COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT
WATER QUALITY CONTROL COMMISSION
5 CCR 1002-73
REGULATION NO.  73
CHATFIELD RESERVOIR CONTROL REGULATION
73.0	CHATFIELD RESERVOIR CONTROL REGULATION
73.1	AUTHORITY
The Water Quality Control Commission is authorized by section 25‑8‑205, C.R.S. to promulgate control regulations to describe limitations for the extent of specifically identified pollutants that any person may discharge into any specified class of state waters.
…
73.3	TOTAL MAXIMUM ANNUAL LOAD ALLOCATION FOR TOTAL PHOSPHORUS LOADING AND EFFLUENT LIMITATIONS
1.	TOTAL MAXIMUM ANNUAL LOAD ALLOCATION FOR TOTAL PHOSPHORUS LOADING
a.	A new total maximum annual load (TMAL) for phosphorus of 19,600 lbs/y under a median inflow of 100,860 AF/y has been identified to attain the water quality standards for 10 µg/l chlorophyll a and 0.030 mg/L total phosphorus, as described in Regulation No.38.
 i.	Revised allocations of that load will be developed to complete revisions to the TMAL.
ii.	Activities necessary to reduce the actual phosphorus loads to an amount no greater than the TMAL shall be implemented.
iii.	The activities to support revisions to allocations of the allowable load are identified below. The Authority shall implement these activities, as allowed by applicable funding levels, for review by the Division and Commission at the next triennial review. Results from the Authority’s implementation of this control regulation and the load allocation development tasks listed below may suggest redefining and reprioritizing activities. The Authority shall submit any such proposed revisions with proposed priorities for review and approval by the Division, annually, in their annual report to the Commission due May 15 of each year. The activities shall include, but are not limited to the following items:
A.	Partition allowable load between the two main basins (South Platte and Plum Creek);
B.	Determine allocation of loads within each basin;
C.	Revise wasteload allocations, as appropriate; and
D.	Update definitions and regulation language to support TMAL revisions.
iv.	 Attainment of the TMAL may require progressive development of point source and nonpoint controls.
v.	The following provisions of this control regulation along with the waste load and load allocations remain in effect until revisions have been adopted to meet the new TMAL.
b.	The total phosphorus allocations by watersheds are distributed among sources as follows:

Allocation Type	Total Phosphorus
Pounds/Year	
Total Maximum Annual Load (TMAL) =	59,000 @ 261,000 ac-ft/year	
Chatfield Watershed	40,894	
	Reservoir Base-Load	13,400	
	Background	19,961	
	Wasteload Allocation (point sources)	7,5331	
Upper South Platte River Watershed	17,9302	
	Reservoir Base-Load	6,000	
	Background	11,842	
	Summit County Wasteload Allocation	88	
Total	58,8243	
1	Point source discharge permit holders and regulated stormwater permittees who are in compliance with their permit limits and terms for a constituent will not have those limits or terms modified prior to any future adjustment of classifications or standards by the Commission to the extent any observed water quality standards exceedances are attributable to other factors, such as wildfires that are beyond the control of the permit holders.
2	Loadings from the Upper South Platte River watershed include all point sources upstream of the Strontia Springs Reservoir outfall, including 88 pounds of phosphorus per year from wastewater originating in Summit County and discharged directly into the Roberts Tunnel, and all nonpoint sources above the Strontia Springs Reservoir outfall.
3.	While the TMAL total phosphorus poundage allocation formula remains unchanged, the amount of total phosphorus assigned to the Chatfield Watershed is reduced because of approved nonpoint source to point source trades.
2.	EFFLUENT LIMITATIONS AND POINT SOURCE WASTELOAD ALLOCATIONS
a.	The Division shall not issue discharge permits (pursuant to Regulation #61) or notices of authorizations for use of reclaimed water (pursuant to Regulation #84) to any wastewater facilities and industrial process wastewater sources that allow effluent limitations exceeding their total phosphorus allocation, unless such exceedances consist solely of phosphorus pounds awarded from the Reserve Pool, or that are authorized through the Trading Program or by Temporary Transfers.  However, in no event shall these allocations be construed to allow discharges in violation of the requirements of section 73.3.1, subject to approved trades pursuant to section 73.3.2.
b.	No municipal, domestic, or industrial wastewater discharge in the Chatfield Watershed shall exceed 1.0 mg/l total phosphorus as a 30‑day average concentration, except as provided under section 73.3(2)(f)
c.	The allowed annual wasteload of point source phosphorus in the Chatfield Watershed is limited to 7,533 lbs/yr, allocated among the dischargers as follows, except as provided in sections 73.3(2)(e),(g),(h), and (i):

Facility	Pounds Per Year	
Plum Creek Wastewater Authority	4,256	
Lockheed Martin Astronautics	1,005	
Roxborough Park Metro District	1,218	
Perry Park Water & San. District‑Waucondah	365	
Perry Park Water & San. District‑Sageport	73	
Town of Larkspur	231	
Louviers Mutual Service Company	122	
Sacred Heart Retreat	151	
Jackson Creek Ranch	502	
Ponderosa Retreat Center	752	
Centennial Water and Sanitation District	502	
Reserve/Emergency Pool	 73	
Total Point Source Phosphorus Wasteload =	7,533	
1	A five-year Total Phosphorus Allocation (2010) of 15 pounds for inclusion in the Sacred Heart discharge permit; Obtained from the Reserve/Emergency Pool.
2	These entities received point source allocations through trades pursuant to the Authority Trading Guidelines.
d.	Phosphorus effluent limits for site approvals and discharge permits in the Chatfield Watershed shall be based on total phosphorus effluent quality of 1.0 mg/l for a 30‑day average at the design capacity of the wastewater facility, except as provided in section 73.3(2)(f), and the annual wasteload allocation specified in this section, except as provided in 73.3(2)(e)(g)(h) and (i).  A wastewater treatment facility may need to adjust operations for periods of time sufficient to meet the annual phosphorus poundage allocation by producing effluent total phosphorus concentrations below 1.0 mg/l.
e.	Point source dischargers may apply to the Chatfield Watershed Authority and the Division for phosphorus trade credits, which allow corresponding increases to a discharger’s total phosphorus wasteload allocation.  Phosphorus trade credits for point sources shall be based upon reductions of phosphorus from nonpoint sources.  The amount of point source trade credit shall be based upon one pound of credit for two pounds of nonpoint source reduction, unless water quality data substantiates greater phosphorus removals, in which case one pound of trade credit may be established by fewer than two pounds of nonpoint source reduction, on a site-specific basis.  The Chatfield Watershed Authority shall review the application for trade credits in coordination with the Division.  The Chatfield Watershed Authority shall take action by approving, conditionally approving, or denying the trade credits, and forward its decision to the Division.  Thereafter, the Division shall consider the Authority’s decision and render the Division’s final decision on the trade credits.  Trade credits shall be incorporated into discharge permits by the Division, as appropriate, and incorporated as proposed amendments to the phosphorus allocation at the next triennial review or rulemaking hearing for this regulation.
f.	Point sources may discharge a total phosphorus concentration of greater than 1.0 mg/l if an agreement has been made with an alternative point source discharger for equal phosphorus reduction.  The agreement for alternative treatment must be executed by the owners of both facilities, and the agreement must describe estimated changes in average wastewater flows and performance in treatment of phosphorus.  The wastewater facility that agrees to provide the equivalent phosphorus poundage reduction must demonstrate that it is achieving a total phosphorus effluent concentration of less than 1.0 mg/l for a period of time sufficient to remove the equivalent phosphorus load by which the wastewater treatment facility is exceeding its wasteload allocation.  The Chatfield Watershed Authority shall review applications for alternative treatment arrangements in coordination with the Division.  The Chatfield Watershed Authority shall take action by approving, conditionally approving, or denying the alternative treatment arrangements, and forward its decision to the Division.  Thereafter, the Division shall consider the Authority’s decision and render the Division’s final decision on the alternative treatment arrangements.  Alternative treatment arrangements, including provisions for equivalent phosphorus reductions shall be incorporated as permit conditions into both discharge permits, as appropriate.
g.	Point source wastewater dischargers shall apply to the Chatfield Watershed Authority and the Division for transfers of all or part of one point source discharger’s total phosphorus allocation to another point source wastewater discharger.  Both dischargers must jointly apply for such transfers.  Applications for transfer must include an agreement executed by the owners of the facilities specifying changes in average wastewater flows and performance in treatment of total phosphorus.  The Chatfield Watershed Authority shall review phosphorus transfer proposals in coordination with the Division.  The Chatfield Watershed Authority shall take action by approving, conditionally approving, or denying the phosphorus transfer, and forward its decision to the Division.  Thereafter, the Division shall consider the Authority’s decision and render the Division’s final decision on the phosphorus transfer.  The Division shall incorporate approvals in both discharge permits, if these transfers are not otherwise accounted for by the Division.
h.	Point source wastewater dischargers may apply to the Chatfield Watershed Authority and the Division for allocations of total phosphorus pounds from the reserve/emergency pool, to be applied to the dischargers total phosphorus wasteload allocation.  Applications for total phosphorus pounds from the reserve/emergency pool must specify the number of pounds desired from the pool.  The Chatfield Watershed Authority shall review the application for allocations of phosphorus from the reserve/emergency pool in coordination with the Division.  The Chatfield Watershed Authority shall take action by approving, conditionally approving, or denying allocations from the reserve/emergency pool, and forward its decision to the Division.  Thereafter, the Division shall consider the Authority’s decision and render the Division’s final decision on an allocation from the reserve/emergency pool.  Approved allocations of phosphorus pounds from the reserve/emergency pool shall be incorporated as proposed amendments to the phosphorus wasteload allocation in section 73.3 at the next triennial review or rulemaking hearing of this regulation.
i.	If new point source wastewater facilities are proposed for the Chatfield Watershed, the appropriate entities shall apply to the Chatfield Watershed Authority and the Division for a phosphorus allocation.  Phosphorus allocation pounds for such new point source wastewater dischargers may be derived from:  (1) withdrawals from the reserve/emergency pool pursuant to 73.3(2)(h); (2) nonpoint source to point source trades pursuant to 73.3(2)(e); (3) point source to point source transfers pursuant to 73.3(2)(g); or (4) phosphorus concentration reductions through alternative treatment pursuant to 73.3(2)(f).  Applications shall specify the number of desired total phosphorus pounds and how the pounds will be derived as specified in 73.3(2)(i).  The Chatfield Watershed Authority shall review the applications for phosphorus allocations in coordination with the Division.  The Chatfield Watershed Authority shall take action by approving, conditionally approving, or denying the new phosphorus allocations, and forward its decision to the Division.  Thereafter, the Division shall consider the Authority’s decision and render the Division’s final decision on the new phosphorus allocation.  Allocations for new dischargers shall be incorporated into the new discharge permit by the Division and incorporated as proposed amendments to the phosphorus wasteload allocation in section 73.3 at the next triennial review or rulemaking hearing of this regulation.
j.	The Division shall provide notice of any application for a proposed trade in the Chatfield watershed in the monthly Water Quality Bulletin.  Such notice shall be provided as early in the process as possible but only after the Division has completed its initial review.
k.	Any person adversely affected or aggrieved by a final decision of the Division on trade credits, transfers, or awards of phosphorus pounds from the Reserve Pool pursuant to section 73.3.2 may request an adjudicatory hearing before the Commission pursuant to the requirements and procedures of section 21.4.  5 CCR 1002-21.
…
73.17	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE (NOVEMBER 2008 RULEMAKING HEARING EFFECTIVE MARCH 30, 2009)
Sections 25‑8‑202 and 25‑8‑205, C.R.S., provide the specific statutory authority for adoption of the revisions to this regulation.  The Commission also adopted, in compliance with Section 24‑4-103(4), C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE
The Commission adopted a new total phosphorus allowable load in Section 73.3(1)(a) of this regulation.  Although the allowable load was revised, the total phosphorus allocations were not revised.  Therefore, the Commission included a list of tasks to be completed to support development of revised allocations of the new allowable load in the Control Regulation.  It was the Commission’s intent that until the allocations are revised, the existing nonpoint and point source allocations remain applicable.
Based on information presented by the Division during the July 2007 triennial review hearing, the Commission scheduled a rule-making hearing to consider revisions to the control regulation and to related water quality standards in Regulation #38.  Specifically, the Commission heard evidence that the phosphorus standard in Chatfield Reservoir had been exceeded in 5 of the last 6 years, while the chlorophyll goal was not exceeded.  The Commission agreed that the linkages between in-lake chlorophyll and total phosphorus concentrations and between total phosphorus concentrations and total phosphorus load to the reservoir are critical to the basis of the Control Regulation and TMAL and that these linkages should be reviewed.  
The Commission directed the Division to conduct a limited scope Technical Review of the Control Regulation TMAL and the underlying standard.  The scope of the technical review was limited to the in-lake total phosphorus standard, chlorophyll goal, and the allowable load to attain these.  The scope of the technical review did not include an examination of the allocation of the total phosphorus load.  As part of this Technical Review, the Division provided reports and made monthly presentations to the Chatfield Watershed Authority Technical Review Committee from September 2007 through May 2008.  The reports and presentations provided the basis for the proposal the Commission heard in this rule-making hearing. 
Based on the results of the Technical Review, the Commission adopted revised site-specific standards for total phosphorus and chlorophyll for Chatfield Reservoir in relevant sections of Regulation #38.  These standards are total phosphorus of 0.030 mg/L and chlorophyll a of 10 µg/l measured through the collection of samples that are representative of the mixed layer during summer months (July, August, September) and with a maximum allowable exceedance frequency of once in five years.  As a result of these changes to the site-specific standards, the Commission adopted a new allowable load of total phosphorus of 19,600 lbs/y under a median inflow of 100,860 AF/y in this Control Regulation.  The new allowable load better reflects the linkage between watershed total phosphorus load and the in-lake total phosphorus concentration.
The Commission directed the Division and the Authority to develop new nonpoint source and point source allocations related to the new allowable load for submittal during the next control regulation triennial review.  The Commission acknowledged that progress toward development of the allocations will be contingent on the availability of suitable funding to support completion of the tasks identified in Section 73.3(1)(a).  The Commission also recognized that control regulation definitions and language may need to be revised to support future updates to the TMAL.