The Department will use the following decision framework
(Figure 1) to determine if nutrient criteria are attained. The Department may
divide fresh surface waters into segments that are evaluated independently
based on factors such as changes in statutory class or changes in habitat or
waterbody characteristics. Failure to meet any of the response indicators is
sufficient to determine that a waterbody does not attain nutrient criteria. The
Department may decide to not assess a given response indicator where water
conditions would preclude observations (e.g., high turbidity, high color, deep
water).
Figure 1. Decision framework
|
All applicable response indicators meet the values in
Table 1
|
Seasonal geometric mean TP concentration is less than
or equal to the applicable value in Table 1 or an established site-specific
value
AND
If the waterbody has a site-specific value for a
non-TP nutrient established in section 5, the seasonal geometric mean
concentration of the non-TP nutrient is less than or equal to the site-specific
value for the non-TP nutrient
|
Seasonal geometric mean TP concentration is greater
than the applicable value in Table 1 or an established site-specific
value
AND/OR
If the waterbody has a site-specific value for a
non-TP nutrient established in section 5, the seasonal geometric mean
concentration of the non-TP nutrient is greater than the site-specific value
for the non-TP nutrient
|
|
A.
Nutrient Criteria Are
Attained
|
B.
Nutrient Criteria Are Attained
Department may conduct a study to develop a site-specific TP value as described
in section 4(B)
|
|
One or more of the applicable response indicators do
not meet the values in Table 1
|
C.
Does Not Attain Nutrient Criteria
Department may conduct a study to develop a site-specific value for a nutrient
as described in section 4(C)
|
D.
Does Not Attain Nutrient
Criteria
|
A.
Figure
1, A. Nutrient Criteria are Attained
(1) Nutrient criteria are attained if:
(a) the seasonal geometric mean TP
concentration is less than or equal to the applicable value in Table 1 or an
established site-specific value;
(b) the seasonal geometric mean concentration
of a non-TP nutrient is less than or equal to the applicable site-specific
value for a non-TP nutrient established in section 5; and
(c) all applicable response indicators attain
the values for the assigned class in Table 1.
B.
Figure 1, B. Nutrient Criteria Are
Attained
(1) Nutrient criteria are
attained if:
(a) the seasonal geometric mean
TP concentration is greater than the applicable value in Table 1 or an
established site-specific value AND/OR the seasonal geometric mean
concentration of a non-TP nutrient is greater than the applicable site-specific
value for a non-TP nutrient established in section 5; and
(b) all applicable response indicators attain
the values for the assigned class in Table 1.
(2) The Department may conduct or request
further assessment of TP concentrations, other nutrients, and response
indicators to determine if a site-specific TP value is warranted. The study may
be initiated and paid for by the Department and/or another entity. Study plans
must be approved by the Department in coordination with the U.S. Environmental
Protection Agency and meet data requirements in section 4(E). If the Department
determines that a site-specific TP value is warranted, the Department will
propose to amend this Chapter pursuant to section 5.
(a)
Study to establish a
site-specific TP value. The study must include TP and applicable
response indicator data pursuant to Table 1, for at least one year during
critical ambient conditions (e.g., below August median flow
and warm temperatures). Unless otherwise specified by the Department,
monitoring must occur between June 1 and September 30. Monitoring frequency
should be at least monthly for TP and all applicable response indicators. The
Department may require additional years of monitoring and may require
additional habitat and water quality measurements, such as nitrogen
concentrations. Any relevant data meeting the data requirements of section 4.E
and collected within 5 years prior to initiation of the study must be
considered in the study. The study must also evaluate the potential for adverse
impact due to nutrient enrichment of downstream waterbodies or segments. The
study may also investigate if mitigating factor(s) are present that limit algal
and plant growth or chemically or physically bind phosphorus, so it is not
readily available to plants and algae.
(b)
Interpretation of study
results.
(i) Does not attain response
indicator values. The waterbody does not attain nutrient criteria (C or D in
Figure 1) if the Department determines that data collected during the study do
not meet one or more applicable response values in Table 1.
(ii) Site-specific TP value. If a seasonal
geometric mean of TP concentrations in a waterbody exceeds the applicable Table
1 TP value, but the Department determines that the waterbody consistently
attains all applicable response indicator values of the assigned class
(see Table 1) during the study, then the waterbody attains
nutrient criteria and the Department may propose to establish a site-specific
TP value for the waterbody greater than the applicable value in Table 1,
pursuant to section 5. Once established, the Department will substitute and use
the site-specific TP value for decisions regarding attainment of nutrient
criteria for that waterbody. The applicable TP value in Table 1 remains in
effect until a new site-specific value is established. At least one year of
data obtained during critical ambient conditions (e.g., below
August median flow, warm temperatures) must be considered before the Department
will propose to establish a new site-specific TP value. A site-specific TP
value may not be greater than the geometric mean TP concentration measured in
the study.
(c)
Considerations for site-specific TP values. The Department
will consider the following factors when determining whether a site-specific TP
value is appropriate and when deciding whether to propose to establish a
site-specific TP value pursuant to section 5.
(i) The risk of any applicable response
indicators not meeting applicable values. For example, the Department will
consider whether a response indicator is already close to an applicable value
and examine the ambient conditions with respect to applicable response
indicators in previous years.
(ii)
Natural environmental conditions mitigating the impact of phosphorus enrichment
and the risk of those conditions changing. For example, natural limiting
factors can reduce light availability (e.g., shade, turbidity,
water color), bind phosphorus (e.g., clay, dissolved organic
carbon, and aluminum hydroxide can make phosphorus unavailable for plant
growth), or reduce habitat quality for algae (e.g., fine
substrate, high water velocity).
(iii) The risk of adversely affecting
downstream waterbodies by establishing a site-specific TP value greater than
the applicable value in Table 1.
(d)
Qualification. The
Department may propose to reduce an established site-specific TP value if the
Department determines that environmental conditions or mitigating factors have
changed and the established site-specific value is no longer sufficiently
protective or appropriate based on the above considerations. An established
site-specific value may be removed or replaced pursuant to section 5. The new
site-specific TP value must be less than the established site-specific value.
If a site-specific nutrient value is removed from section 5, the applicable
value in Table 1 applies to that site.
C.
Figure 1, C. Does Not Attain
Nutrient Criteria
(1) Nutrient criteria
are not attained if:
(a) the seasonal
geometric mean TP concentration is less than or equal to the applicable value
in Table 1 or an established site-specific value;
(b) the geometric mean concentration of a
non-TP nutrient is less than or equal to the applicable site-specific value for
a non-TP nutrient established in section 5; and
(c) one or more response indicators do not
attain the values for the assigned class in Table 1.
(2) Also, nutrient criteria are not attained
if:
(a) one or more response indicators do not
attain the values for the assigned class in Table 1; and
(b) there is insufficient data to determine
if the seasonal geometric mean TP concentration (or an applicable non-TP
nutrient) is less than or equal to the values assigned in Table 1 or a
site-specific value.
(3)
If the Department determines that a nutrient caused or contributed to
non-attainment of nutrient criteria, then it may conduct a study like the study
outlined in section 4(B)(2) to establish a site-specific value for such
nutrient. The provisions of section 4(B)(2) would apply to the Department's
assessment of and decision to propose to establish any such site--specific
nutrient value. If such a site-specific nutrient value is established pursuant
to section 5, it would be included in the nutrient criteria for that waterbody
to achieve attainment of water quality standards.
D.
Figure 1, D. Does Not Attain
Nutrient Criteria
(1) Nutrient criteria
are not attained if:
(a) the seasonal
geometric mean TP concentration is greater than the applicable value from Table
1 or an established site-specific value, or the seasonal geometric mean
concentration of a non-TP nutrient is greater than the applicable site-specific
value for a non-TP nutrient established in section 5; and
(b) one or more response indicators in a
waterbody do not attain the values for the assigned class in Table 1 OR there
is insufficient data to determine that one or more of the response indicators
in a waterbody attain the values of the assigned class in Tables 1.
NOTE: Listing water bodies that do not attain nutrient
criteria (identified in section 4(C) or 4(D) of this Chapter). The
Department will follow the listing methodology in the biennial Integrated Water
Quality Monitoring and Assessment Report (Federal Clean Water Act §§
303(d), 305(b), and 314). The listing methodology is available for review
during the public comment period for each report. When phosphorus enrichment is
accompanied by another factor that contributes to non-attainment, the
Department may list more than one cause of impairment.
E.
Data
requirements
(1) Responsibility for
sampling. The Department, or its agents, generally conducts sampling for the
purpose of making decisions on the attainment of designated uses or maintenance
of existing uses. The Department may request or require an applicant for, or
holder of, a waste discharge license, water quality certification, or other
Department-issued license to conduct sampling of effluent and ambient
conditions. The Department's request or requirement for monitoring and sampling
may be based on the classification goal of the water, attainment status,
existing water quality information, past performance of existing controls for
point and nonpoint sources of pollution, the nature, magnitude, and variability
of the activity relative to the affected water, or other factors at the
discretion of the Department. Sampling must be performed by qualified persons
based on considerations such as relevant education, training, and experience.
Outside entities must submit sampling plans to the Department for review and
acceptance by the Department before collecting data.
NOTE: Data collection. All data collection must
follow protocols and quality assurance procedures approved by the
Department.
(2) Sampling.
The Department will use best professional judgment to determine the amount of
nutrient and response indicator data necessary to meet data quality objectives
to make an attainment decision. The Department will, in its discretion,
determine the appropriate number, timing, and frequency of samples required to
evaluate attainment of the nutrient criteria for a particular waterbody by
considering relevant factors and information, including without limitation, the
type of waterbody being sampled, knowledge of past water quality, applicability
of response indicators, and potential variation in response indicator
values.
(3) Data quality. The
Department will evaluate the quality of data to ensure that data are
representative of ambient conditions and are suitable for analysis. Data from
outside sources may be used if the Department determines them to be of
sufficient quantity and quality based on consideration of factors such as the
training and expertise of the people that collected the data, standard
operating procedures, quality assurance and quality control practices, and
other documentation. The Department may require additional sampling if it
determines that data from an outside source is insufficient.
F.
Established site-specific
nutrient values. If the Department determines that a site-specific value
for TP or another nutrient is warranted, the Department will propose to amend
this Chapter to add the site-specific value to section 5 through agency
rulemaking. The amended Chapter will be submitted to the U.S. Environmental
Protection Agency (EPA) for approval. The amended Chapter will become effective
and the site-specific nutrient value will be established, subsequent to EPA
approval.
