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The Lake Tahoe Interagency Monitoring Program (LTIMP) is an essential part of integrated science in the Lake Tahoe Basin and has provided long-term, consistent, reliable, and accessible tributary monitoring data for decades.
Deteriorating water quality and clarity in Lake Tahoe prompted the initiation of environmental programs in the Lake Tahoe basin. Water-quality data, especially nutrient and sediment data, for streams and ground-water aquifers that discharge to Lake Tahoe are needed to document the local and regional effectiveness of environmental programs and to assure compliance with California and Nevada water-quality management programs. The Lake Tahoe Interagency Monitoring Program (LTIMP) was started in 1979 to help understand why clarity was declining in Lake Tahoe. Currently, LTIMP stream monitoring is a partnership between the United States Geological Survey (USGS), the University of California-Davis (UC Davis), the Tahoe Regional Planning Agency (TRPA), the Lahontan Regional Water-Quality Control Board, and the California Tahoe Conservancy. The USGS continues to collect data necessary to assess the health of Lake Tahoe tributaries and ensure the data are publicly available.
Currently, water managers in Lake Tahoe are concerned about
current tributary nutrient and suspended sediment concentrations and loads (status),
assessing trends in nutrient and sediment concentrations and loads (trends), and
what factors influence the observed status and trends.
Since the late 1980’s, USGS has collected discharge, sediment, and water quality data at seven major drainages as part of LTIMP. Continuous, real-time measurements of turbidity recently were added to LTIMP sites. Similarly, the U.S. Department of Agriculture, National Resources Conservation Service (NRCS) has conducted continuous snowpack and soil monitoring in basin headwaters, with daily snow measurements dating back to the late 1970’s or early 1980’s at most sites. These data can be combined with remotely sensed datasets available from USGS and NASA and analyzed to determine the key factors controlling measured fine sediment and nutrient loads in LTIMP streams draining to Lake Tahoe.
Lake Tahoe Basin data can now be accessed through the Lake Tahoe Hydro Mapper. The Hydro Mapper is an interactive map viewer which allows users to see real-time information on stream flow discharge, stage, nutrient, turbidity, sediment loads, and storage data. Data from NRCS Snow Telemetry (SNOTEL) and National Weather Service Advanced Hydrologic Prediction Service are included with other local and regional hydrologic data, weather radar, watershed extents, and other ancillary geospatial data.
Sources/Usage: Public Domain.
Available Data
USGS Nevada Water Science Center scientists are collecting streamflow and water-quality data at pertinent Lake Tahoe tributaries to estimate nutrient and sediment loads to the lake and assess trends in stream water quality. Within the Lake Tahoe watershed, these data are collected at the following sites:
Water year 2020 streamflow summary for the Upper Truckee River at South Lake Tahoe, USGS Site 10336610.
Monitoring Expansion Following the Caldor Fire
In water year 2022, LTIMP was expanded to monitor impacts of the Caldor fire. Over 10,000 acres were burned in the Upper Truckee and Trout Creek Watersheds. In response, the LTIMP program was expanded to increase the number of storm samples, add analyses of dissolved organic carbon, ammonium, and isotopes of fire-retardant related compounds with funding provided by TRPA. The expanded monitoring will continue for three years with a planned report to summarize the study results.
Lake Tahoe, a large freshwater lake of the eastern Sierra Nevada in California and Nevada, has 63 tributaries that are sources of nutrients and sediment to the lake. The Tahoe watershed is relatively small, and the surface area of the lake occupies about 38% of the watershed area (1313 km2). Only about 6% of the watershed is urbanized or residential land, and as part of a plan to maintain water cl
Since 1980, the Lake Tahoe Interagency Monitoring Program (LTIMP) has provided stream-discharge and water quality data—nitrogen (N), phosphorus (P), and suspended sediment—at more than 20 stations in Lake Tahoe Basin streams. To characterize the temporal and spatial patterns in nutrient and sediment loading to the lake, and improve the usefulness of the program and the existing database, we have (
The terminus of a stream flowing into a larger river, pond, lake, or reservoir is referred to as the stream-mouth reach or simply the stream mouth. The terminus is often characterized by rapidly changing thermal and hydraulic conditions that result in abrupt shifts in surface water/groundwater (sw/gw) exchange patterns, creating the potential for unique biogeochemical processes and ecosystems. Wor
Clarity of Lake Tahoe, California and Nevada has been decreasing due to inflows of sediment and nutrients associated with stormwater runoff. Detention basins are considered effective best management practices for mitigation of suspended sediment and nutrients associated with runoff, but effects of infiltrated stormwater on shallow ground water are not known. This report documents 2005-07 hydrogeol
Lake Tahoe (Nevada-California) has been designated as an 'outstanding national water resource' by the U.S. Environmental Protection Agency, in part, for its exceptional clarity. Water clarity in Lake Tahoe, however, has been declining at a rate of about one foot per year for more than 35 years. To decrease the amount of sediment and nutrients delivered to the lake by way of alpine streams, wetland
A study at the Cattlemans detention basin site began in November 2000. The site is adjacent to Cold Creek in South Lake Tahoe, California. The purpose of the study is to evaluate the effects of the detention basin on ground-water discharge and changes in nutrient loads to Cold Creek, a tributary to Trout Creek and Lake Tahoe. The study is being done in cooperation with the Tahoe Engineering Divisi
Five lakes and their outlet streams in the Lake Tahoe Basin were sampled for nutrients during 2002-03. The lakes and streams sampled included Upper Echo, Lower Echo, Fallen Leaf, Spooner, and Marlette Lakes and Echo, Taylor, and Marlette Creeks. Water samples were collected to determine seasonal and spatial concentrations of dissolved nitrite plus nitrate, dissolved ammonia, total Kjeldahl nitroge
Cattlemans detention basin, South Lake Tahoe, California is designed to capture and reduce urban runoff and pollutants originating from developed areas before entering Cold Creek, which is tributary to Trout Creek and to Lake Tahoe. The effectiveness of the basin in reducing sediment and nutrient loads currently is being assessed with a five-year study. Hydraulic conductivity of the alluvium near
Stream temperature has long been recognized as an important water quality parameter. Temperature plays a key role in the health of a stream’s aquatic life, both in the water column and in the benthic habitat of streambed sediments. Many fish are sensitive to temperature. For example, anadromous salmon require specific temperature ranges to successfully develop, migrate, and spawn [see Halupka and
The Lake Tahoe Interagency Monitoring Program (LTIMP) is an essential part of integrated science in the Lake Tahoe Basin and has provided long-term, consistent, reliable, and accessible tributary monitoring data for decades.
Deteriorating water quality and clarity in Lake Tahoe prompted the initiation of environmental programs in the Lake Tahoe basin. Water-quality data, especially nutrient and sediment data, for streams and ground-water aquifers that discharge to Lake Tahoe are needed to document the local and regional effectiveness of environmental programs and to assure compliance with California and Nevada water-quality management programs. The Lake Tahoe Interagency Monitoring Program (LTIMP) was started in 1979 to help understand why clarity was declining in Lake Tahoe. Currently, LTIMP stream monitoring is a partnership between the United States Geological Survey (USGS), the University of California-Davis (UC Davis), the Tahoe Regional Planning Agency (TRPA), the Lahontan Regional Water-Quality Control Board, and the California Tahoe Conservancy. The USGS continues to collect data necessary to assess the health of Lake Tahoe tributaries and ensure the data are publicly available.
Currently, water managers in Lake Tahoe are concerned about
current tributary nutrient and suspended sediment concentrations and loads (status),
assessing trends in nutrient and sediment concentrations and loads (trends), and
what factors influence the observed status and trends.
Since the late 1980’s, USGS has collected discharge, sediment, and water quality data at seven major drainages as part of LTIMP. Continuous, real-time measurements of turbidity recently were added to LTIMP sites. Similarly, the U.S. Department of Agriculture, National Resources Conservation Service (NRCS) has conducted continuous snowpack and soil monitoring in basin headwaters, with daily snow measurements dating back to the late 1970’s or early 1980’s at most sites. These data can be combined with remotely sensed datasets available from USGS and NASA and analyzed to determine the key factors controlling measured fine sediment and nutrient loads in LTIMP streams draining to Lake Tahoe.
Lake Tahoe Basin data can now be accessed through the Lake Tahoe Hydro Mapper. The Hydro Mapper is an interactive map viewer which allows users to see real-time information on stream flow discharge, stage, nutrient, turbidity, sediment loads, and storage data. Data from NRCS Snow Telemetry (SNOTEL) and National Weather Service Advanced Hydrologic Prediction Service are included with other local and regional hydrologic data, weather radar, watershed extents, and other ancillary geospatial data.
Sources/Usage: Public Domain.
Available Data
USGS Nevada Water Science Center scientists are collecting streamflow and water-quality data at pertinent Lake Tahoe tributaries to estimate nutrient and sediment loads to the lake and assess trends in stream water quality. Within the Lake Tahoe watershed, these data are collected at the following sites:
Water year 2020 streamflow summary for the Upper Truckee River at South Lake Tahoe, USGS Site 10336610.
Monitoring Expansion Following the Caldor Fire
In water year 2022, LTIMP was expanded to monitor impacts of the Caldor fire. Over 10,000 acres were burned in the Upper Truckee and Trout Creek Watersheds. In response, the LTIMP program was expanded to increase the number of storm samples, add analyses of dissolved organic carbon, ammonium, and isotopes of fire-retardant related compounds with funding provided by TRPA. The expanded monitoring will continue for three years with a planned report to summarize the study results.
Lake Tahoe, a large freshwater lake of the eastern Sierra Nevada in California and Nevada, has 63 tributaries that are sources of nutrients and sediment to the lake. The Tahoe watershed is relatively small, and the surface area of the lake occupies about 38% of the watershed area (1313 km2). Only about 6% of the watershed is urbanized or residential land, and as part of a plan to maintain water cl
Since 1980, the Lake Tahoe Interagency Monitoring Program (LTIMP) has provided stream-discharge and water quality data—nitrogen (N), phosphorus (P), and suspended sediment—at more than 20 stations in Lake Tahoe Basin streams. To characterize the temporal and spatial patterns in nutrient and sediment loading to the lake, and improve the usefulness of the program and the existing database, we have (
The terminus of a stream flowing into a larger river, pond, lake, or reservoir is referred to as the stream-mouth reach or simply the stream mouth. The terminus is often characterized by rapidly changing thermal and hydraulic conditions that result in abrupt shifts in surface water/groundwater (sw/gw) exchange patterns, creating the potential for unique biogeochemical processes and ecosystems. Wor
Clarity of Lake Tahoe, California and Nevada has been decreasing due to inflows of sediment and nutrients associated with stormwater runoff. Detention basins are considered effective best management practices for mitigation of suspended sediment and nutrients associated with runoff, but effects of infiltrated stormwater on shallow ground water are not known. This report documents 2005-07 hydrogeol
Lake Tahoe (Nevada-California) has been designated as an 'outstanding national water resource' by the U.S. Environmental Protection Agency, in part, for its exceptional clarity. Water clarity in Lake Tahoe, however, has been declining at a rate of about one foot per year for more than 35 years. To decrease the amount of sediment and nutrients delivered to the lake by way of alpine streams, wetland
A study at the Cattlemans detention basin site began in November 2000. The site is adjacent to Cold Creek in South Lake Tahoe, California. The purpose of the study is to evaluate the effects of the detention basin on ground-water discharge and changes in nutrient loads to Cold Creek, a tributary to Trout Creek and Lake Tahoe. The study is being done in cooperation with the Tahoe Engineering Divisi
Five lakes and their outlet streams in the Lake Tahoe Basin were sampled for nutrients during 2002-03. The lakes and streams sampled included Upper Echo, Lower Echo, Fallen Leaf, Spooner, and Marlette Lakes and Echo, Taylor, and Marlette Creeks. Water samples were collected to determine seasonal and spatial concentrations of dissolved nitrite plus nitrate, dissolved ammonia, total Kjeldahl nitroge
Cattlemans detention basin, South Lake Tahoe, California is designed to capture and reduce urban runoff and pollutants originating from developed areas before entering Cold Creek, which is tributary to Trout Creek and to Lake Tahoe. The effectiveness of the basin in reducing sediment and nutrient loads currently is being assessed with a five-year study. Hydraulic conductivity of the alluvium near
Stream temperature has long been recognized as an important water quality parameter. Temperature plays a key role in the health of a stream’s aquatic life, both in the water column and in the benthic habitat of streambed sediments. Many fish are sensitive to temperature. For example, anadromous salmon require specific temperature ranges to successfully develop, migrate, and spawn [see Halupka and
