This map tool is provided for general reference only and is not intended to provide a final determination whether a specific property may be subject to Tier 3 of the On-Site Wastewater Treatment System policy. Additional site-specific information may be required.

If no nitrogen- or pathogen-impaired waters listed in Attachment 2 of the policy are identified within 2000 feet of an address, it is likely that a property owner will only need consult their local permitting agency for what requirements they have to meet if their system fails, or if they plan to upgrade or replace their system.

If nitrogen- or pathogen-impaired waters listed in Attachment 2 of the policy are identified within 2000 feet of an address, there is a possibility that any existing, new or replaced onsite system falls in the Tier 3 category. However, due to data limitations, property owners are strongly advised to conduct further investigation with the help of their local agencies and/or Regional Water Quality Control Board and/or State Water Resources Control Board to determine whether they fall into the Tier 3 category before making any changes to their onsite system.

Condition	Condition Description	Timeline for Compliance
A	A TMDL, or local agency special provisions, have been adopted for the water body listed in Attachment 2 of the Policy that includes onsite systems as a source of pollution. The TMDL's implementation program or local agency special provisions will establish which onsite systems are included and what is required for each existing, new and replaced system. NOTE: If a TMDL exists for a water body listed as impaired for nitrogen and/or pathogens and does not include onsite systems as a source of pollution, then system owners do not need to comply with the supplemental treatment requirements.	Will be specified in the TMDL implementation program or the local agency special provisions.
B	The onsite system was installed prior to the date the water body is listed on Attachment 2 of the Policy, the system is within 600 feet of a water body listed for pathogens or nitrates in Attachment 2 of the Policy, and neither a TMDL nor local agency special provisions for the water body are adopted within two years after the date specified in Attachment 2.	Upon issuance of a waiver or waste discharge requirements by the Regional Water Board.
C	A new or replaced onsite system will be permitted within 600 feet of a water body listed in Attachment 2 of the Policy, and there are no TMDL or local agency special provisions.	Supplemental treatment must be added at the time of permit issuance.
D	A TMDL has not been adopted for a water body listed as impaired by pathogens or nitrogen pursuant to Section 303(d) of the Clean Water Act, and the water body is not included in Attachment 2 of the Policy.	No requirements unless established by a future TMDL.

The distances provided by this map tool are subject to the limitations of the underlying data. To accurately interpret this map, it is very important to understand these limits.

The nitrogen- and pathogen-impaired water bodies were mapped using the U.S. Geological Survey's medium- and high-resolution National Hydrography Dataset (NHD). The medium resolution NHD is mapped at 1:100000 scale and has a horizontal accuracy of +/- 167 feet. The high-resolution NHD is mapped at 1:24000 scale and has a horizontal accuracy of +/- 41 feet.

This map also uses a third-party address-locating service (also known as a "geocoding service") which translates addresses to points on a map. This process, which does not match the address to the parcel, is only as accurate as the underlying street data, which varies depending on the area.

It is also important to note that the OWTS policy requirements apply to the distance between the impaired water and the location of the septic system, which usually differs from the point plotted by the address search.

Given these limitations, property owners whose properties fall within 2000 feet of a nitrogen- or pathogen-impaired water body listed in Attachment 2 of the OWTS policy are strongly advised to conduct further investigation to determine whether their property may be affected by the OWTS policy requirements.