As the land has been covered with buildings, roads, parking lots and other types of impervious surfaces, the capacity of many watersheds to perform their natural functions has been seriously impaired. In many locations, development has generated more runoff and erosion than is being absorbed on site or even within the watershed.

In a number of cases, the capacity of watersheds to tolerate these impacts can be improved by removing unneeded development or retiring the development potential of parcels which are currently contributing to water quality problems, or are likely to do so in the future. These sites can then be rehabilitated, and the development rights transferred to less environmentally sensitive land.

In addition, the impacts of existing over-covered parcels and of new projects that must be located in sensitive areas can be mitigated by ensuring that sufficient uncovered or, if necessary, restored land is available to help absorb the impacts, on or off site.

Complementing available private mechanisms, the Conservancy has established a program to meet these needs by dealing with land coverage and other marketable rights.

Initially, the Conservancy identifies individual parcels that are creating water quality problems, or could in the future, and then tries to acquire them, in order to retire the development potential of the site. Such properties range from parcels in a wetland that have dilapidated and unused structures on them, to lots that are eroding or could erode if the soil is disturbed.

After the Conservancy acquires the property, the site is restored as necessary, any unwanted buildings are demolished, unneeded asphalt is removed, the site revegetated, and erosion control measures are installed.

The retirement of the development potential on these properties could generate a wide range of development rights or credits, depending on what existed or was credited to the property at the time of acquisition. Included are such things as existing or potential land coverage rights, as well as mitigation credits for eliminating the property's impact on sensitive land. These rights can then be transferred to other sites or used on-site for new projects.

The Conservancy may also incidentally acquire, as part of its overall acquisition activities, other types of rights, such as those for tourist accommodations, sewer connections, residential units or commercial floor area. Such rights are recognized by various regulatory agencies in the Lake Tahoe Basin, and can be sold or transferred under the proper circumstances.

All such rights and credits acquired by the Conservancy are stored in a "land bank" set up for this purpose. The Conservancy then allocates these credits or rights for both public and private projects, based on projected demand.

Over the life of the program, the Conservancy has authorized the expenditure of more than $4.9 million for the acquisition of more than 1.2 million square feet of coverage. More than 300,000 square feet of old coverage has already been restored.

Credits to mitigate excess coverage have been provided for more than 2200 private and public projects, and coverage and other marketable rights have been transferred to more than 215 private residential and commercial project.

Through these various activities, the Conservancy's land bank also generated more than $2.3 million to be reinvested in further acquisition and restoration activities.