TULSA — Members of a two-state panel reviewing the validity of phosphorus standards set for Oklahoma's scenic rivers wrangled over definitions and data points while the clocked ticked toward a deadline set for the submission of their final report.

The panel of six — the governors of Arkansas and Oklahoma appointed three each — had hoped to finalize details of a draft final report before adjourning its two-day meeting Friday. Committee members forged a consensus on some fundamental issues before recessing, but they delayed action on some of the more contentious issues.

The committee was formed in 2013 to oversee a stressor-response study authorized by an agreement hammered out by the attorneys general of Oklahoma and Arkansas. That agreement — the second joint statement of principles — was inked in an effort to avoid protracted litigation regarding the validity of Oklahoma's numeric phosphorus standard for its scenic rivers.

The study's primary purpose is to determine "the total phosphorus threshold response level" that produces a "statistically significant shift" in "algal species composition or ... biomass production" that results in "undesirable aesthetic or water quality conditions." The committee's findings are based upon data collected during the course of two years at three dozen sites along scenic rivers and their tributaries.

Committee co-chairman Derek Smithee, water quality division chief for the Oklahoma Water Resources Board, described as an accomplishment the panel's ability to define some terminology and clarify the study's parameters. Smithee said he hopes the committee will "start out talking about what those threshold response levels" of phosphorus are before it begins "to cause nuisance conditions in Oklahoma's scenic rivers."

"Everybody has a different risk tolerance, and that is going to be the tricky part: How much risk should be acceptable or tolerable for our six scenic rivers?" Smithee said. "I am not open to very much risk for our scenic rivers, but some people may be open to a little bit more — that is what we have to fight for."

Committee co-chairman Brian Haggard, a University of Arkansas professor appointed as a representative of the upstream state, agreed that finding consensus on the conditions and constraints of the study was an accomplishment. Haggard said those preliminary boundaries will "guide as we go forward" with what has been a more than three-year process.

"I think the biggest sticking point right now is how the committee decides to interpret what frequency and duration of measure — what ... that mean in terms of the committee's charge," Haggard said. "I hope we can come to a consensus and have a final report that all committee members are happy with ... If it splinters, it will splinter down the state line and that is not a success in my view."

That type of disagreement is what led to the second statement of joint principles, the formation of this committee and undertaking of the stressor-response study. A technical advisory group spent more than a year reviewing the validity of Oklahoma's scenic rivers phosphorus standard of 0.037 mg/L, which was adopted in 2003.

A majority report generated by the advisory group validated the numeric standard, clearing the way for enforcement. A minority report backed by two Arkansas regulatory agencies disputed that finding, setting the stage for a lawsuit that was avoided by the agreement executed Feb. 20, 2013.

Oklahoma's numeric phosphorus standard was set in an effort to address degradation of water quality within the Illinois River watershed caused by a growing population and unregulated agricultural practices. Stream overloading of nutrients such as phosphorus and nitrogen promotes vegetative growth, which depletes dissolved oxygen levels, reduces water quality, threatens aquatic life and depreciates aesthetic beneficial uses.

Ed Brocksmith, a co-founder of Save the Illinois River Inc., told committee members Thursday that as they consider the weightier issues, he hopes they are mindful of the importance of the Oklahoma's scenic rivers system.

"STIR appreciates your hard work and the tough decisions you have to make," Brocksmith said on behalf of the Tahlequah-based clean-water coalition's members. "But … our members won't accept, and we pray you don't accept Oklahoma's scenic rivers being scenic only X percent of the time — they should be scenic all of the time."

The six-member panel will resume its recessed meeting Dec. 2. A location has yet to be determined.

Reach D.E. Smoot at (918) 684-2901 or dsmoot@muskogeephoenix.com.