* Stream gages: Measure the height and velocity of water flow in rivers and streams.
* Rain gauges: Measure the amount of precipitation (rain or snow) that falls in a given area.
* Snow pillows: Measure the amount of snow that accumulates on the ground.
* Lysimeters: Measure the amount of water that seeps into the ground from the surface.
* Soil moisture sensors: Measure the amount of water in the soil.
* Groundwater monitoring wells: Measure the depth to groundwater and the quality of groundwater.
* Dataloggers: Record and store data from stream gages, rain gauges, snow pillows, lysimeters, soil moisture sensors, and groundwater monitoring wells.
* Geographic Information Systems (GIS): Software used to create and analyze maps and other spatial data.
* Hydrologic models: Computer models used to simulate the movement of water in watersheds.
* Field equipment: Field equipment used by hydrologists may include hip waders, rain gear, a hat, sunglasses, sunscreen, a flashlight, a first-aid kit, a notebook, and a pen or pencil.