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Pathway 2007 Tackles Soil Health, Air and Water Quality

TitlePathway 2007 Tackles Soil Health, Air and Water Quality
Author/CreatorCobourn, John; Purdy, Shelly; Segale, Heather M.
Related item(s)Press Release available at
Date Original2005-01-11
Summary/DescriptionLake Tahoe Report Segment #145 - "Pathway 2007 Tackles Soil Health, Air and Water Quality" (Air Date: Nov. 29, 2005).
SubjectWater quality -- Tahoe, Lake (Calif. and Nev.)
Soil erosion -- Environmental aspects -- Tahoe, Lake, Region (Calif. and Nev.)
Air -- Pollution -- Tahoe, Lake, Region (Calif. and Nev.)
Air -- Pollution -- Environmental aspects --Tahoe, Lake, Region (Calif. and Nev.)
LocationLake Tahoe (Calif. and Nev.)
Tahoe, Lake (Calif and Nev)
CollectionThe Lake Tahoe Report
Original PublisherLake Tahoe Environmental Education Coalition (
Electronic PublisherUniversity of Nevada, Reno - Department of Teaching and Learning Technologies
Ordering and Permissions InformationFor more information, contact the University of Nevada Cooperative Extension, or 775-832-4138.
Date Digital2006-02-15
RelationWindows Media Player
Resource TypeMoving Image
Contributing InstitutionUniversity of Nevada, Reno
TranscriptionSegment 145 - The Pathway 2007 planners have proposed lofty goals for the future of Tahoe's soil, air and water quality. The goals for these key components of the regional ecosystem are to meet the highest standards for exceptional environmental quality. The water quality goals proposed are to protect human health as well as the health of underwater animals and plants. The goal being discussed is also intended to restore, maintain and protect the waters of Lake Tahoe for purposes of human enjoyment and preserving its rare ecological status as one of the few large, deepwater, ultra-oligotrophic (extremely clear, cold) lakes in the world. With regard to protection of human and environmental health, the proposed desired conditions are to have water that is free from toxic chemicals and controllable pathogens, and that supports desired aquatic habitat, aquatic life, and food web characteristics that would be expected in this clear, cold mountain lake. For Lake Tahoe's water to improve from a transparency depth of 73.6 feet in 2004 to a Secchi depth of 97.4 feet (29.7 meters) that was measured in the late 1960s, lake pollution by fine sediment, nitrogen and phosphorus must be reduced. Runoff and dust containing these pollutants are the main culprits of clarity loss at Lake Tahoe since the 1960s. Scientists working on the proposed Tahoe Total Maximum Daily Load (TMDL) are developing models to estimate the needed pollutant load reductions for achieving the desired lake clarity. A water quality management strategy is being developed as part of the Pathway 2007 process, and it will require further reductions in the delivery of pollutants such as fine sediments, nitrogen and phosphorus to lake waters. Stormwater, tributary streams, groundwater, and atmospheric deposition are all sources of fine sediments and nutrients which affect lake clarity. The environmental thresholds for soils and air quality are closely related to these key pollution sources. For example, stormwater and tributary pollution are the result of increased soil disturbance and too much land coverage in a sub-watershed. Atmospheric deposition of dust (fine sediment) into the lake is likewise a result of impaired air quality. The proposed desired conditions for air quality are divided into three categories: visibility, human health, and lake clarity and forest health. The visibility goals are to maintain at least 72 miles of visual range from Bliss State park and at least 34 miles of visual range at South Lake Tahoe for 90 percent of the year. For half of the days in each year, these visual ranges should be 116 and 58 miles, respectively. The proposed air quality conditions for human health are to have "zero exceedances" of the most restrictive standards for ozone, carbon monoxide and particulate matter anywhere in the basin. Excessive amounts of ozone in the air can also harm the basin's pine trees, but the ozone standard proposed for the human health desired condition should be sufficient to protect forest health. While the standards for air quality have not been determined for lake clarity protection, it is clear that both nutrients and dust can enter the lake through the air. Fine particles that are less than 10 microns in diameter (very small) remain suspended in water, thus reducing water clarity. Therefore, this microscopic size class of particle must be reduced within the air quality standards in order to protect water quality. One difficult tradeoff for Pathway 2007 planners is the need to reduce the amount of forest fuels, often by prescribed burning. Because prescribed burns directly affect air quality, planners will need to decide how to provide maximum benefit to both forest health and air quality objectives in upcoming discussions. The proposed desired conditions for soil conservation include sustaining "soil health" and having development compatible with the soil's capability to respond to urban pressures. The proposed desired condition for soil health is that soils will function at the level of native soils in their capacity to regulate water flow and infiltration, sustain plant and animal life, process nutrients, and filter potential pollutants. The proposed goal for land capability is that "land development and land use are compatible with the amount of use an area can tolerate without sustaining permanent damage to soil vegetation and/or watershed functions. Land disturbance and land coverage should not cause deterioration of stream systems and/or water quality." Before a new land capability standard can be proposed, a thorough review of the Bailey system, Individual Parcel Evaluation System (IPES) plus the land coverage transfer and mitigation system is planned. The new Lake Tahoe Basin Soil Survey, due for release in mid-2006 also factors into this review. Stream environment zones (SEZ), discussed last week in relation to wildlife and fisheries goals, also tie back to both soil conservation and water quality goals. One of the fascinating aspects of the exhaustive Pathway 2007 planning process is the way all the components of our environment (the thresholds) must be considered in relation to each other. As John Muir said, "If you try to pull out any aspect of nature and look at it, you find it is hitched to everything else in the universe." The next scheduled meeting of the Pathway 2007 Forum is the December 1 at the Chateau in Incline Village from 9 am to 4:30 pm. The Forum is a citizen's group that is your direct link to participate in Pathway. Check for more details.

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