This data release contains water-quality and discharge data collected in Rocky Mountain National Park (RMNP), Colorado by the U.S. Geological Survey (USGS) from 10/1/2010 through 9/30/2019 using in-situ sensors and field meters. Data were collected for the purpose of quantifying exchange fluxes of dissolved carbon dioxide (CO₂) from streams. Parameters include daily mean dissolved CO₂, water temperature, atmospheric pressure, and discharge at seven stream sites and one groundwater spring (DailyData.csv). Hourly mean dissolved CO₂, CO₂ partial pressure (pCO2), water temperature, atmospheric pressure, and dissolved oxygen are presented from 10/1/2016 to 9/30/2017 at one of the stream sites (AndrewsHourlyData.csv). Discrete measurements of dissolved CO₂ are presented for hyporheic samples collected at one site during 2000 (AndrewsHyporheicData.csv) and for a synoptic survey of groundwater springs conducted during summer 2018 (SpringsData.csv).