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Overview
Basics
Basics
Understanding the transformation and fate of nutrients in groundwater and surface waters is of critical importance for protecting and managing water resources in lake systems. In this investigation, we collected nutrient samples from groundwater and surface water during a 9-month monitoring period to evaluate the timing and availability of nutrients in the nearshore zone of Lake Tahoe. We estimated seasonal groundwater discharge using continuous hydraulic head measurements in piezometers placed in the shallow lakebed. The results indicate that groundwater and nutrient discharge through the lakebed appear to stimulate periphyton growth along the eulittoral zone of Lake Tahoe.
Completed
2016
2016
2018
$400,000
Dan Segan (dsegan@trpa.gov)
05/05/2018
03/14/2024
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| Location Information | Location Notes |
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Organizations
Organizations
EIP Details
EIP Basics
EIP Basics
04.01.01.0130 - Assessment of groundwater nutrients and periphyton biomass in Lake Tahoe
Performance Measures
Expected Performance Measures
Expected Performance Measures
No expected performance measures set for this project.
Reported Performance Measures
Reported Performance Measures
No annual performance measure accomplishments entered for this project.
Funding
Expected Funding
Expected Funding
$400,000
$400,000
$0
| Total | |||
|---|---|---|---|
| California State Water Resources Control Board (Lahontan) | $200,000 | $200,000 | $0 |
| U.S. Geological Survey (USGS) | $200,000 | $200,000 | $0 |
| Grand Total | $400,000 | $400,000 | $0 |
Reported Expenditures
Reported Expenditures
| Total | 2018 | 2017 | 2016 | |
|---|---|---|---|---|
| California Lahontan Regional Water Quality Control... | $200,000 | $100,000 | $100,000 | $0 |
| U.S. Geological Survey | $200,000 | $100,000 | $100,000 | $0 |
| Grand Total | $400,000 | $200,000 | $200,000 | $0 |
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Other Details
Watersheds
No watersheds set for this project.
Threshold Categories
-
Nearshore
Local and Regional Plans
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Related Projects
Related Projects
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External Links
Notes
Notes
| 03/14/2024 12:50 PM | Dan Segan | Executive Summary: This work sought to answer the following questions: 1) what are the sources of nitrogen (N) and phosphorus (P) in groundwater, and 2) are these sources identifiable in nearshore periphyton? The findings of this effort focused on source identification using stable isotopes of nitrogen and oxygen in groundwater and periphyton. Data collected to identify P sources were inconclusive likely due to carbon interference. To address the question regarding P sources, additional research is needed to refine the field and laboratory methods. The findings from our study are compelling and have important implications for nutrient management in Lake Tahoe. The results indicate the sources of nitrogen to groundwater and periphyton are related to fertilizer and to a lesser extent atmospheric nitrate, manure and septic sources. The process of transport in groundwater to the nearshore is influenced by lake-groundwater mixing, caused by wave action where influx of lake water promotes nitrification of ammonia to nitrate. The data indicates nitrification plays a role in transformation of snow ammonia to nitrate in Ward Creek and nitrification of ammonia fertilizer in groundwater at transect NS3, NS5 and at synoptic periphyton monitoring sites. In periphyton, the higher biomass is associated with lower 15dN values, indicating that nitrification of snow ammonia and ammonia fertilizer and atmospheric nitrate to be the dominate sources. The data collected for this period indicates the highest levels of periphyton biomass is associated 15dN values that fall within with the range of values associated with nitrification of ammonia fertilizer typically associated with synthetic fertilizers. |