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Why Measure Water Quality at Lake Tahoe?

TitleWhy Measure Water Quality at Lake Tahoe?
Author/CreatorCobourn, John; Purdy, Shelly; Segale, Heather M.
Related item(s)Press Release available at
Date Original2003-01
Summary/DescriptionLake Tahoe Report Segment # 3 - "Why Measure Water Quality at Lake Tahoe?" (Air Date: February 18, 2003). Bob Richards from the University of California at Davis' Tahoe Research Group discusses his ongoing efforts to measure the lake's clarity.
SubjectWater quality -- Tahoe, Lake, Watershed (Calif. and Nev.)
Stream measurement -- Tahoe, Lake, Watershed (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 Digital2004-12-06
RelationRequires Windows Media Player
Resource TypeMoving Image
Contributing InstitutionUniversity of Nevada, Reno
TranscriptionSEGMENT 3: ((Anchor Intro)) We've all heard about the devastating trend at Lake Tahoe. The famous clear blue waters are getting cloudy and more green every year. But how do we know that? In tonight's "Lake Tahoe Report" segment Shelly Purdy takes us aboard a research vessel that's been tracking the downward trend for decades. PACKAGE: ((Nats of boat tugging through water)) ((Nats of Bob putting Secchi disk into water)) ((TRACK 1)) Bob Richards has been throwing his Secchi disk overboard for more than three decades. Rain or shine he is out on the water measuring the clarity of Lake Tahoe. It's really a very simple process. The Secchi disk is like a big white dinner plate. You watch as the disk goes down, and when you can?t see it anymore you simply measure the depth and easily calculate the level of clarity in the water. ((SOT tape 3 @ 23:24 Bob Richards, Tahoe Research Group, University of California - Davis)) "What it shows unfortunately is that over the long term, we've been losing the clarity of the lake at a rate between a foot to a foot and a half a year." ((TRACK 2)) The University of California, Davis first started taking secchi depth readings in 1969. Back then, you could easily see 100 feet down into the water. Today's average is only 60 feet. ((SOT tape 3 @ 25:00 Bob Richards)) "I think I can actually see a change in the color of the water. It's no longer a deep purple blue that it used to be." ((SOT tape 3 @ 25:12 Bob Richards)) "Most of the time now it's sort of a greenish gray color. So, you just cannot see down as far as you used to. It has lost some of the sparkle and some of the extreme sharpness that it used to have." ((S/U tape 3 @ 16:27 Shelly Purdy)) "So why should you even care about the clarity in Lake Tahoe? Besides the fact that most people think blue water is prettier than green water, declining water clarity also has economic impacts you might not have thought about." ((TRACK 3)) Lake Tahoe's water is directly tied to tourism, recreation, and even property values. The lake also provides much of the drinking water for the Truckee Meadows. If the water quality goes down it will cost a lot more to filter it, just so that we can drink it. I'm Shelly Purdy for News Channel 8. ((Anchor tag/Full Screen)) If you would like more information about water clarity and its effects, visit our website at and click on the Lake Tahoe Report icon. Now that Shelly has outline the major problem facing Lake Tahoe, in next week's Lake Tahoe Report segment she'll take a look at efforts underway to save the lake.

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