The provisions of C.R.S. 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402; provide the specific statutory authority for adoption of these regulatory amendments. The commission also adopted in compliance with 24-4-103(4) C.R.S. the following statement of basis and purpose.
BASIS AND PURPOSE
Pursuant to the requirements in the Basic Standards (at 31.7(3)), the commission reviewed the status of temporary modifications scheduled to expire before December 31, 2018, to determine whether the temporary modification should be modified, eliminated or extended.
No action: The commission took no action on the following temporary modifications:
Blue River Segment 14: temporary modification of the molybdenum standard. The commission made no change to the expiration date of 12/31/2017 since this issue will be addressed in mid-2017 in a molybdenum-specific hearing.
Yampa River Segments: Seneca-Peabody presented evidence that it is making progress on the plan for eliminating the need for need for the temporary modifications. The commission made no change to the expiration date of the temporary modifications on these segments as the original time allotment was deemed adequate to resolve the uncertainty.
Segment 13b, selenium, (exp 12/31/2018)
Segment 13d, selenium, (exp 12/31/2018)
Segment 13e, selenium, (exp 12/31/2018)
Segment 13g, selenium, (exp 12/31/2018)
Segment 13i, selenium, (exp 12/31/2018)
Extension
Yampa River Segments 13d and 13i: temporary modifications of the iron standards. Seneca-Peabody presented evidence that additional time was necessary to resolve the uncertainty regarding the underlying iron standard. The commission extended the expiration dates of the iron temporary modifications to December 31, 2018.
New Temporary Modifications of the Arsenic Standard:
Consistent with the actions taken in 2013, the commission adopted a temporary modification of the arsenic standard on segments on the following list, with an expiration date of 12/31/2021. At the April 8, 2013 rulemaking, the commission heard testimony that concurred with the finding from December 13, 2011 hearing that an initial reasonable lower limit of treatment technology for arsenic is 3.0 µg/L, pending further investigation by the division, dischargers and stakeholders. The temporary modification was established by the commission to allow for a temporarily less stringent application of the chronic arsenic standard in control requirements for both existing discharges and new or increased discharges.
Upper Colorado Segment 1
Blue River Segment 6a
Blue River Segment 12
Blue River Segment 17
Blue River Segment 18
Eagle River Segment 2
Eagle River Segment 5c
Eagle River Segment 9b
Eagle River Segment 12
Roaring Fork Segment 3c
Roaring Fork Segment 10b
PARTIES TO THE RULEMAKING HEARING
5 CCR 1002-33.57