Rip Stream Quantifying stream temperature response to Oregon

Rip. Stream: Quantifying stream temperature response to Oregon timber harvest practices Jeremy Groom 1, Liz Dent 2, Lisa Madsen 3 1 OSU Dept. of Forest Engineering Resources & Management 2 Oregon Dept. of Forestry, 3 OSU Dept. of Statistics

In a time before streams…

Oregon Department of Forestry Monitoring Private Forests Division Landslides Pesticides Leave-tree HAP Shade Stream Temperatures

Clean Water Act & OR Forestry Clean Water Act DEQ (Water Quality Rules) EPA Forest Practices Act Board of Forestry Monitoring

Rip. Stream – Riparian Function and Stream Temperature State and Private Forests joint effort • Objective: Evaluate effectiveness of forest practices rules & strategies at protecting stream temperature, promoting riparian structure • 33 Sites (18 Private, 15 State, Medium and Small F) • Dent et al. 2008 JAWRA 44(4): 803813

Rules and Strategies Private Forests Limited Entry No Cut 70 ft 50 ft 20 ft Small F Medium F State Forests No Cut Limited Entry 25 ft Small & Medium F Private: Forest Practices Act State: Northwest Oregon State Forest Management Plan 170 ft

Rip. Stream Study Design: 2 years pre-harvest, 5 years post harvest 1 W Treatment Control 2 W POINT OF MAXIMUM IMPACT 3 W Downstream 4 W

Rip. Stream – Data and Questions Years of data collection - Stream temperature - Shade - Channel morphology (gradient, widths, etc. ) - Riparian vegetation (trees, shrubs) What questions do we address first? – Regulatory: do our streams meet DEQ temperature standards post-harvest? – Function: what site characteristics are related to temperature change post-harvest?

DEQ Water Temperature Standard Biologically-Based Numeric Criteria – were stream temperatures raised above 16 C or 18 C? • Not really • Analysis: Relatively straightforward Protecting Cold Water (PCW) – were streams warmed by > 0. 3 C? • Yes, on private (not State) streams • Analysis: Complex

7 Day. Max “Temperature” = 7 -day moving average of maximum daily temperatures Day: 1 2 3 4 5 6 7 8 9 10 11 Temp: 11 12 10 11 9 8 9 9 10 10 9 7 Day. Max: 10. 0 9. 7 9. 4

Numeric Criteria Is analysis guidance available? YES Numeric Criteria exceedance = Any single summer 7 Day. Max temperature value exceeds 16 C or 18 C Natural: Control probes 1 W & 2 W Potential harvest effect: Treatment probe 3 W

Numeric Criteria – What’s the big deal? • Widespread WQ rule type • EPA guidance (2003) for PNW states • Lots of effort & research • Opportunity for evaluation

Numeric Criteria Results: 16 C • Total Number of Sites: 33 – 18 sites exceeded 16 C • Of those 18 sites: – 3 sites = pre-harvest only – 10 sites = control (1 W, 2 W) and treatment (3 W) probes during the same year or years – 3 sites = control probes during pre-harvest years; treatment probes during post-harvest year(s) – 2 sites = treatment probe post-harvest only No strong indication that standards exceeded

Protecting Cold Water (>0. 3 C) • Is analysis guidance available? NO. Lacking in other states Collaboration with DEQ Analysis question: For a specific day, has stream temperature increased by > 0. 3 C?

PCW analysis Looking for change in relationship (e. g. , Treatment Reach = 2 W and 3 W) Comparing pairs of years (e. g. , 2002 & 2004) within a reach (e. g. , Upstream Control) Years are either pre-harvest or post-harvest (can compare pre-pre, pre-post, post-post)

PCW – Analysis Path 1) Which reach year-pair comparison “exceeded” PCW? 2) Created & compared explanatory models of exceedance patterns – Examined combinations of regulatory distinctions (medium & small streams, State and Private lands) – Also examined comparison timings (e. g. , preharvest to post-harvest)

Study Design and the PCW • 3 reaches X 3 time periods = 9 groups 1 W 3 W 2 W FLOW 4 W Upstream Control 614 comparisons total Treatment 65 exceedances Downstream Pre-pre Pre-post Post-post

Models Main Models 1) Null (all categories equal) Pre-pre Pre-post Post-post Upstream Control 2) Reaches differ Treatment 3) Timing differs Downstream 4) Everything differs 5) Pre-post treatment differs 6) Pre-post Private treatment differs Best State Forest Model ?

Best models 40. 2% TOP MODEL 4. 6%

Conclusions (Regulatory) • Numeric Criteria – OK(? ) • PCW – increase in exceedance frequency on Private streams in general • PCW – State OK

Functional Analysis Study scope: Preharvest and two years postharvest 33 sites Questions: What factors influence changes in Treatment Reach temperature? Magnitude of temperature change?

What are we quantifying? • Changes in temperature (downstream – upstream) • Averaged daily values (July 15 – Aug 23) – Maximum – Minimum – Average – Flux 1 W 2 W 3 W FLOW 2 W-1 W = Change in Control Reach 3 W-2 W = Change in Treatment Reach

What factors control Treatment Reach temperature change? Gradient Elevation Reach length 1 W 2 W 3 W FLOW Control reach temperature change Azimuth Watershed area Shade

Approach 1) Determine appropriate statistical analysis Linear mixed-effects regression 2) Develop competing explanations (models) of how temperature change controlled 18 models, ranked AIC 3) Determine which explanation performed best 4) Examine model results

Maximum Temperatures Best model: Change in maximum temperatures explained by: -Temperature change in control reach -Treatment reach length -Gradient -Shade Random: ~ Intercept + Control Temperature|Site Model values statistically significant Models without shade performed poorly

Other Temperature Metrics Minimum Temperature: Same top model, same behavior of variables (not as strong) Average Temperatures: ditto Flux: Increased daily fluctuations with less shade Implication: Reductions in shade occurred, linked to increase in daily temperature maximum, minimum, average, and flux

Shade Pre & Post Harvest

Partial Residual Plot for 33 Sites

Results summary 1) Shade changed and related to temperature change 2) Other parameters seem reasonable 3) Shade is important & needs further exploration -BA, height, blowdown

Next steps • Complete & publish current analysis • Next analysis: 5 yrs post harvest – Did temperature patterns remain? – Did shade recover? – More detailed examination of vegetation and shade

Acknowledgements v v v Liz Dent (ODF) & Joshua Seeds (DEQ) Private landowners PF monitoring staff (Marganne Allen, Jerry Clinton, Kevin Nelson, Kyle Abraham, Seasonal Work Force, Stewardship Foresters) State Forests Program Staff (Jeff Brandt, District Foresters, Field Foresters) Review Committee Members EPA 319 program