Final Water Quality Assessment Guidance Manual
The 2010 federal 305(b)/303(d) assessment methodology guidance remains largely unchanged, however there are changes to state guidance for Virginia that reflect new Water Quality Standards that became effective on February 1, 2010. Most notably, these include changes in many of the criteria for toxics in fish tissue and public water supply as well as revised procedures for assessing water quality in lakes. These changes principally include:
- Inclusion of the use of studies to identify natural conditions for pH and dissolved oxygen in Class VII (swamp waters). The studies allow DEQ to determine specific criteria for those waters and to determine if anthropogenic influences are affecting water quality and causing an impairment or other degradation.
- A revised methodology to assess nutrient influences on man-made lakes and reservoirs identified in 9 VAC-25-260-187 (§187 lakes). In addition to §187 nutrient assessment methodologies, the dissolved oxygen criteria assessment for these lakes has been modified based on stratification, to include dissolved oxygen assessment in the epilimnion only during stratification while assessing the whole water column when deemed not stratified.
- Revisions to many toxic pollutant criteria, primarily related to human health (fish consumption assessments) but also public water supply criteria assessments.
- Inclusion of “nested” waters within an EPA approved watershed TMDL and not requiring nested impairments to obtain a separate TMDL. This nested TMDL concept primarily involves new bacteria impairments associated within existing recreation and shellfish consumption TMDLs but may also include benthic impairments depending upon the specific stressor(s) involved.
A copy of the guidance can be downloaded at this link: Final 2010 WQA Guidance Manual (1.93 MB PDF)
A copy of the comment response can be downloaded at this link: 2010 Comment Response (107 kb PDF)
For a hard copy of the guidance or for more information, please contact Tish Robertson, DEQ Water Quality Assessment Coordinator, using the information below.
Virginia Department of Environmental Quality
Water Quality Assessment Coordinator
P.O. Box 1105
Richmond, Virginia 23218
Telephone (804) 698-4309
FAX (804) 698-4032
Click here for a copy of the Public Notice (16 kb PDF)