SNTEMP (In)Frequently Asked Questions: Biological Issues

Q22. For protection of smolts, which variable do you believe (given the state of current knowledge) is the most defensible: flow and water temperature? Certainly defining target temperatures as I have done carries a lot of uncertainties as you pointed out in your comments. A lot of the uncertainties are affixed to uncertain migrational responses to varying year types that exhibit varying flow and temperature patterns. In this light, I am wondering if we would have a stronger position going towards natural spring flow patterns of respective hydrologic year types entirely and describing the benefits of flow and water temperature, rather than have water temperature targets drive the shapes of the hydrographs.

A22. I’m not sure I’m qualified to answer this one, but I’ll take a stand just for the heck of it. I could, if pressed, argue the other side of the coin, but that’s my curse.

Though it’s true that there are a lot of uncertainties in the biological data, it seems reasonable to me to try to define the limiting factors and see what can be done to alleviate them. This makes more sense to me than trying to hang one’s hat on the natural flow paradigm, though this might tell us if any proposal is really foolish, and gives a clue or clues to a more complete picture of the river’s shaping events. No matter what we do, there will be unexpected consequences, but that’s what learning is all about.

We likely have a pretty myopic picture of what "natural" really is. For example, measured temperature data for the River T. only goes back to 1959 with most of that being reservoir influenced. There is "evidence" that the region has been warming slowly through this period, natural or other otherwise, and evidence that the river is narrower and more vegetated now than it once was; this may have tended to cool it. How all that sorts out I haven’t a clue, but you probably do.

If I were a salmon, I’d have been up towards the headwaters, not so much below the current dam location I think. And that’s yet a different story because we are trying to force headwater temperatures and main stem flows together on spawning and incubating fish. What a collective squeeze!

Q48. In your opinion, is it appropriate to use SNTEMP data output to recommend flows necessary to meet a temperature criterion? If yes, what are the weaknesses in doing this (because this will end up in court)? If no, what is the "appropriate" use of SNTEMP output?

A48. Yes indeed. This is exactly what a model is for and we must defend the use of competent models in court. You guys have done a good job defining the targets, i.e., exactly when, where, how much, and for which species. [Added 12/2001]

Q104. Do you have any references for how states can put together meaningful water temperature metrics or thresholds for Atlantic salmon?

A104. The Forest Science Project at Humboldt State University did an elaborate investigation of a variety of water temperature metrics, including a statistical analysis of their spatial and temporal variation. This is part of a very large report available at http://www.humboldt.edu/~fsp/exec_sum_0500/index.shtml. The disadvantage of this report (other than length) is that they did little biological analysis.

Carl Armour has some relevant material. It may be found at http://www.fort.usgs.gov/products/publications/2185/2185.asp

One of the more interesting evaluations to have come along is one done by David Hines at The Timber Company. The best metric of ten evaluated to explain coho salmon presence/absence was the number of days exceeding a fixed maximum daily threshold (happened to be 17.6°C). Unfortunately, his draft paper has not been published due to some perceived inadequacies in his statistical treatment. However, if you look at his paper, the results are straightforward.

EPA Region 10 is involved in an extensive review of thermal standards. I'm note sure if this is all final, but check http://yosemite.epa.gov/R10/WATER.NSF/1507773cf7ca99a7882569ed007349b5/5eb9e547ee9e111f88256a03005bd665?OpenDocument. If that funny address doesn't work, start with http://yosemite.epa.gov/R10/WATER.NSF then select water quality standards, then temperature project technical issue papers, then paper 5. The material dealing with metrics is mixed in, but very well treated.

Dale McCullough produced an excellent document: A review and synthesis of effects of alterations to the water temperature regime on freshwater life stages of salmonids, with special reference to chinook salmon. By D.A. McCullough. U.S. Environmental Protection Agency, Seattle, Washington. EPA 910-R-99-010. 1999. 279 pp. (Also available on the Internet at http://www.critfc.org/tech/EPAreport.htm). One section in particular is relevant: TEMPERATURE INDICES SUGGESTED FROM THEIR APPLICATION IN THE LITERATURE on page 168.

See Chuck Coutant's report at https://www.osti.gov/servlets/purl/9042-gm4qBD/webviewable/
Note the HTTPS. Give it some time to download. If you have trouble with the web site, it is Coutant, C.C. 1999. Perspectives on temperature in the Pacific Northwest's fresh waters. Oak Ridge National Lab Environmental Sciences Division Publication No. 4849, ORNL/TM-1999/44

Kate Sullivan is doing some interesting work. See Sullivan, K., D.J. Martin, R.D. Cardwell, J.E. Toll, and S. Duke. 2000 (draft). An analysis of the effects of temperature on salmonids of the Pacific Northwest with implications for selecting temperature criteria. Sustainable Ecosystems Institute. http://www.sei.org/pub.html#reports.

My recommendation - keep it as simple as you can get away with. Though the world is complex, it is all too easy to over complicate metrics. [Added 6/2002]

Q105. Are there any IFIM or other publications that deal specifically with temperature tolerances of trout? How about any regulatory requirements?

A105. The closest I know is Armour's pub, which may be found at http://www.fort.usgs.gov/products/publications/2185/2185.asp. Most of what I know deals with salmon, but you should be able to find similar material in the literature. [Added 6/2002]

Q175. I will need to be running SNTEMP to generate macrohabitat-flow relationships, and then doing numerical integration. Am I way off track? Is there an easier approach I've overlooked?

A175. No, you are not off track. We wrote some software some years ago that did this automatically, but we are not really supporting that anymore and it is easy to do in a spreadsheet these days.