49-234

49-234. Total maximum daily loads;
implementation plans

A. The department shall develop total maximum daily loads for those navigable
waters listed as impaired pursuant to this article and for which total maximum daily
loads are required to be adopted pursuant to 33 United States Code section 1313(d) and
the regulations implementing that statute. The department may estimate total maximum
daily loads for navigable waters not listed as impaired pursuant to this article, for the
purposes of developing information to satisfy the requirements of 33 United States Code
section 1313(d)(3), only after it has developed total maximum daily loads for all
navigable waters identified as impaired pursuant to this article or if necessary to
support permitting of new point source discharges.

B. In developing total maximum daily loads, the department shall use only
statistical and modeling techniques that are properly validated and broadly accepted by
the scientific community. The modeling technique may vary based on the type of water and
the quantity and quality of available data that meets the quality assurance and quality
control requirements of section 49-232. The department may establish the statistical and
modeling techniques in rules adopted pursuant to section 49-232, subsection C.

C. Each total maximum daily load shall:

1. Be based on data and methodologies that comply with section 49-232.

2. Be established at a level that will achieve and maintain compliance with
applicable surface water quality standards.

3. Include a reasonable margin of safety that takes into account any lack of
knowledge concerning the relationship between effluent limitations and water quality.
The margin of safety shall not be used as a substitute for adequate data when developing
the total maximum daily load.

4. Account for seasonal variations that may include setting total maximum daily
loads that apply on a seasonal basis.

D. For each impaired water, the department shall prepare a draft estimate of the
total amount of each pollutant that causes the impairment from all sources and that may
be added to the navigable water while still allowing the navigable water to achieve and
maintain applicable surface water quality standards. In addition, the department shall
determine draft allocations among the contributing sources that are sufficient to achieve
the total loadings. The department shall provide public notice and allow for comment on
each draft estimate and draft allocation and shall prepare written responses to comments
received on the draft estimates and draft allocations. The department shall publish the
determinations of total pollutant loadings that will not result in impairment and the
draft allocations among the contributing sources that are sufficient to achieve the total
loading that it intends to submit initially to the regional administrator, along with a
summary of the responses to comments on the estimated loadings and allocations, in the
Arizona administrative register at least forty-five days before submission of the
loadings and allocations to the regional administrator. Notwithstanding this subsection,
draft allocations shall be submitted to the regional administrator only if that
submission is required by the rules that implement 33 United States Code section 1313(d).

E. Publication of the loadings and allocations in the Arizona administrative
register is an appealable agency action pursuant to title 41, chapter 6, article 10 that
may be appealed by any party that submitted written comments on the estimated loadings
and allocations. If the department receives a notice of appeal of a loading and
allocation pursuant to section 41-1092.03 within forty-five days of the publication of
the loading and allocations in the Arizona administrative register, the department shall
not submit the challenged loading and allocations to the regional administrator until
either the challenge to the loading and allocation is withdrawn or the director has made
a final administrative decision pursuant to section 41-1092.08.

F. The department shall make reasonable and equitable allocations among sources
when developing total maximum daily loads. At a minimum, the department shall consider
the following factors in making allocations:

1. The environmental, economic and technological feasibility of achieving the
allocation.

2. The cost and benefit associated with achieving the allocation.

3. Any pollutant loading reductions that are reasonably expected to be achieved as
a result of other legally required actions or voluntary measures.

G. For each total maximum daily load, the department shall establish a TMDL
implementation plan that explains how the allocations and any reductions in existing
pollutant loadings will be achieved. Any reductions in loadings from nonpoint sources
shall be achieved voluntarily. The department shall provide for public notice and comment
on each TMDL implementation plan. Any sampling or monitoring components of a TMDL
implementation plan shall comply with section 49-232.

H. Each TMDL implementation plan shall provide the time frame in which compliance
with applicable surface water quality standards is expected to be achieved. The plan may
include a phased process with interim targets for load reductions. Longer time frames are
appropriate in situations involving multiple dischargers, technical, legal or economic
barriers to achieving necessary load reductions, scientific uncertainty regarding data
quality or modeling, significant loading from natural sources or significant loading
resulting from discharges or activities that have already ceased.

I. For navigable waters that are impaired due in part to historical factors that
are difficult to address, including contaminated sediments, the department shall consider
those historical factors in determining allocations for existing point source discharges
of the pollutant or pollutants that cause the impairment. In developing total maximum
daily loads for those navigable waters, the department shall use a phased approach in
which expected long-term loading reductions from the historical sources are considered in
establishing short-term allocations for the point sources. While total maximum daily
loads and TMDL implementation plans are being completed, any permits issued for the point
sources are deemed consistent with this article if the permits require reasonable
reductions in the discharges of the pollutants causing the impairment and are not
required to include additional reductions if those reductions would not significantly
contribute to attainment of surface water quality standards.

J. After a total maximum daily load and a TMDL implementation plan have been
adopted for a navigable water, the department shall review the status of the navigable
water at least once every five years to determine if compliance with applicable surface
water quality standards has been achieved. If compliance with applicable surface water
quality standards has not been achieved, the department shall evaluate whether
modification of the total maximum daily load or TMDL implementation plan is required.