69
degrees average
Total Maximum Daily Loads (TMDL'S)
Sediment Infill at Mouth of Rathbun Creek
In the year 2000, the Santa Ana Regional Water Quality Control Board (Regional Board) initiated the TMDL process in Big Bear Lake. Prior to taking this action, the Lake had been placed on the State of California’s “impaired” list for certain metals, nutrients, sediment loading and aquatic plants. This designation triggered implementation of the TMDL effort for Big Bear Lake. Section 303(d) of the federal Clean Water Act requires states to develop TMDL’s for water bodies on their impaired lists.
A TMDL is a written plan describing how a particular water body meets water quality standards. It is a calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards, and an allocation of that amount to the pollutant’s resources. The TMDL process requires that all sources of pollution and all aspects of a watershed’s drainage system be reviewed, not just the pollution coming from a few, readily identifiable sources. A TMDL establishes appropriate levels of pollutant loading for all the various sources.
Understanding the far-reaching effect the TMDL process could have on the entire valley, such as building moratoriums and Lake releases, the District organized a TMDL Work Group to work closely with the Regional Board in addressing this issue. A consultant was retained to coordinate the effort and a cooperative funding mechanism was developed. The District, the City of Big Bear Lake, the County of San Bernardino and the Big Bear Area Regional Wastewater Agency developed a cost-sharing agreement, and various grant applications were submitted to acquire funding for the numerous Lake monitoring activities required in the TMDL process. By the end of 2002, $1,645,000 had been secured in grant funding. In addition to data collection, this funding made it possible for the District to implement an aggressive Eurasian watermilfoil eradication program, using the Sonar herbicide and other herbicides in many areas of the Lake.
A major accomplishment during 2003 was preparation of a report by EIP Associates, Inc. entitled Prehistoric and Historic Environmental Conditions in Bear Valley. This document described the geologic development of Bear Valley and how Big Bear Lake developed physically and biologically. It provided insight into the nutrient loading process, concluding in part that “the internal nutrient loadings are more than sufficient to maintain the reservoir in its current eutrophic state, which is the result of reservoir site location, not land use in the watershed”. This conclusion implies that in-lake controls will likely yield more results in diminishing nutrient levels, than any number of watershed controls. However, a combination of the two will likely be the ultimate solution. In 2004, a Proposition 13 grant proposal for $2,275,000 was approved. This grant provided more than $1.4 million for removal of nutrient-laden sediment from the east end of Big Bear Lake. The remaining funds were used to conduct numerous studies in the watershed and to install a high elevation weather station at Snow Summit ski area..
Much of the monitoring work already indicates that some of the listed impairments will qualify for de-listing as more data is developed. In April 2006, Regional Board adopted the Big Bear Lake Nutrient TMDL, and the District, the County of San Bernardino and the City of Big Bear Lake have already begun working on some of the tasks in the Phase I Implementation Plan. The TMDL Work Group continues to work with the Regional Board on the remaining TMDL issues. Ultimately all stakeholders wish to protect the water quality of Big Bear Lake through the adoption of TMDL's that are attainable, affordable, and based on good science.
Sediment Catchment Basin-
Creating a Lake within a Lake to
reduce sediment and nutrient inflows
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