Our monitoring and research program is focused on eleven core study lakes linked through common hydrologic, climatic, edaphic, and biogeographic systems. Intensive monitoring of these lakes is leveraged to learn about lakes both regionally and globally.
In 1981, seven northern lakes, located in north central Wisconsin, were chosen to represent marked differences in size, morphometry and habitat diversity, in thermal and climatic features, in species richness and assemblies, and in biological productivity. Sparkling Lake and Crystal Lake have been experimentally manipulated by NTL and the Wisconsin Department of Natural Resources regularly stocks many lakes, sets bag limits and regulates shoreline maintenance. Research is based out of Trout Lake Station, which along with the seven core study lakes, is located within the Northern Highland-American Legion State Forest, Vilas County, on ancestral Ojibwe land.
In 1994, four southern lakes were added. These four eutrophic lakes in southern Wisconsin were chosen in a 2×2 design of urban vs. agricultural setting and headwater vs. lower in the landscape. Lake Mendota and Lake Wingra have been experimentally manipulated by NTL. All lakes are managed for recreational use with regular fish stocking, bag limits, shore regulations, and macrophyte mowing activities. Research is based out of the Hasler Lab on UW-Madison’s campus, which occupies ancestral Ho-Chunk land.
Please see Trout Lake Station’s land acknowledgment statement.
Lake Attributes
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Northern Lake Attributes
| Crystal Bog (27-2) | Trout Bog (12-15) |
Crystal Lake | Big Muskellunge Lake | Sparkling Lake | Allequash Lake | Trout Lake | |
| Latitude | 46.008 | 46.041 | 46.003 | 46.021 | 46.008 | 46.038 | 46.029 |
| Longitude | -89.606 | -89.686 | -89.612 | -89.612 | -89.701 | -89.621 | -89.665 |
| Elevation (m) | 503 | 499 | 502 | 500 | 495 | 494 | 492 |
| Area (ha) | 0.6 | 1 | 37.5 | 363.4 | 63.7 | 164.2 | 1565.1 |
| Mean Depth (m) | 1.7 | 5.6 | 10.4 | 7.5 | 10.9 | 2.9 | 14.6 |
| Maximum Depth (m) | 2.5 | 7.9 | 20.4 | 21.3 | 20 | 8 | 35.7 |
| Shoreline Length (km) | 0.285 | 0.369 | 2.3 | 16.1 | 4.3 | 9.5 | 25.9 |
| Landscape Position | High | high | high | medium | medium | low | low |
| Shoreline development | low | low | low (campground) | moderate | moderate | low | moderate |
| Days of ice cover | 149 | 151 | 134 | 136 | 133 | 142 | 129 |
| Water Temperature (°C) | 19.5 | 17.7 | 21.5 | 21.7 | 21.7 | 22.1 | 20.7 |
| pH | 5.2 | 4.9 | 6.3 | 7.4 | 7.4 | 7.6 | 7.5 |
| Alkalinity (µeq/L) | 23 | 32 | 42 | 592 | 688 | 884 | 907 |
| Conductance (µS/cm) | 12 | 23 | 13 | 55 | 105 | 97 | 104 |
| DOC (mg/L) | 11.1 | 23.8 | 2.0 | 3.2 | 3.3 | 4.4 | 2.5 |
| Total P (µg/l) | 22.1 | 51.3 | 12.8 | 12.0 | 12.4 | 24.0 | 10.3 |
| Total N (µg/l) | 698 | 1140 | 229 | 390 | 307 | 389 | 271 |
| DRSi (µg/l) | 379 | 1166 | 50 | 180 | 3352 | 7008 | 4307 |
| Secchi Depth (m) | 1.2 | 0.9 | 6.5 | 6.3 | 5.8 | 3.1 | 5.3 |
| Number of fish species | 1 | 3 | 24 | 34 | 30 | 36 | 42 |
| Experimental Manipulations | Thermal manipulation, Smelt removal, Cisco introduction | Crayfish removal, Smelt removal, Cisco introduction |
- Ice cover duration: Mean duration from 2000-2023
- Water temperature: Mean summer (JJA) temperature from 0-2 m from 2000-2021
- Secchi depth: Mean summer (JJA) temperature from 0-2 m from 2000-2020
- pH, alkalinity, DOC, Total N, Total P, dissolved reactive silica, specific conductance: Mean concentrations during spring and fall mixed periods from 2000-2018
Southern Lake Attributes
| Fish Lake | Lake Mendota | Lake Wingra | Lake Monona | |
| Latitude | 43.287 | 43.099 | 43.053 | 43.063 |
| Longitude | -89.652 | -89.405 | -89.425 | -89.361 |
| Elevation (m) | 261 | 259 | 259 | 258 |
| Area (ha) | 80.4 | 3961.2 | 136.2 | 1359.8 |
| Mean Depth (m) | 6.6 | 12.8 | 2.7 | 8.2 |
| Maximum Depth (m) | 18.9 | 25.3 | 4.2 | 22.5 |
| Shoreline Length (km) | 4.3 | 33.8 | 5.9 | 20.9 |
| Landscape Position | high | low | high | low |
| Shoreline development | high | high | high | high |
| Days of ice cover | 88 | 109 | 93 | |
| Water Temperature (°C) | 24.6 | 23.2 | 24.2 | 23.9 |
| pH | 8.1 | 8.4 | 8.6 | 8.4 |
| Alkalinity (µeq/L) | 3179 | 3781 | 3823 | 3583 |
| Conductivity (µS/cm) | 280 | 412 | 500 | 434 |
| DOC (mg/L) | 8.6 | 5.8 | 6.6 | 7.1 |
| Total P (µg/l) | 24 | 107 | 49 | 88 |
| Total N (µg/l) | 1074 | 1500 | 832 | 1010 |
| DRSi (µg/l) | 528 | 1800 | 8870 | 950 |
| Secchi Depth (m) | 1.7 | 2.7 | 1.0 | 2.0 |
| Number of fish species | 26 | 43 | 29 | 41 |
| Experimental Manipulations | Food web manipulation | Carp removal |
- Ice cover duration: Mean duration from 2000-2023
- Water temperature: Mean summer (JJA) temperature from 0-2 m from 2000-2021
- Secchi depth: Mean summer (JJA) temperature from 0-2 m from 2000-2020
- pH, alkalinity, DOC, Total N, Total P, dissolved reactive silica, specific conductance: Mean concentrations during spring and fall mixed periods from 2000-2018