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Updated February 2008
Lake Tahoe is world renowned for its striking blue color and amazing clarity. However, research indicates that excessive fine sediments, less than 20 microns, and nutrients, phosphorous and nitrogen, are the pollutants responsible for the trend of declining clarity over nearly the last half century.
For this reason, Lake Tahoe has been listed on Nevada's 303 List for impairment with respect to its beneficial use as a Water of Extraordinary Aesthetic or Ecologic Value. To address this impairment NDEP is collaborating with the California Regional Water Quality Control Board, Lahontan Region (Lahontan) to develop the Lake Tahoe Total Maximum Daily Load (TMDL) for Fine Sediment and Nutrients. The enormous undertaking of the Lake Tahoe TMDL necessitated the breakdown into three distinct phases.
Phase 1 involved the establishment of a comprehensive research program to answer the following questions:
- What pollutants are causing Lake Tahoe's clarity loss?
- How much of each pollutant is reaching Lake Tahoe?
- How much of each pollutant can Lake Tahoe accept and still reach the clarity goal?
The answers to these questions can be found in the DRAFT Lake Tahoe Total Maximum Daily Load Technical Report [341 Pages - 8.4MB]. View a slide presentation [29 Pages - 1.4MB] containing an overview and key results of the science, research and monitoring program.
Phase 2 of the TMDL attempts to answer these questions:
- What are the options for reducing pollutant inputs to Lake Tahoe?
- What strategy should be implemented to achieve the clarity goal?
The DRAFT Pollutant Reduction Opportunity Report [448 Pages - 19.MB] is a basin-wide analysis which quantifies load reductions achievable from implementing various levels of pollutant control efforts. Together the Tech and PRO Reports provide the technical basis for the development of various strategies capable of achieving the interim clarity challenge target within 20 years.
To evaluate political acceptability of the alternative strategies, a public participation series was launched in the fall of 2007. An iterative process of receiving stakeholder feedback and refinement of the proposed strategies resulted in the development of a recommended implementation strategy that has broad stakeholder and agency support. View a slide presentation that provides an overview and key results of this study [43 slides 2.4MB ] . A Technical Memorandum summarizing the strategy development and stakeholder feedback process and is currently in production. Furthermore, final versions of the Tech and PRO Reports are currently in production, which will address stakeholder concerns and comments that were raised during the public participation series.
What's next?
The TMDL Team has developed a proposed approach for conducting the pollutant load allocations. This expression of the distribution of allowable pollutant loads between and within sources is a required element necessary for the TMDL to gain EPA approval. The proposed approach will be vetted through the Lake Tahoe implementation community and presented to the PATHWAY Forum this winter.
Once a final approach for this element is decided upon, production of the Draft Final Lake Tahoe TMDL will commence. It is anticipated this document will be completed in the summer of 2008. The document will then undergo scientific peer review. A formal public comment period will then be scheduled based on the time needed to address the comments received from the peer review process.
Please stay tuned to this webpage for periodic updates!
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February 29th 2008 Meeting
