2008 Rulemaking Hearing

The Chatfield Control Regulation (Regulation 73) is scheduled for a Rulemaking Hearing before the WQCC in November 2008.  The WQCD has identified issues with the phosphorus standard, chlorophyll target, phosphorus load estimation, and the phosphorus TMAL.  The WQCD also recommends opening Regulation 38 (South Platte River basin standards and classifications) for concurrent changes.

• WQCD issues from 2007 Triennial Review
• Authority response from 2007 Triennial Review
• Discussion schedule and topics
• Authority issues and concerns  

WQCD Staff Concerns (Memo Jim Saunders)

1. The phosphorus standard has been exceeded in 5 of the last 6 years, while the chlorophyll target has not. The incongruity suggests that the linkage between chlorophyll and phosphorus, which is a critical underpinning of the TMAL, should be revisited. Chlorophyll is especially relevant insofar as the Division intends to emphasize chlorophyll in the development of nutrient criteria for lakes.
   
2. In the process of reviewing recent phosphorus data from the reservoir, it became apparent that greater clarity is needed in describing the protocol for computing the average phosphorus concentration.
   
3. This is an opportunity to revisit the basis for the TMAL and to address one of the recommendations in the Stednick report concerning update of modeling provisions.
4. The phosphorus load estimation procedures, which play a key role in determining the TMAL, should be re-evaluated. Recently, a similar effort was undertaken successfully with Cherry Creek Reservoir, and the Division would like to employ consistent procedures to improve the basis for the TMAL in Chatfield

 

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