EPA Region 10 (EPA) has reviewed the Draft Little Spokane River Dissolved Oxygen and pH TMDL as well as a pre- public notice version. We appreciate the work that has been done to date on monitoring, modeling and development of the TMDL document. The ...↓
1. We recommend that a discussion on pollutant sources be included or summarized in Section 1 Introduction of the TMDL document.
2. We recommend that the TMDL provide more detail regarding the connection between this TMDL and the 2012 Little Spokane River Temperature TMDL.
3. We recommend that the TMDL provide more detail for the public regarding the connection between the dissolved inorganic nitrogen (DIN) and total phosphorus (TP) loading capacity and load/wasteload allocations and the State of Washington's dissolved oxygen (DO) and pH water quality standards.
4. Under the reasonable assurance section, we recommend that the TMDL clarify the estimated timeframe for completing the implementation actions and meeting the water quality standards for the dissolved oxygen and pH impairments, as well as for temperature impairments, as this TMDL is linked to the 2012 Little Spokane River Temperature TMDL, as previously noted. We also recommend including a citation to Washington's legal authority for addressing nonpoint source pollution in this section.
5. We recommend that the TMDL also clearly explain the connection between the TP allocations in this TMDL and the downstream Spokane River/Lake Spokane Dissolved Oxygen TMDL including how the total phosphorus allocations in this TMDL will result in compliance with the downstream total phosphorus target from the Lake Spokane DO TMDL.
6. We recommend that the TMDL provide an explanation regarding the selection of the explicit margin of safety (MOS). For the implicit MOS, we recommend that the TMDL explain why each assumption is conservative with respect to the analysis or alternatively remove the assumption from the MOS section. For example, it would be helpful for Ecology to explain how the use of higher flow analysis would be considered a conservative assumption for an implicit MOS.
7. We recommend that Ecology clearly explain why two different water quality models were used for this TMDL project and how they model outputs work together.
8. We recommend that the TMDL clearly explain how the critical periods for the total phosphorus load allocations were determined and why the load allocations only apply during these critical periods.
9. Please include the following tables of waters and pollutants addressed in the TMDL. In each of these tables, please include the assessment unit, 2012 listing ID, impairment(s), pollutant(s) (for which the TMDL loads are expressed), MOS (if explicit), load allocation, wasteload allocation, and if there is a future reserve:
1) Waters on the 2012 list
2) Unlisted but impaired waters
3) Waters not meeting the criteria for listing, but likely impaired based on available information.
In order to make both Ecology's and EPA's intentions and actions transparent, we request that you identify all waters for which you have prepared TMDLs and that you request EPA approval for those TMDLs. Such submittal and approval will clarify the Clean Water Act status of those waters and the associated allocations.
10.We recommend that each of the separate Appendices to this TMDL document be included as part of the Table of Contents of the TMDL document (the appendices are currently not referenced).
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