North Temperate Lakes
US Long-Term Ecological Research Network

North Temperate Lakes LTER: Color - Trout Lake Area 1989 - current

Abstract
Color is measured four times per year in the seven northern study lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes, unnamed lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog]) on water samples that are filtered in the field through 0.45 micron capsule filters (0.45 um nuclepore membrane filters before 2015). A spectrophotometer is used to quantify color in the lab as absorbance units, at 1nm intervals between the wavelengths of 200 and 800 nm. All values are given as measurements at the path length of the employed cuvette and should be divided by the cuvette length for a comparable value at a pathlength of 1 cm. Sampling Frequency: 4 times annually. Number of sites: 7.
Dataset ID
87
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Water samples for color are collected at the deepest part of the lake four times per year: February under ice, spring mixis, August stratification, and fall mixis. The samples are surface water collected with a peristaltic pump and tubing, filtered in the field through 0.45 micron capsule filters ( 0.45u polycarbonate membrane filters before 2015). A wavelength scan from 800 to 200nm is run, using a 5cm rectangular quartz cell in a Beckman Coulter Model DU800 single beam spectrophotometer. Any samples that display absorbance values above 2AU are run again from 400 to 200nm using a 1cm quartz cuvette, as values above 2AU are not considered valid. Blank values in the dataset are from a deionized water scan run as a first sample after instrument blanking, and are reported alongside the scans but are not subtracted from the scan values.
Protocol Log: 1990 -- Scans run using a 10cm cylindrical cell on a Kontron spectrophotometer. 2001 -- we added scans in a 1cm cell for samples with absorbance greater than 2AU. July 2008 -- changed to Beckman Coulter DU800 spectrophotometer, and changed from 10cm to 5cm cell.
Short Name
NTLPH07
Version Number
32

North Temperate Lakes LTER: Lake Levels 1981 - current

Abstract
Lake level is measured during the open water season for the seven primary lakes in the Trout Lake area (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes and unnamed lakes 27-02 [Crystal Bog], and 12-15 [Trout Bog]) using Solinst level loggers in stilling wells logging at 30 minute intervals. Lake level elevation is also manually measured several times each season using a survey of benchmarks of known elevation to calibrate the level loggers. Prior to 2017, lake level was measured with staff gauges placed near the shoreline. Staff gauges were read every two weeks as part of LTER routine sampling. Values presented in the database are the water elevation in meters above sea level. Sampling Frequency: before 2017, every two weeks. 2017 to present, every 30 minutes. Number of sites: 7.
Dataset ID
30
Date Range
-
LTER Keywords
Maintenance
ongoing
Metadata Provider
Methods
Methods are described in abstract
Short Name
NTLPH02
Version Number
27

North Temperate Lakes LTER: Secchi Disk Depth; Other Auxiliary Base Crew Sample Data 1981 - current

Abstract
Secchi disk depth is measured in the deepest part of each lake for the eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, Trout lakes, unnamed lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Fish, Mendota, Monona and Wingra). The disk is circular, 20 cm in diameter, and has alternating black and white quadrants. It is lowered using a calibrated Kevlar rope to minimize stretching. Readings are made on the shaded side of the boat both with and without the aid of a plexiglass viewer. The points at which the disk disappears while being lowered and reappears while being raised are averaged to determine Secchi depth. Auxiliary data include time of day, air temperature, cloud cover, wave height, wind speed and direction and whether the lake was ice covered on the sampledate. Sampling Frequency: fortnightly during ice-free season - every 6 weeks during ice-covered season for the northern lakes. The southern lakes are similar except that sampling occurs monthly during the fall and typically only once during the winter (depending on ice conditions). Number of sites: 11
Dataset ID
31
Date Range
-
LTER Keywords
Maintenance
ongoing
Metadata Provider
Methods
see abstract for secchi disc measurements. Otherwise, these are observations made by the crew while out sampling.
Short Name
NTLPH03
Version Number
30

North Temperate Lakes LTER: Physical Limnology of Primary Study Lakes 1981 - current

Abstract
Parameters characterizing the physical limnology of the eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, Trout, bog lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Mendota, Monona, Wingra and Fish) are measured at one station in the deepest part of each lake at 0.25-m to 1-m depth intervals depending on the lake. Measured parameters in the data set include water temperature, vertical penetration of photosynthetically active radiation (PAR; not measured on lakes Mendota, Monona, Wingra, and Fish), dissolved oxygen, as well as the derived parameter percent oxygen saturation. Sampling Frequency: fortnightly during ice-free season - every 6 weeks during ice-covered season for the northern lakes. The southern lakes are similar except that sampling occurs monthly during the fall and typically only once during the winter (depending on ice conditions). Number of sites: 11
Core Areas
Dataset ID
29
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Light (PAR) extinction coefficient is calculated by linearly regressing ln (FRLIGHT (z)) on depth z where the intercept is not constrained. FRLIGHT(z) = LIGHT(z) or DECK(z) where LIGHT(z) is light measured at depth z and DECK(z) is light measured on deck (above water) at the same time. For open water light profiles, the surface light measurement (depth z = 0) is excluded from the regression. For winter light profiles taken beneath the ice, the first light data are taken at the bottom of the ice cover and are included in the regression. The depth of uppermost light value is equal to the depth of the ice adjusted by the water level in the sample hole, i.e., the depth below the surface of the water. The water level can be at, above or below the surface of the ice. If the water level was not recorded, it is assumed to be 0.0 and the calculated light extinction coefficient is flagged. If ice thickness was not recorded, a light extinction coefficient is not calculated. For light data collected prior to March, 2007, light values less than 3.0 (micromolesPerMeterSquaredPerSec) are excluded. For light data collected starting in March 2007, light values less than 1.0 (micromolesPerMeterSquaredPerSec) are excluded. Except for bog lakes before August 1989, a light extinction coefficient is not calculated if there are less than three FRLIGHT values to be regressed. For bog lakes before August 1989, a light extinction coefficient is calculated if there are least two FRLIGHT values to be regressed. In these cases, the light extinction coefficient is flagged as non-standard. FRLIGHT values should be monotonically decreasing with depth. For light profiles where this is not true, a light extinction coefficient is not calculated. For samples for which light data at depth are present, but the corresponding deck light are missing, a light extinction coefficient is calculated by regressing ln (LIGHT (z)) on depth z. Note that if actual deck light had remained constant during the recording of the light profile, the resulting light extinction coefficient is the same as from regressing ln(FRLIGHT(z)). In these cases, the light extinction coefficient is flagged as non-standard. Oxygen and Temperature: We sample at the deepest part of the lake, taking a temperature and oxygen profile at meter intervals from the surface to within 1 meter of the bottom using a YSI Pro-ODO temporDO meter. We sample biweekly during open water and approximately every five weeks during ice cover. Protocol Log: Prior to 2011, we used a YSI Model 58 temporDO meter.
Short Name
NTLPH01
Version Number
30

North Temperate Lakes LTER: Groundwater Levels 1984 - current

Abstract
Water levels in monitoring wells are measured several times throughout the year. The number of monitored wells has ranged over the study period from 19 to 44 wells. Currently, 37 wells are being monitored 4 - 5 times per year. The wells are scattered throughout the Trout Lake hydrological basin and the data are used to calibrate and test regional groundwater flow models. In addition (see related data set - Groundwater Chemistry), water chemistry is measured annually in a subset of 11 of these wells to characterize regional groundwater chemistry in the Trout Lake area. Sampling Frequency: varies - generally from 4 - 9 times a year Number of sites: 44
Dataset ID
9
Date Range
-
LTER Keywords
Maintenance
ongoing
Metadata Provider
Methods
Standard water level measurements in ground water wells. See abstract for more methods descriptions.
Short Name
NTLGW01
Version Number
22

North Temperate Lakes LTER: High Frequency Water Temperature Data - Sparkling Lake Raft 1989 - current

Abstract
The instrumented raft on Sparkling Lake is equipped with a thermistor chain that measures water temperature from depths ranging from the surface to 18m at intervals from 0.5 to 3m throughout the water column. The surface temperature sensors are attached to floats so that they are as close to the surface as feasible. The raft on Sparkling Lake is also equipped with a dissolved oxygen sensor and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, evaporation rates, and lake metabolism. Estimating the flux of solutes to and from lakes requires accurate water budgets. Evaporation rates are a critical component of the water budget of lakes. Data from the instrumented raft on Sparkling Lake includes micrometeorological parameters from which evaporation can be calculated. Raft measurements of relative humidity and air temperature (2 m height), wind velocity (1, 2, and 3 m heights), and water temperatures are combined with measurements of total long-wave and short-wave radiation data from a nearby shore station to determine evaporation by the energy budget technique. Comparable evaporation estimates from mass transfer techniques are calibrated against energy budget estimates to produce a lake-specific mass transfer coefficient for use in estimating evaporation rates Sampling Frequency: one minute; averaged to hourly and daily values as well as higher resolution values such as 2 min and 10 min. Number of sites: 1
Dataset ID
5
Data Sources
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
see abstract for methods description
Related Sites
Short Name
NTLEV02
Version Number
22

North Temperate Lakes LTER: High Frequency Meteorological and Dissolved Oxygen Data - Sparkling Lake Raft 1989 - current

Abstract
The instrumented raft on Sparkling Lake is equipped with a dissolved oxygen and CO2 sensors, a thermistor chain, and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, evaporation rates, and lake metabolism. Estimating the flux of solutes to and from lakes requires accurate water budgets. Evaporation rates are a critical component of the water budget of lakes. Data from the instrumented raft on Sparkling Lake includes micrometeorological parameters from which evaporation can be calculated. Raft measurements of relative humidity and air temperature (2 m height), wind velocity ( at 1, 2, and 3 m heights; but beginning in 2008, only at 2 m) ,and water temperatures (from thermistors placed throughout the water column at intervals varying from 0.5 to 3m) are combined with measurements of total long-wave and short-wave radiation data from a nearby shore station to determine evaporation by the energy budget technique. Comparable evaporation estimates from mass transfer techniques are calibrated against energy budget estimates to produce a lake-specific mass transfer coefficient for use in estimating evaporation rates. After correcting for flux to or from the atmosphere and vertical mixing within the water column, high frequency measurements of dissolved gases such as carbon dioxide and oxygen can be used to estimate gross primary productivity, respiration, and net ecosystem productivity, the basic components of whole lake metabolism. Other parameters measured include precipitation, wind direction (beginning in 2008), and barometric pressure (beginning in 2008). Sampling Frequency: one minute; averaged to hourly and daily values as well as higher resolution values such as 2 min and 10 min. Number of sites: 1
Core Areas
Dataset ID
4
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The instrumented raft on Sparkling Lake is equipped with a D-Opto dissolved oxygen sensor, a thermistor chain, and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, evaporation rates, and lake metabolism. Estimating the flux of solutes to and from lakes requires accurate water budgets. Evaporation rates are a critical component of the water budget of lakes. Data from the instrumented raft on Sparkling Lake includes micrometeorological parameters from which evaporation can be calculated. Raft measurements of relative humidity and air temperature (2 m height), wind velocity ( at 1, 2, and 3 m heights; but beginning in 2008, only at 2 m) ,and water temperatures (from thermistors placed throughout the water column at intervals varying from 0.5 to 3m) are combined with measurements of total long-wave and short-wave radiation data from a nearby shore station to determine evaporation by the energy budget technique. Comparable evaporation estimates from mass transfer techniques are calibrated against energy budget estimates to produce a lake-specific mass transfer coefficient for use in estimating evaporation rates. After correcting for flux to or from the atmosphere and vertical mixing within the water column, high frequency measurements of dissolved gases such as carbon dioxide and oxygen can be used to estimate gross primary productivity, respiration, and net ecosystem productivity, the basic components of whole lake metabolism. Other parameters measured include precipitation, wind direction (beginning in 2008), and barometric pressure (beginning in 2008). Sampling Frequency: one minute; averaged to hourly and daily values as well as higher resolution values such as 2 min and 10 min.Dissolved oxygen sensors: 2004-2006: Greenspan Technology series 1200; 2007-2016: Zebra-Tech Ltd. D-Opto; 2018+: OTT HydrolabCO2 sensors: 2018+: ProOceanos MiniCO2 for dissolved CO2; Eosense Inc. eosGP for atmospheric CO2
Related Sites
Short Name
NTLEV01
Version Number
33

North Temperate Lakes LTER: High Frequency Water Temperature Data - Sparkling Bog North Buoy 2008 - 2012

Abstract
The instrumented buoy on Sparkling Bog North is equipped with a thermistor chain that measures water temperature at the surface, at 0.25 m and at every .5 m from 0.5 m to 4.5 m. The surface temperature sensors are attached to floats so that they are as close to the surface as feasible. The buoy is also equipped with a dissolved oxygen sensor, meteorological sensors, a CO2 sensor and a YSI AutoProfiler that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Prior to May 2009, data were collected at 1 minute or 10 minute intervals. Since May 2009, data are being collected each minute. Hourly and daily water temperature averages are computed from high resolution data. Hourly and daily values may not be current with high resolution data. In 2008, the instrumented buoy was deployed in Sparkling Bog North from March 24 to November 10. In 2009, the buoy was deployed on the ice on March 7 and was not removed for the winter of 2009 to 2010. Sampling Frequency: varies for instantaneous sample. Generally 1 minute or 10 minutes. Number of sites: 1
Dataset ID
228
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The instrumented buoy on Sparkling Bog North is equipped with a thermistor chain that measures water temperature at the surface, at 0.25 m and at every .5 m from 0.5 m to 4.5 m. The buoy is also equipped with a dissolved oxygen sensor, meteorological sensors, a CO2 sensor and a YSI AutoProfiler that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Prior to May 2009, data were collected at 1 minute or 10 minute intervals. Since May 2009, data are being collected each minute. Hourly and daily water temperature averages are computed from high resolution data. Hourly and daily values may not be current with high resolution data. In 2008, the instrumented buoy was deployed in Sparkling Bog North from March 24 to November 10. In 2009, the buoy was deployed on the ice on March 7 and was not removed for the winter of 2009 to 2010. Sampling Frequency: varies for instantaneous sample.
Related Sites
Short Name
NSPBBUOY2
Version Number
18

North Temperate Lakes LTER: High Frequency Meteorological and Dissolved Oxygen Data - Sparkling Bog North Buoy 2008 - 2012

Abstract
The instrumented buoy on Sparkling Bog North is equipped with a dissolved oxygen sensor, a thermistor chain, and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Data are usually collected either at 1 minute or 10 minute intervals. The D-Opto dissolved oxygen sensor is 0.5m from the lake surface, thermistors are at the surface, at 0.25 m and at every .5 m from 0.5 m to 4.5 m, and meteorological sensors measure wind speed, wind direction, relative humidity, and air temperature. The buoy is also equipped with a CO2 monitor and a YSI AutoProfiler that measures several parameters including dissolved oxygen, water temperature, conductivity, pH, ORP, turbulence and chlorophyll-a. After correcting for flux to or from the atmosphere and vertical mixing within the water column, high frequency measurements of dissolved gases such as carbon dioxide and oxygen can be used to estimate gross primary productivity, respiration, and net ecosystem productivity, the basic components of whole lake metabolism. Sampling Frequency: varies for instantaneous sample. Generally 1 minute or 10 minutes. Number of sites: 1
Core Areas
Dataset ID
227
Date Range
-
Maintenance
completed
Metadata Provider
Methods
see abstract for methods description
Related Sites
Short Name
NSPBBUOY1
Version Number
20

North Temperate Lakes LTER: High Frequency CO2 and YSI AutoProfiler Data - Sparkling Bog North Buoy 2008

Abstract
The instrumented buoy on Sparkling Bog North is equipped with a CO2 monitor and a YSI AutoProfiler that measures several parameters including dissolved oxygen, water temperature, conductivity, pH, ORP, turbulence and chlorophyll-a. The buoy is also equipped with a thermistor chain and a D-OPTO dissolved oxygen sensor at depth .5 m as well as meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Data are usually collected either at 1 minute or 10 minute intervals. Sampling Frequency: varies for instantaneous sample. Generally 1 minute or 10 minutes. Number of sites: 1
Core Areas
Dataset ID
229
Date Range
-
Instrumentation
<p>YSI AutoProfiler</p>
Maintenance
completed
Metadata Provider
Methods
see abstract for methods description.
Related Sites
Short Name
NSPBBUOY3
Version Number
19
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National Science Foundation | LTER Network | Center for Limnology        

This material is based upon work supported by the National Science Foundation under Cooperative Agreement #DEB-2025982, NTL LTER. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.