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Updated June 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 Pollutant Reduction Opportunity Report [March 2008: 451 Pages - 19.MB] was a basin-wide analysis which quantified load reductions achievable from implementing various levels of pollutant control efforts. Together the Tech and PRO Reports provided the technical basis for the development of various strategies capable of achieving the interim clarity challenge target (equivalent to an annual average Secchi disk depth of 77-88 feet) within 20 years.
To evaluate political acceptability of the alternative strategies, a public/stakeholder participation series was launched in the fall of 2007 and continued through spring of 2008. More than one half dozen meetings were held with the
Pathway Forum and local agencies who will be responsible for TMDL implementation. The iterative process involved receiving stakeholder feedback in order to refine several initial strategies which were created based on the results of the PRO analysis. The outcome of the process was a recommended strategy based on best available science and which received broad stakeholder support. The Integrated Water Quality Management Strategy (IWQMS) Project Report [395 Pages -9.7MB] describes in detail the recommended strategy born from the process. You may also view a slide presentation that provides an overview of the results and outcomes of the PRO and IWQMS projects [26 slides 1.8MB ].
What's next?
Production of the Final Lake Tahoe TMDL has begun. It is anticipated that the document will be completed in the summer of 2008, upon which it will 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. However, the Final TMDL should be available for adoption sometime in 2009.
Please stay tuned to this webpage for periodic updates. If you would like additional information, you may contact Jason Kuchnicki at 775-687-9450.
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March 20th Nevada TMDL Implementers Meeting
