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Discharge rates and water temperature of the primary inflow tributary into Falling Creek Reservoir (Vinton, Virginia, USA), also known as Tunnel Branch, were measured at a gauged weir on a 15-minute temporal resolution from May 2013 to December 2023. Falling Creek Reservoir is a drinking water supply reservoir owned and managed by the Western Virginia Water Authority (WVWA). The dataset consists of water temperatures and discharge rates calculated from a pressure transducer deployed by the WVWA in a rectangular weir (15 May 2013 - 06 June 2019) and in a v-notched weir (07 June 2019 - 31 December 2023) at the same site. From 07 June 2019 to 31 December 2023, water temperature and discharge data were also collected from a Virginia Tech-deployed (VT) pressure transducer installed in the same weir. NOTE this verison replaces edi.202.11, where there was an error in calculating the WVWA_Flow_cms from 18 April 2016 15:15:00 EST - 07 June 2019 00:00:00 EST. This is corrected in version edi.202.12. 

Depth profiles of water biogeochemical properties were collected with SeaBird Electronics (SBE) Conductivity, Temperature, and Depth (CTD) profilers from 2013-2023. Data availability differs across years due to additional sensors that have been added or replaced over time. From 2013-2016, profiles were taken with a CTD equipped with an SBE 43 Dissolved Oxygen sensor and an ECO FLNTU sensor for turbidity and chlorophyll. From 2017-2023, profiles were taken with a CTD equipped with an SBE 43 Dissolved Oxygen sensor, an ECO FLNTU sensor for turbidity and chlorophyll, a PAR-LOG ICSW sensor for photosynthetically active radiation, and a SBE 27 pH and ORP (oxidation-reduction potential) sensor. In 2022 and 2023, profiles were also taken with an additional CTD equipped with an SBE 43 Dissolved Oxygen sensor; an ECO Triplet Scattering Fluorescence sensor for CDOM, phycocyanin, and phycoerythrin; an ECO FLNTU sensor for turbidity and chlorophyll; and PAR-LOG ICSW for photosynthetically active radiation. CTD profiles were collected in five drinking water reservoirs in southwestern Virginia, USA. All variables were measured every 0.25 seconds, resulting in depth profiles at approximately ten centimeter resolution. The five study reservoirs are: Beaverdam Reservoir (Vinton, Virginia), Carvins Cove Reservoir (Roanoke, Virginia), Falling Creek Reservoir (Vinton, Virginia), Gatewood Reservoir (Pulaski, Virginia), and Spring Hollow Reservoir (Salem, Virginia). Beaverdam, Carvins Cove, Falling Creek, and Spring Hollow Reservoirs are owned and operated by the Western Virginia Water Authority as primary or secondary drinking water sources for Roanoke, Virginia, and Gatewood Reservoir is a drinking water source for the town of Pulaski, Virginia. The dataset consists of CTD depth profiles measured at the deepest site of each reservoir adjacent to the dam as well as other upstream reservoir sites. The profiles were collected approximately fortnightly in the spring months, weekly in the summer and early autumn, and monthly in the late autumn and winter. Beaverdam Reservoir, Carvins Cove Reservoir, and Falling Creek Reservoir were sampled every year in the dataset (2013-2023); Spring Hollow Reservoir was only sampled 2013-2017 and 2019; and Gatewood Reservoir was only sampled in 2016. 

We measured eddy covariance data and fluxes (carbon dioxide, methane) collected at the deepest site of Falling Creek Reservoir (Vinton, Virginia, USA) every 30 minutes from 04 April 2020 to 31 December 2023. Falling Creek Reservoir is a drinking water supply reservoir owned and managed by the Western Virginia Water Authority (WVWA) as a primary drinking water source. The dataset consists of micrometeorological and flux data collected using an eddy covariance system (LiCor Biosciences, Lincoln, Nebraska, USA) and analyzed with associated Eddy Pro software (Eddy Pro Version 7.0.6), including carbon dioxide and methane fluxes. All analysis scripts are included for data processing and quality assurance/quality control following best practices. 

Hypolimnetic hypoxia has become increasingly prevalent in stratified water bodies in recent decades due to climate change. One primary sink of dissolved oxygen (DO) is sediment oxygen uptake ($${J}_{{O}_{2}}$$$J_{O_2}$). On the water side of the sediment–water interface (SWI),$${J}_{{O}_{2}}$$$J_{O_2}$is controlled by a diffusive boundary layer (DBL), a millimeter-scale layer where molecular diffusion is the primary transport mechanism. In previous studies, the DBL was determined by visual inspection, which is subjective and time-consuming.

In this study, a computational procedure is proposed to determine the SWI and DBL objectively and automatically. The procedure was evaluated for more than 300 DO profiles in the sediment of three eutrophic water bodies spanning gradients of depth and surface area. Synthetic DO profiles were modeled based on sediment characteristics estimated by laboratory experiments. The procedure was further verified adopting the synthetic profiles.

The procedure, which was evaluated for both measured and synthetic DO profiles, determined the SWI and DBL well for both steady and non-steady state DO profiles. A negative relationship between DBL thickness and aeration rates was observed, which agrees with existing literatures.

The procedure is recommended for future studies involving characterizing DBL to improve efficiency and consistency.

 

Ice cover was recorded at Falling Creek Reservoir and Beaverdam Reservoir (both located in Vinton, Virginia, USA) using multiple methods. The ice cover record for Falling Creek Reservoir began in the winter of 2013-2014 and Beaverdam Reservoir beginning in the winter of 2020-2021. Falling Creek Reservoir and Beaverdam Reservoir are owned and operated by the Western Virginia Water Authority as a primary and secondary drinking water source, respectively, for Roanoke, Virginia. These two reservoirs are some of the southernmost waterbodies in the United States that exhibit ice cover during the winter. Given incipient climate change, Falling Creek Reservoir and Beaverdam Reservoir's ice cover data represent an important record of warming for waterbodies in the southeastern United States. Ice cover presence was assessed using multiple methods: visual observation of ice spanning the deep hole (from an observer standing on a reservoir's dam); visual observation via an automated camera deployed near the deep hole; water temperature data from a profile of sensors deployed at a reservoir's deepest site; upwelling shortwave radiation and albedo measured by a meteorological station deployed on a metal structure located over Falling Creek Reservoir's deep hole; and dissolved oxygen sensors deployed at multiple depths at the deep hole of both reservoirs. 

This dataset consists of meteorological variables measured by a research-grade Campbell Scientific meteorological station deployed on the dam of Falling Creek Reservoir (37.3025, -79.83667). Falling Creek Reservoir (Vinton, Virginia, USA), is owned and operated by the Western Virginia Water Authority as a primary water source. The meteorological variables include photosynthetic active radiation, barometric pressure, ambient air temperature, relative humidity, rainfall, wind speed and direction, shortwave radiation, infrared radiation, and albedo. All variables were measured every 5 minutes from 2015-07-07 15:45:00 to 2015-07-13 11:28:00 (YYYY-MM-DD hh:mm:ss) and every minute thereafter to the end of the dataset at 2023-12-31 23:59:00. We applied substantial quality assurance/quality control protocols to the raw observations, as described in the methods. 

We monitored water level and water quality in Beaverdam Reservoir (Vinton, Virginia, USA, 37.31288, -79.8159) with visual observations and high-frequency (10-minute and 15-minute) sensors in 2009-2023. All variables were measured at the deepest site of the reservoir adjacent to the dam. Beaverdam Reservoir is owned and managed by the Western Virginia Water Authority as a secondary drinking water source for Roanoke, Virginia. This data package is comprised of three datasets: 1) BVR_WaterLevel_2009_2023.csv, 2) BVRSensorString_2016_2020.csv, and 3) BVRPlatform_2020_2023.csv. 1) BVR_WaterLevel_2009_2023.csv contains water level observations of the staff gauge by both the Western Virginia Water Authority and the Virginia Tech Reservoir Group LTREB field crew. This dataset spans 2009 to 2023, with data collection still ongoing. 2) BVRSensorString_2016_2020.csv consists of a water temperature profile at ~1-meter intervals from the surface of the reservoir to 10.5 m below the water, complemented by a dissolved oxygen logger at 5 m or 10 m, depending on the time of year. A sonde measuring water temperature, conductivity, specific conductance, chlorophyll a, phycocyanin, total dissolved solids, dissolved oxygen, fluorescent dissolved organic matter, and turbidity was additionally deployed at ~1.5 m depth. This dataset spans 2016 to 2020, with no additional data collection beyond the last observation. The third dataset is BVRPlatform_2020_2023.csv, with data collection still ongoing. This dataset contains: a) a temperature string with 13 temperature sensors deployed ~1 m apart from the surface to 0.5 m above the sediments of the reservoir; b) two dissolved oxygen sensors, one in the middle of the string and one sensor above the sediments; and c) a pressure sensor just above the sediments. The same sonde from the first 2016-2020 dataset is also included in this 2020-2023 dataset, deployed at 1.5 m below the surface. The sensors on the temperature string (thermistors, dissolved oxygen sensors, and pressure sensor) are permanently fixed to the platform and do not change with the water level. In the methods, we describe how to add a depth measurement to each observation. 

Discharge rates at multiple inflow streams into Falling Creek Reservoir (Vinton, Virginia, USA), Beaverdam Reservoir (Vinton, Virginia, USA), and Carvins Cove Reservoir (Roanoke, Virginia, USA) were measured manually using multiple methods from 2019-2023. Falling Creek Reservoir, Beaverdam Reservoir, and Carvins Cove Reservoir are owned and operated by the Western Virginia Water Authority as drinking water sources for Roanoke, Virginia. The dataset consists of discharge rates calculated using one of four methods: handheld flowmate, salt injection, velocity float, or bucket method. Data were collected weekly to monthly from February through October 2019 at Falling Creek and Beaverdam Reservoir, approximately monthly at Falling Creek in 2020-2022, approximately monthly at Carvins Cove in 2021-2022, and approximately seasonally in 2023 at Falling Creek and Carvins Cove. 

Depth profiles of fluorescence-based phytoplankton biomass were sampled using a bbe Moldaenke FluoroProbe during 2014 to 2023 in five drinking water reservoirs in southwestern Virginia, USA. These reservoirs are: Beaverdam Reservoir (Vinton, Virginia), Carvins Cove Reservoir (Roanoke, Virginia), Falling Creek Reservoir (Vinton, Virginia), Gatewood Reservoir (Pulaski, Virginia), and Spring Hollow Reservoir (Salem, Virginia). Beaverdam, Carvins Cove, Falling Creek, and Spring Hollow Reservoirs are owned and operated by the Western Virginia Water Authority as primary or secondary drinking water sources for Roanoke, Virginia, and Gatewood Reservoir is a drinking water source for the town of Pulaski, Virginia. The dataset consists of depth profiles of fluorescence-based phytoplankton biomass measured at the deepest site of each reservoir adjacent to the dam, except in Falling Creek Reservoir, where depth profiles were also taken at four upstream sites ranging from the riverine to the lacustrine zone during 2016-2019. Casts were taken approximately weekly from May-October and monthly from November-April. Casts were collected at Beaverdam and Falling Creek Reservoirs during all years (2014-2023); casts were collected at Carvins Cove Reservoir during 2014-2016 and 2018-2023; casts were collected at Spring Hollow Reservoir during 2014-2016 and 2019; and casts were collected at Gatewood Reservoir in 2015-2016. 

We monitored water quality in Carvins Cove Reservoir (Roanoke, Virginia, USA) with high-frequency (10-minute) sensors in 2020-2023. Carvins Cove Reservoir is owned and managed by the Western Virginia Water Authority as a primary drinking water source. This data package consists of datasets from two separate deployments. First, from July 2020 - August 2021, depth profiles of water temperature were measured on 1-meter intervals using HOBO temperature pendant loggers deployed from 0.1 m below the surface of the reservoir to 10 m depth, and also at 15 and 20 m depth. Additionally, water temperature was measured in the Sawmill Branch inflow at 0.5 m depth using HOBO temperature pendant loggers. Second, from 9 April 2021 - 31 December 2023, depth profiles of water temperature were measured on 1-meter intervals from 0.1 m below the surface of the reservoir to 11 m depth and additionally at 15 and 19 m. A YSI EXO2 sonde measured water temperature, conductivity, specific conductance, chlorophyll a, phycocyanin, total dissolved solids, dissolved oxygen, and fluorescent dissolved organic matter at ~1.5 m depth. A YSI EXO3 sonde measured water temperature, conductivity, specific conductance, total dissolved solids, dissolved oxygen, and fluorescent dissolved organic matter at 9 m depth, which corresponds to the depth of a water outtake valve. The thermistors, EXO3 sonde, and pressure sensor were deployed at stationary, fixed elevations (referred to as positions) deployed off of the dam near the water outtake valves. Due to variable water levels in the reservoir, the depths of these sensors varied over time. In contrast, the EXO2 was deployed on a buoy from 2021-2022 and remained at 1.5 m depth as the water level fluctuated. However, in 2023, the buoy disappeared in a storm, after that the EOX2 was deployed at a stationary elevation as the water level fluctuated around the sensor. At the monitoring site, the reservoir is approximately 19 m deep (reservoir maximum depth is 23 m).