakes guide for complete data.

California reservoir levels are tracked in real-time on our dashboard. We monitor every reservoir, lake, and river with an active USGS sensor in the state. Major reservoirs like Lake Shasta, Lake Oroville, Folsom Lake, and Don Pedro Reservoir are all included. Visit our California Reservoirs guide for the latest data and capacity percentages.

Whether a lake or reservoir is "full" depends on its current water elevation compared to its full pool elevation. On each water body detail page, we show a capacity percentage bar when full pool data is available. If the current elevation matches the full pool elevation, the lake is at 100% capacity. Many western US reservoirs, particularly in California, Arizona, and Nevada, have experienced significant fluctuations in recent years due to drought and climate patterns.

Generally, water temperatures above 70°F (21°C) are considered comfortable for swimming. Between 60-70°F is chilly but swimmable for most people. Below 60°F, prolonged immersion can lead to cold water shock and hypothermia. Each water body page on our site shows the current water temperature with a safety rating: "Very Cold" (below 50°F), "Cold" (50-65°F), "Warm" (65-78°F), or "Very Warm" (above 78°F).

River flow (discharge) is critical for kayaking safety. As a general guide: Under 500 cfs is usually calm and suitable for beginners. 500-3,000 cfs represents moderate conditions for experienced paddlers. Above 3,000 cfs indicates fast, powerful water — only recommended for expert paddlers. Always check local advisories, wear a life jacket, and verify flow conditions on the day of your trip using real-time data from our river monitoring pages.

Our dashboard focuses on inland water bodies (lakes, reservoirs, and rivers) rather than tidal data. For ocean tide information, we recommend checking NOAA's Tides & Currents website (tidesandcurrents.noaa.gov). However, for lake and reservoir levels, our real-time data can help you plan fishing, boating, and other water activities at inland water bodies.

All hydrological data on USWaterLevels.com is sourced from the United States Geological Survey (USGS) through their Water Services API. The USGS operates thousands of monitoring stations across the country that continuously record water elevation, flow rate, and temperature data. We currently aggregate data from 12,158 active monitoring stations across all 50 states.

Our data is as accurate as the USGS sensor readings it comes from. The USGS is the premier federal science agency for water data in the United States. However, sensors can occasionally malfunction or go offline, which is why we display a "Sensor Offline" notice when recent data is unavailable. We also show the exact date of the most recent reading so you always know how current the data is.

USGS stands for the United States Geological Survey. It is a scientific agency of the United States government that studies the landscape, natural resources, and natural hazards of the country. The USGS operates one of the largest hydrological monitoring networks in the world, with thousands of stream gauges and lake level sensors across all 50 states. Our dashboard makes this public data more accessible and easier to understand.