practices (BMPs) for improving water quality [41]. In a watershed where fecal
contamination sources are not clearly known, MST can often identify the source of
fecal bacteria. Options for bacterial source identification include determining
whether the source is human or non-human, or identifying the non-human species
(e.g., cow, dog, deer), and then eliminating insignificant sources of fecal bacteria.
Developing accurate and implementable TMDLs relies on identifying and appropriately characterizing the pollutant sources causing the impairment [42].
Regular monitoring for FIB and using MST can often assist in determining
trends and sources of impairments related to nutrients and aquatic life use [41]. In
Virginia, 30 % of assessed rivers/streams, 43 % of assessed lake areas, and 92 % of
assessed estuarine waters are listed as impaired for aquatic life use due to nutrient
enrichment and low dissolved oxygen [40]. Nutrient enrichment or eutrophication
contributes to the formation of oxygen-depleting algae blooms and hypoxia. Low
dissolved oxygen is a common impairment cause in Virginia, impacting lakes and
estuarine waters, especially the Chesapeake Bay.
In addition to the assessment process, MST can also support pollutant source
allocation analysis and the development of a TMDL implementation plan
[41]. More specifically, MST can help identify the sources that contribute to the
observed impairment, determine which sources are likely dominant in the watershed of interest, and focus management actions through targeting implementation
and identifying controls that are appropriate and relevant to the identified sources.
MST can also be useful for obtaining stakeholder buy-in for supporting watershed
management activities during TMDL implementation in locales with contentious
issues. MST can provide more acceptable or concrete evidence to stakeholders
regarding their role in bacterial inputs and resulting impairments, often facilitating
acceptance of responsibility and subsequent implementation of BMPs.
Many of the TMDLs in Virginia and the US mid-Atlantic region have been
developed as part of the initiative to improve water quality of the Chesapeake Bay,
the largest estuary in the USA. The Chesapeake Bay TMDL program is the most
prominent in the USA to date, and about 90 % of the estuarine water category in
Virginia represents waters of the Chesapeake Bay [43]. These estuarine waters have
additional uses underneath the umbrella of “aquatic life use.” These “sub-uses” are
specific to the diverse assemblages of aquatic organisms that live in the Bay. One
special sub-use is the shallow-water submerged aquatic vegetation (SAV) use. As
the name suggests, this use supports conditions favorable to the growth and survival
of submerged vegetation. SAV provides critical nursery habitat for blue crabs and
fishes. Reduced water clarity due to shoreline erosion and suspended sediments is
the major cause of impairment for the shallow-water SAV use. Currently, 53 % of
SAV use in the entire Bay system is impaired. MST has been useful in identifying
sources of pollution that impact SAV use [44].
Microbial Source Tracking: Advances in Research and a Guide to Application
271
contamination sources are not clearly known, MST can often identify the source of
fecal bacteria. Options for bacterial source identification include determining
whether the source is human or non-human, or identifying the non-human species
(e.g., cow, dog, deer), and then eliminating insignificant sources of fecal bacteria.
Developing accurate and implementable TMDLs relies on identifying and appropriately characterizing the pollutant sources causing the impairment [42].
Regular monitoring for FIB and using MST can often assist in determining
trends and sources of impairments related to nutrients and aquatic life use [41]. In
Virginia, 30 % of assessed rivers/streams, 43 % of assessed lake areas, and 92 % of
assessed estuarine waters are listed as impaired for aquatic life use due to nutrient
enrichment and low dissolved oxygen [40]. Nutrient enrichment or eutrophication
contributes to the formation of oxygen-depleting algae blooms and hypoxia. Low
dissolved oxygen is a common impairment cause in Virginia, impacting lakes and
estuarine waters, especially the Chesapeake Bay.
In addition to the assessment process, MST can also support pollutant source
allocation analysis and the development of a TMDL implementation plan
[41]. More specifically, MST can help identify the sources that contribute to the
observed impairment, determine which sources are likely dominant in the watershed of interest, and focus management actions through targeting implementation
and identifying controls that are appropriate and relevant to the identified sources.
MST can also be useful for obtaining stakeholder buy-in for supporting watershed
management activities during TMDL implementation in locales with contentious
issues. MST can provide more acceptable or concrete evidence to stakeholders
regarding their role in bacterial inputs and resulting impairments, often facilitating
acceptance of responsibility and subsequent implementation of BMPs.
Many of the TMDLs in Virginia and the US mid-Atlantic region have been
developed as part of the initiative to improve water quality of the Chesapeake Bay,
the largest estuary in the USA. The Chesapeake Bay TMDL program is the most
prominent in the USA to date, and about 90 % of the estuarine water category in
Virginia represents waters of the Chesapeake Bay [43]. These estuarine waters have
additional uses underneath the umbrella of “aquatic life use.” These “sub-uses” are
specific to the diverse assemblages of aquatic organisms that live in the Bay. One
special sub-use is the shallow-water submerged aquatic vegetation (SAV) use. As
the name suggests, this use supports conditions favorable to the growth and survival
of submerged vegetation. SAV provides critical nursery habitat for blue crabs and
fishes. Reduced water clarity due to shoreline erosion and suspended sediments is
the major cause of impairment for the shallow-water SAV use. Currently, 53 % of
SAV use in the entire Bay system is impaired. MST has been useful in identifying
sources of pollution that impact SAV use [44].
Microbial Source Tracking: Advances in Research and a Guide to Application
271