Coverage – Any impervious surface that impedes plant growth and water infiltration. There are four types of coverage:

1. Hard coverage is a man-made structure either created before February 10, 1972 or created after February 10, 1972 pursuant to TRPA regulations that prevents normal precipitation from directly reaching the surface of the land underlying the structure. Such structures include but are not limited to roofs, decks, streets, sidewalks, driveways, parking lots, and patios.
2. Soft coverage is compacted areas without structures so used before February 10, 1972, for such uses as for the parking of cars and heavy pedestrian traffic that the soil is compacted so as to prevent substantial infiltration. A structure shall not be considered as coverage if it permits at least 75 percent of normal precipitation directly to reach the ground and permits growth of vegetation on the approved species list.
3. Potential Coverage is the amount of coverage allowed as base coverage by TRPA Code of Ordinances but which does not physically exist.
4. Base Allowable Coverage is the amount of coverage that could potentially be placed on a parcel, as defined by either the Bailey or IPES scoring system. 

Excess Coverage Mitigation (ECM) – A TRPA program that requires project proponents to mitigate excess coverage on a parcel that is already covered beyond the amount allowed under the TRPA Regional Plan. Project proponents have several options, including on-site and off-site reduction in coverage and/or an in-lieu mitigation fee.

Land banks – Entities designated by TRPA to facilitate the mitigation of excess land coverage using in-lieu fees collected and to provide transfer mechanisms that enable projects that need more coverage than base allowable. There are two land banks – Nevada Division of State Lands and California Tahoe Conservancy. Their duties, authorities and procedures are located in memorandums of understanding (MOUs).

Local jurisdictions – Cities and counties with permitting authority granted through MOUs with TRPA. Local jurisdictions include City of South Lake Tahoe, Placer County, El Dorado County, Washoe County and Douglas County.

Retire – Retiring existing impervious land coverage is the process of purchasing and restoring a parcel to its natural state, and permanently retiring the coverage. Coverage retirement is done as mitigation for excess coverage or allowing coverage amounts greater than 50% for commercial uses.

Stream Environment Zone – Stream environment zones are land areas owing their physical and biological characteristics to the presence of surface water or shallow groundwater for a significant duration of the growing season in most years. Stream environment zones typically encompass streams, adjacent wetlands, and many of the transitional areas that exist between the boundaries of these waters and adjacent upland landforms and plant communities.

The amount of coverage retired is reported by TRPA annually, using information provided by jurisdictions and land banks. Individual projects paying Excess Coverage Mitigation fees do not need to be reported separately; each jurisdiction should report an aggregated total on the amount of coverage retired to submit to TRPA, along with backup documentation. This information should be entered into the EIP Database once annually by December 31st of each reporting year, not upon each individual transaction. Coverage is considered retired only after restoration has been completed, not when Excess Coverage Mitigation fees are collected by TRPA, the jurisdictions or the land banks. 

There are two basic procedures for reporting accomplishments related to impervious coverage retired:

1.  Permitting authority project verification – Upon completion of a project, the permitting authority documents the amount of coverage retired through a) the transfer retirement ratio or b) excess coverage reduced on-site or off-site, if either apply to the project

TRPA maintains an account file in its Accella system for each parcel in the Tahoe Basin to allow a determination of the current status of a parcel and its future development potential. For each transfer of coverage, specific data is recorded for the sending and receiving site, and additional information is recorded when excess coverage is mitigated. Upon completion of any action taken by TRPA which affects a parcel in regards to coverage, a tracking form is completed and filed in the Accella system (TRPA (a)). During the year, TRPA and jurisdictions with permitting authority granted through an MOU should document information on coverage retired from final security return inspections.

2.   Land bank in-lieu fee mitigation – Land banks document the amount of impervious coverage retired after removing coverage from the land bank inventory or through acquiring coverage using excess mitigation fees.

The jurisdictions collect application and mitigation fees, security deposits and other designated fees in accordance with TRPA fee schedules. All mitigation fees collected by jurisdictions are to be paid to TRPA on a monthly basis. TRPA allocates those fees to the appropriate land bank to carry out mitigation. The jurisdictions adhere to all provisions relating to accounting and tracking of coverage. All project accounting and tracking is completed by the jurisdictions and transmitted to TRPA. Land banks file documents with TRPA when retiring potential coverage to consent to the permanent retirement of potential coverage. Annually, the land banks should prepare and deliver a report to TRPA on all ECM projects performed and fees applied towards each retirement project.