.. rients into the lake. The adversity varies with the varying land disturbances. Air quality controls obviously aid in the fight to protect the lake, but more emphasis is needs to be geared towards wetland preservation and land controls and watershed management. Water Inflow and Algae Growth Waterflow into lake Tahoe is the number one contributor to the decline in clarity because of all the elements combining to impact the quality of input into the lake.
Lake Tahoe is filled by 63 streams and thus creating a web linking the wetlands, groundwater, streams and lake ecosystems. Displayed earlier is the importance of each ecosystem to each other in creating a balance in the lake. The uniqueness of Lake Tahoe is its color and clarity, but, also in its phosphorous quality, nitrogen limited system. “In most productive lakes the levels of nitrogen and phosphorous are in the low parts per million range. In Lake Tahoe there are only a few parts per billion of these same elements, and the ratio of nitrogen to phosphorous has been well below the 10 to 1 ratio required by most plants.” (3:50, 8:1322) However, over the last decade the ratio is beginning to change causing changes defined as early “eutrophication”.
Research has shown that streams do carry stimulating nutrients into the lake enhancing algae growth. The streams thus cause nutrient loading of the lake and the wetlands are what helps reduce this process. Land use is strongly tied to the watershed characteristics and whether the watershed will be nutrient high. In watershed analysis of Trout Creek and Blackwood Creek nitrite and nitrate concentrations have been declining over the last 10 years, or more, where the increases were caused from sewage and logging consecutively, up to 20 years ago. This decline and hence recovery may be partly due to the rapid vegetation re-growth after the logging activities.
But today’s destruction of land is extensive with the road cuts and developments. “Watershed recovery times at Tahoe may take at least 10-20 years, whereas disturbances such as run-off enhancement from increased impervious surface area may be permanently enhance the nutrient loading of the streams and in turn the lake.(10:87)” The cycling of nutrients, as seen in figure four, show the delicate balance and the nutrient capacity will depend upon streams inflow, air quality sources, and sedimentary soil controls. The nutrient inflow or loading of the lake water directly results in creased algae or Planktonic algae, which there are two kinds: free-floating algae, and attached. Worse case scenario of high nutrient loading would be “the suspended algae cloud the lake water and when algal cells die and decay, they often reduce the dissolved oxygen levels to the point where aquatic organisms can no longer survive in the deep waters(5:6).” Now, Tahoe is not there, yet, but there is evidence of decreasing clarity, increasing planktonic, attached and free-floating algae. Algae has been found to be greatest where there is greater development, logically the run-off. of fertilizers from lawns and golf courses, and other land disruptions discussed prior.
In addition the highest production of algae occurs when Tahoe has had an extremely high precipitation season. “The El Nio event of 1983 modified weather to produce heavy precipitation resulting in high levels of surface runoff from the disturbed watershed as well as wind-mixing of stored nutrients (5:7).” These conditions tend to provide the nitrogen needed for the “lighted zone,” of the lake water, to produce record crops of algae. Lake Tahoe has been studied and compared to other Western Lakes, such as, Castle Lake and Pyramid Lake, and arguments have been made that the climatic variations affect all the lakes of the west equally, increasing fertility to the same degree. However, Castle Lake has not shown the same fertility, despite same data collection methods.(3) Which demonstrates Lake Tahoe’s problems are self-inflicted. Steps Towards Protection The construction and building boom has monopolized the Tahoe basin and has helped to wreak havoc on the precious balance in the lake. Today environmentalist, scientists, and concerned citizens have begun to understand and change the way we treat the environment and the lake, thus protecting the lake quality.
Gone unchecked the lake conditions will worsen. Even in the 1960’s, in May and June, large crops of attached algae died and released from their sites (along piers and shore rocks), coating the beaches and marinas with a brown, slimy, smelly material that decays and eventually returns as bacteria and nutrients to the lake through wave action (3:47). This picture is not what most people envision when picturing the sapphire blue waters of the lake. Obvious changes and the educated observations have led to great concerns over the quality of the lake. Many changes are not as visible but if left alone will quickly become visible, thus destroying the ecosystem of the basin. As mentioned, the lake is the center of many factions of political control.
The Tahoe Regional Planning Agency (TRPA) has been a strong facilitator of the needs for controls, there is little evidence to show they have made any tremendous impact needed to reverse the trends of fertility in the Lake. TRPA has put forth pollution control measures called “Best Management Practices or BMP’s.” The program requires new projects to implement the BMP’s required paved driveways, which at first seems like a contradiction to the research, however, if we compare a graded, disturbed, un-paved surface with a properly paved surface, the un-paved has nothing to hold the soil in place, washing the unnecessary sediment into the lake. Other BMPs, include but are not limited to, revegetation programs, retaining structures, and slope stabilization. To protect the lake all parties involved need to unify the conservation efforts and develop an organized protection and planning bureau or assembly, sponsored with governmental support, above and beyond the Tahoe Regional Planning Agency and Lake Tahoe Interagency Monitoring Program. The current agencies, and committees have taken positive steps to protect the area which includes: * slow releasing or no chemical fertilizers on lawns and golf courses.
* ski slopes are no longer allowed to use ammonium nitrate to help make snow. * California passed a 85 million dollar bond in 1982 to buy-up sensitive lands, potentially endangering the lake, now are protected. * Nevada passed a similar 30 million dollar buy-up bond in 1986. * The afore-mentioned mentioned BMP’s. Without these positive approaches, the dedication of the University of Davis, Researchers and Scientists, Tahoe Regional Planning Agency, and other groups of concerned organizations, Tahoe would be unclear and green today.
The general public can take measures by treating our delicate ecosystems with respect and becoming educated on our delicate balances. Steps could include: * Bike more or walk- save our air quality. * Maintain cars properly and up to codes. * Don’t Drip. Leaky facets waste 9 liters of water per minute. * Don’t pour toxins into the drainage system (paint, gases, fertilizers, etc.) * Recycle * Influence your work place to take steps in being Earth conscious.
For heavens’ sake even the cartoons are teaching our children to be earth aware with “Captain Planet, he’s our hero, taking pollution down to zero..,” teaching children to reduce, reuse, and recycle, and to fight the bad-guys who pollute our earth’s ecosystems. All adults can be Captain Planets and protect our world. Bibliography 1) Richards, Bob. Personal Phone Interviews, FAX. 24 Feb.
1997, 16 Mar 1997. 2) Gabler, Robert, Sager,Robert, and Wise, Daniel Essentials of Physical Geography. 5th ed. Orlando:Saunders College Publishing,1997. 3) Goldman, Charles R., Richards, Robert. The Urbanization of the Lake Tahoe Basin: A Microcosm for the Study of Environmental Change with Continuing Development. Proceedings, State of the Sierra Symposium 1985-86, Pub.
#177. California:University of Davis, 1986 4) Tahoe Research Group, State Natural Resources. Lake Tahoe Facts”, “Ten Most Frequently Asked Questions. Internet address:WWW.Ceres, 15 April 1997. 5) Goldman, Charles R., Byron, Earl R. Changing Water Quality at Lake Tahoe: the First Five Years of the Lake Tahoe Interagency Monitoring Program. The California State Water Resources Control Board.
California:University of Davis, Institute of Ecology, Tahoe Research Group, 1987. 6) Sheaffer, John R., Stevens, Leonard A., Future Water, An Exciting Solution to America’s Most Serious Resource Crisis. New York: William Morrow and Company, Inc., 1983. 7) Reuter, J.E., et al. University Contribution to Lake and Watershed Management: Case Studies From the Western United States–Lake Tahoe and Pyramid Lake.
Watershed ’96 A National Conference on Watershed Management. Maryland:Baltimore, Water Environment Federation, 12 June 1996. ISBN: 1-57278-028-2. 8) Goldman, Charles R. Primary Productivity, Nutrients, and Transparency During the Early Onset of Eutrophication.
American Society of Limnology and Oceanography, Inc. 33(6, part1),1321-1333. 1988. 9) Goldman, Charles R., Jassby Alan D., de Amezaga, Evelyne. Forest Fires, Atmospheric Deposition and Primary Productivity at Lake Tahoe, California-Nevada. Verhandlungen-Proceedings-Travaux of the International Association for Theoretical and Applied Limnology, Congress in Munich.
Iss 24, 499-503. Stuttgart, Germany, 1990. 10) Byron, Earl r., Goldman, Charles R., “Land-Use and Water Quality in Tributary Streams of Lake Tahoe, California-Nevada”. Journal of Environmental Quality Vol. 18,no.1, (Jan-Mar 1989):84-88.
11) Bowman, Chris. “Clinton Seeks Summit on Lake Tahoe Pollution” The Sacramento Bee 26 October 1996:B1 12) Bowman, Chris, Hoge, Patrick. “Runoff, Air Pollution Cloud Waters of Crystal-Clear Lake” The Sacramento Bee 8 December 1996:A28 13) Associated Press. “Team Seeks Clues to Cloudy Lake Tahoe Water” The Sacramento Bee 16 October 1995:SUPCAL. 14) Malley, George. Personal Interview.
15 April, 5 May 1997 MAPS AND GRAPHS — REFERENCES Figure One, Tahoe Region Map: AAA Travel Book. 1997 ed. Figure Two, Secchi Depth Chart: Goldman, Charles R. Primary Productivity, Nutrients, and Transparency During the Early Onset of Eutrophication. American Society of Limnology and Oceanography, Inc. 33(6, part1),Pg.
1329. 1988. Figure Three, Population Growth Chart: Goldman, Charles R., Richards, Robert. The Urbanization of the Lake Tahoe Basin: A Microcosm for the Study of Environmental Change with Continuing Development. Proceedings, State of the Sierra Symposium 1985-86, Pub. #177. California:University of Davis, Pg.
43. 1986. Figure Four, Water Cycle Chart: Goldman, Charles R., Richards, Robert. The Urbanization of the Lake Tahoe Basin: A Microcosm for the Study of Environmental Change with Continuing Development. Proceedings, State of the Sierra Symposium 1985-86, Pub.
#177. California:University of Davis, Pg. 43. 1986.