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Ii il II . " " . 'I :1 'I . Western States Water Council Water Quality Committee Sheridan, Wyoming October 5, 2006 Joan Card mentioned she believed she had glanced through a 350 page manual put out by EP A on hydro modification. She wasn't sure if there were any clues in that or not. Even in EP A's perspective, you only have to list if there is a pollutant, not pollution. Obviously, you can get into complex situations where it's difficult to sort out what is causing what, and whether it's purely a hydrologic modification without some associated chemical problem. Another issue in Colorado is temperature standards. We have temperature standards that have been on the books since the late 1970s. Basically, they don't make a whole lot of sense, and no one has figured out what they were suppose to mean and they have never been used before. Everyone recognizes that we need to update our temperature standards. We've been trying to do that over the last few years and there's been a fair amount of progress in terms of identifying new values for both cold and warm water streams. It's been a lot of work developing databases based on available research with different species and putting species into different categories based on our cold/warm water streams and considering complications in the transition areas where we have differences depending on whether particular species are there or not. There's a more significant challenge with respect to the issue ofthermal shock or the change in temperature. Leaving the absolute numbers aside, if the discharge increases the temperature by more than a certain amount, when does that have an adverse affect? One ofthe options on the table is a 3 degree change from upstream to downstream as a limit and we've got a fair number of votes. Trout Unlimited, who is mostly concerned about the cold water areas of the state is coming in and arguing that there is good science to show there are adverse impacts. In fact, they believe they are being very reasonable with the 3 degree number and they think that number could be 1 or 2 degrees and be more appropriately protected. Also in Colorado, one of the biggest challenges we face is the practicalities of what we come up with and how we implement the municipal wastewater treatment discharges. Clearly, municipal wastewater treatment discharges, particularly in certain months ofthe year, are significantly warmer than the stream. So you have a differential for many of the municipal discharges that are greater than 3 degrees. The biologists and wildlife folks say, "Well that can have an adverse impact in part because you have more of a constant temperature and don't have the fluctuations which could be important for the reproductive cycle. At least you have that possibility." We don't have major temperature problems. At least we've never identified that as a big concern. We're trying to figure out how these pieces fit together and go forward. Has any other state looked at a need to impose some kind of controls on the municipal dischargers because of the constant temperature of their effluent and if so, what have you done? In Washington, we have a cold/warm water species standards. Weare on temperature limits for streams and in some cases rivers. We are either getting the discharge out of the stream or in one case, we are trying to look at some kind oftrading scenario similar to what Oregon is doing - seeing if we can plant enough agricultural work upstream'. We haven't figured out whether it will work in this particular case or not because we haven't done the modeling yet. 9,