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Need for Advanced Stormwater Treatment at Lake Tahoe. John E. Reuter & Dave Roberts Tahoe TMDL Research Program. Lake Tahoe: A Changing Ecosystem. Significant portions are urbanized Increased resident population Millions of tourists Peak VMT >1,000,000 miles/day
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Need for Advanced Stormwater Treatment at Lake Tahoe John E. Reuter & Dave Roberts Tahoe TMDL Research Program
Lake Tahoe: A Changing Ecosystem • Significant portions are urbanized • Increased resident population • Millions of tourists • Peak VMT >1,000,000 miles/day • Loss of wetland and runoff infiltration • Extensive road network • Land disturbance - soil erosion • Air pollution
Unraveling Cause(s) for Declining Water Clarity • Nutrients stimulate algae • Fine-sediments directly reduces clarity (1-20 µm) • Progressive accumulation leads to long-term decline • Management strategy - P, N, sediment control • TMDL, EIP & other plans are addressing load reduction
TMDL Development Phases Phase I - Determines Current Loading - Determines Basin-wide Load Reduction Needs Phase II - Identify Load Reduction Possibilities - Allocates Pollutant Load Reductions - Implementation Plan Phase III -Implementation and Monitoring - Adaptive Management framework - Predetermined Review Periods
Tahoe TMDL Phase 2 • Preliminary finding suggest that in many urban areas at Tahoe, traditional BMPs may not be capable of meeting the needed levels of pollutant reduction. • New approaches/technologies may be required. • Implementers must be given a full range of load reduction options. • In 2004 Tahoe Basin one of 14 projects selected nation-wide to receive A USEPA Targeted Watershed grant.
Tahoe TMDL Phase 2 • New approaches under consideration at Tahoe: • Mitigation of air-borne pollutants • Hydrologic controls to reduce runoff • Stream channel erosion • BMP maintenance • Advanced localized or centralized stormwater treatment • Collaborative research by Phil Bachand & Assoc., UC Davis, Caltrans and CSUS-OWP has been examining use of flocculants and coagulants as a possible means of enhancing treatment either in separate treatment systems or associated with an existing BMP.