Quantifying the Benefits of Stream Restoration Efforts in the Lake Tahoe Basin: FINAL REPORT APPENDIX B. TROUT CREEK WY10 DATA COLLECTION SUMMARY 2NDNATURE, LLC | ecosystem science + design www. 2ndnaturellc.com | 831.426.9119 Quantification and Characterization of Trout Creek Restoration Effectiveness; Focused Development of a Stream Load Reduction Tool (SLRT) Methodology WY2010 Data Collection Summary p.1 WY2010 DATA COLLECTION SUMMARY 2NDNATURE developed a detailed characterization plan in preparation for this research, including Stream Load Reduction Tool (SLRT) methodology, instrumentation selection and field data collection protocols. Please see the Final Characterization Plan (available for download at: ftp://2ndnaturellc.com/2ndnature/2NDNATURE_Reports/Lake%20Tahoe/SLRT_Trout%20ChPlan_Final%20April%2
02010.pdf ) for complete details. This document serves as an interim status report to update the Technical Advisory Committee (TAC) on the WY2010 data collection efforts and document the planned WY2011 data collection strategy by the research team. Some preliminary analyses of the data are provided to inform adjustments to data collection efforts for WY2011. All analyses are preliminary and will continue to be completed and refined as the research continues. RESEARCH GOALS AND OBJECTIVES Quantification and Characterization of Trout Creek Restoration Effectiveness; Focused Development of a Stream Load Reduction Methodology (SLRT) has been funded by USFS SNPLMA Round 9 grant funds with a contract awarded to the 2NDNATURE team in August 2009 with expected completion on 02/06/2012. The research team, in collaboration with the TAC members, agreed upon the following research goals and objectives in March 2010. GOALS 1.
2.
Provide detailed guidance on the recommended methods to quantify the water quality benefit of stream restoration in the Lake Tahoe Basin. Characterize the “desired condition” analog of a restored stream morphology and condition in the Lake Tahoe Basin (Trout Creek) by directly applying techniques developed by 2NDNATURE and others for Lake Tahoe streams. OBJECTIVES a.
b.
c.
d.
Create and assess a range (based on complexity) of methods to quantify the total and fine sediment load reduction of stream restoration efforts in the Lake Tahoe Basin, using Trout Creek as the case study. Compile and apply available data to inform the inputs and validate the outputs of Stream Load Reduction Tool (SLRT) estimates. Design and implement a detailed data collection effort from Trout Creek (WY2010 and WY2011) to augment existing data and directly inform SLRT assumptions, input parameters and validate results. If resources are available in WY2011, apply the riverine module of California Rapid Assessment Methodology (CRAM) to Trout Creek and other sites as appropriate to test applicability of CRAM to discern pre and post restoration effects and detect differences in SEZ condition in the Lake Tahoe Basin. SITE INSTRUMENTATION Instrumentation installed and/or utilized by the 2NDNATURE team within the Trout Creek Restoration project area (Figure 1) are summarized in Table 1 below. Locations of 3 water level recorders at 2NDNATURE sites and 3 turbidity sensors at USGS stream gage locations are displayed in Figure 2. The following provides general concepts of the data collection techniques and an initial summary of the analysis to date. Martin Ave
Trout Creek
(Post-Project)
SANTA CRUZ COUNTY
Trout Creek
(Pre-Project)
san Francisco
Cold Creek
santa Cruz
CaLIFoRnIa
City of
santa Cruz
Los angeles
Lake Tahoe
CaLIFoRnIa
nEvaDa
Pioneer Trail
Figure1:X.X:
Trout Creek
floodplain
transect
pin locations
FIGURE
Differences
between
LTIMP
and TMDL
watershed bound(Total
= 111
Pins
over
8 transects).
aries.
FIGURE
Data
1:
Trout
plotted
Creek
over
geography.
Lake
Tahoe Basin digital elevation model,
along with county boundaries.
Feet
0
200
400
800
LEGEND
LEGEND
TCMA 10336780
Instrument Locations
SOURCE
2NDNATURE
USGS
REACH5
REACH3
CCPT 10336778
REACH1
TCPT 10336775
Figure X.X: Approximated Water Surface Extents (WSE) for peak
flow conditions
during
WY2009.locations by source.
FIGURE
2: Trout Creek
instrument
Feet
0
250
500
1,000
Quantification and Characterization of Trout Creek Restoration Effectiveness; Focused Development of a Stream Load Reduction Tool (SLRT) Methodology WY2010 Data Collection Summary Table 1: Trout Creek instrumentation summary for WY2010 (see Figure 2 for locations) Instrument BaroTroll Level Troll YSI USGS Gage Location EI Office START STOP 10/18/07 14:00 06/29/10 10:15 Reach 1 09/30/09 00:01 07/08/10 18:15 Reach 3 09/18/09 11:00 07/01/10 11:15 Reach 5 09/18/09 11:00 07/08/10 09:15 TCPT 04/13/10 03:00 07/08/10 08:45 CCPT 04/12/10 22:00 07/08/10 09:15 TCMA 04/12/10 20:00 07/08/10 09:30 TCPT‐10336775 03/01/90 00:00 09/06/10 11:15 CCPT‐10336778 03/31/10 17:45 08/05/10 17:00 TCMA‐10336780 06/22/00 07:15 09/06/10 11:00 p.4 Purpose Used to correct LevelTroll data. 15 min water surface elevations at 3 locations within restored reach. 15 min turbidity and stage recorders installed at existing or previous USGS flow stations. USGS flow data used as input to Trout Creek restored reach Flow data at site extrapolated using relationship with archive data between CCPT and TCPT. USGS flow data used as output from Trout Creek restored reach WATER LEVEL RECORDERS Three In‐Situ Level Troll 500 instruments collected continuous (15‐minute interval) stage data at each reach location (Figure 2, 2NDNATURE locations) to monitor site hydrology. Staff plates were installed concurrently and each sampled 4‐6 times during the deployment to provide QA/QC. An In‐Situ BaroTroll instrument was placed at Environmental Incentives main office nearby in South Lake Tahoe to correct for natural variation in atmospheric pressure of the Level Troll level readings. All instrument elevations were tied into existing cross section benchmarks as established by Swanson Hydrology in 2000 to provide continuous absolute water surface elevation at each 2NDNATURE stage recorder. TURBIDITY TO FSP LOADING Three YSI 600OMS water quality monitoring instruments collected continuous (15‐minute interval) turbidity and depth at each USGS stream gage location within the extents of the project area (Figure 2, USGS locations). Surface water grab samples were collected 13 times during summer 2010 at each location under incremental increases in spring discharge, approximately every 10 cfs increase over the spring snow melt duration with the first sample taken at 40 cfs. All water samples were analyzed in the field for turbidity using a Hach 2100P portable turbidimeter to QA/QC instrument turbidity time series presented in Figure 3. Samples were analyzed by WETLab for TSS and % of TSS < 16um by mass, allowing a calculation of FSP concentrations in mg/L. FSP concentrations were correlated with instrument turbidity at the time of collection to provide a turbidity to FSP rating curve (Figure 4) that was used to generate a continuous time series of FSP concentrations for each of the 3 YSI locations (Figure 5). Surface water discharge data was simultaneously recorded by USGS gaging stations at TCPT and TCMA (Figure 2, USGS locations). A previous USGS gage was temporarily operated at CCPT from 2001‐2003. A linear regression was created using simultaneous discharge measurements from archive data at CCPT and TCPT gage sites (2001‐2003; Figure 6) to calculate CCPT discharge data for WY2010 (Figure 5). USGS discharge data and FSP concentration time series at each location (Figure 5) were multiplied to create an FSP discharge time series (Figure 7). This FSP discharge time series (kg/s) was integrated over different time periods to quantify net 70
8
Trout Creek at Pioneer Trail
TCPT
Turbidity
Grab Samples
Water Depth
60
7
Staff Plate Reading
6
50
4
30
Water Depth (ft)
5
40
3
20
2
10
1
0
0
4/12/10
70
4/26/10
5/10/10
5/24/10
6/7/10
6/21/10
Cold Creek at Pioneer Trail
CCPT
7/5/10
Grab Samples
7
60
Turbidity (ntu)
5
40
4
30
Water Depth (ft)
6
50
3
20
2
10
1
0
0
4/12/10
70
4/26/10
5/10/10
5/24/10
6/7/10
6/21/10
Trout Creek at Martin Avenue
TCMA
7/5/10
8
Turbidity
Grab Samples
Water Depth
60
7
Staff Plate Reading
6
50
40
4
30
Water Depth (ft)
5
Turbidity (ntu)
Instrument Turbidity (NTU)
8
Turbidity
3
20
2
10
1
0
4/12/10
0
4/26/10
5/10/10
5/24/10
6/7/10
6/21/10
7/5/10
Instrument Turbidity & Depth Time Series
FIGURE 3
Instrument Turbidity to Measured FSP Concentration by Site
30
y = 0.60x
R² = 0.96
Meassured FSP Concentration (mg/L)
25
20
TCPT
15
CCPT
TCMA
5
Li
Linear (5)
(5)
10
5
0
0
5
10
15
20
25
30
Instrument Turbidity (NTU)
instrument Turbidity to measured fsp relationship
FIGURE 4
180
60
Trout Creek at Pioneer Trail
FSP Concentration
TCPT
USGS Discharge
160
50
140
FSP C
Concentration (mg/L)
100
30
80
20
Discharge (cfs)
120
40
60
40
10
20
0
0
4/12/10
60
4/26/10
5/10/10
5/24/10
6/7/10
Cold Creek at Pioneer Trail
CCPT
6/21/10
7/5/10
180
FSP Concentration
Calculated Discharge
160
120
40
100
30
80
20
Discharge (cfs)
140
Discharge (cfs)
FSPFSP C
Concentration
(mg/L)
Concentration (mg/L)
50
60
40
10
20
0
0
4/12/10
60
4/26/10
5/10/10
5/24/10
6/7/10
6/21/10
Trout Creek at Martin Avenue
TCMA
7/5/10
180
FSP Concentration
USGS Discharge
160
50
140
FSP C
Concentration (mg/L)
100
30
80
20
Discharge (cfs)
120
40
60
40
10
20
0
0
4/12/10
4/26/10
5/10/10
5/24/10
6/7/10
6/21/10
7/5/10
FSP Concentration & Discharge time series
FIGURE 5
TCPT - CCPT Discharge Rating Curve
50
y = 0.3165x + 3.0844
R² = 0.8364
45
40
20001‐2003 CCPT Discharge (cfs)
35
30
25
20
15
10
5
0
0
20
40
60
80
100
120
140
2001‐2003 TCPT Discharge (cfs)
TCPT - CCPT Discharge relationship
FIGURE 6
0.09
Trout Creek at Pioneer Trail
TCPT
0.08
0.07
FSP Discharge (kg/s)
0.06
0.05
0.04
0.03
0.02
0.01
0
4/13/10
0.08
5/3/10
5/23/10
6/12/10
7/2/10
5/23/10
6/12/10
7/2/10
5/23/10
6/12/10
7/2/10
Cold Creek at Pioneer Trail
CCPT
0 07
0.07
FSP Discharge (kgg/s)
0.05
0.04
0.03
0.02
0.01
0
4/13/10
5/3/10
0.08
Trout Creek at Martin Avenue
TCMA
0 07
0.07
0.06
0.05
FSP Discharge (kgg/s)
FSP Discharge (kg/s)
0.06
0.04
0.03
0.02
0.01
0
4/13/10
5/3/10
FSP Discharge time series
FIGURE 7
Quantification and Characterization of Trout Creek Restoration Effectiveness; Focused Development of a Stream Load Reduction Tool (SLRT) Methodology WY2010 Data Collection Summary p.10 FSP loads for event durations of interest and the results are presented in the June 2010 Overbank Event Summary below. FLOODPLAIN TRANSECTS To expand the floodplain characterization at Trout Creek to cost‐effectively and systematically evaluate evidence of sediment retention as a result of floodplain inundation, 2NDNATURE installed 8 floodplain‐wide transects using 3 foot rebar stakes in March 2010, before spring snowmelt (Figure 8). After peak flows receded, floodplain transects were resurveyed by field personnel to measure changes in surface elevation at the pin (i.e. sediment deposition), vegetation characteristics, peak flow and/or sediment indicators and water retention depth at discrete locations along the restored reach. Figure 9 illustrates the area of inundation throughout the project area at the spring snow melt peak (TCPT, 127 cfs at 6/8/10 0:45; TCMA, 168 cfs at 6/8/10 14:15) as estimated using floodplain topography and 2NDNATURE stage recorder data. Also displayed in Figure 9 is the relative height of visual peak flow indicators in inches above the ground as observed during floodplain transect surveys. Figure 10 presents the relative maximum height in inches of observed sediment film on vegetation above the ground at each observation point. Analysis plots were created (Figure 11) of peak flow and sediment indicator height correlations with relative change in height at the pin. Both maximum flow indicator height (A, Figure 11) and sediment indicator height (B, Figure 11) indicate a positive signal of sediment deposition on the floodplain amidst the variability and background noise. Dominant vegetation categories (C, Figure 11) are sorted by number of occurrence where observations of sediment film on vegetation also provide a positive indication of floodplain sediment retention. CROSS SECTION SURVEYS Utilizing previous and continued cross section data from Trout Creek, 14 cross sections were resurveyed by 2NDNATURE in summer 2010 to quantify potential channel aggradation/degradation as a result of the 2010 flow event that will be used to make sediment volume estimates. Cross sections that were surveyed by 2NDNATURE were evenly spaced throughout the project reach and distributed based on relative stability of the channel within the cross section. Of the 14 cross‐sections, 6 original rebar benchmarks were relocated; other benchmark locations were approximated using coordinates from NSL 2008 survey and GPS in the field. Table 2 summarizes 2NDNATURE’s cross section resurvey efforts for 2010 and Figure 12 provides one example of the available cross section time series. Additionally, the CTC subsequently completed a resurvey of all the Trout Creek cross sections (except for 2 that did not have recovered benchmarks) in fall 2010 (S. Carroll, pers. comm.). These data will be incorporated into 2NDNATUREs analysis of channel sediment generation once the final data are provided by the CTC. In addition to cross sectional surveys, existing data provided by CTC contains a thalweg longitudinal survey that was surveyed in 2001, 2002, 2003 and 2008. LEGEND
LEGEND
Floodplain Transect Pins
1
2
34
5
6
7
8
Figure X.X: Trout Creek floodplain transect pin locations
(Total 8:
= 111
Pins floodplain
over 8 transects).
FIGURE
Installed
transects with pin locations.
Feet
0
225
450
900
LEGEND
LEGEND
Peak WSE
Floodplain Transect Pins
Max Flow Indicator Ht (in)
0.0 - 1.0
1.1 - 4.8
4.9 - 12.0
12.1 - 21.5
1
2
34
5
6
7
8
FIGURE 9: Measured floodplain transects with maximum flow inFigure X.X: Approximated Water Surface Extents (WSE) for peak
dicator height, in inches, displayed over approximated peak waflow conditions during WY2009.
ter surface extents for instrumentation period during WY2010.
(Peak flow = 06/08/10)
Feet
0
250
500
1,000
LEGEND
LEGEND
Floodplain Transect Pins
Max Sediment Indicator Ht (in)
0.0 - 1.0
1.1 - 5.0
5.1 - 12.0
12.1 - 21.5
1
2
34
5
6
7
8
Figure X.X: Approximated Water Surface Extents (WSE) for peak
FIGURE 10: Measured floodplain transects with maximum sediment
flow conditions during WY2009.
indicator height, in inches, displayed at pin locations.
Feet
0
250
500
1,000
Change in height by peak flow indicator height
3.00
2.00
A
Change in heiight (in)
1.00
0.00
‐1.00
‐2.00
‐3.00
3 00
0.0
5.0
10.0
15.0
20.0
25.0
Maximum flow indicator (in)
Change in height by sediment indicator height
3.00
2.00
B
Change in height (in)
1.00
0.00
‐1.00
‐2.00
‐3.00
0.0
5.0
10.0
15.0
20.0
25.0
Maximum sediment indicator (in)
Change in height by vegetation class
1
0.8
0.6
C
Change in height (in)
0.4
0.2
0
‐0.2
‐0.4
‐0.6
‐0.8
‐1
Floodplain transect analysis plots
FIGURE 11
260.5
260
259.5
Elevation ((ft)
259
258.5
2001
2002
2003
258
2008
2010
257.5
257
256.5
256
0
5
10
15
20
25
30
Distance (ft)
321 Frederick Street, Santa Cruz, CA 95062
www.2ndnaturellc.com
TEL: 831.426.9119 FAX: 831.421.9023
Figure 12: Cross section time series for XS 3D. Years 2001 - 2003 were collected by Swanson, 2008 by NSL
and 2010 by 2NDNATURE.
35
Quantification and Characterization of Trout Creek Restoration Effectiveness; Focused Development of a Stream Load Reduction Tool (SLRT) Methodology WY2010 Data Collection Summary Table 2: Trout Creek cross section survey 2NDNATURE summer 2010 Reach XS ID Reach Type Relative Stability of Channel Benchmark Found 1 1A Straight Stable No 1 1B Bend Dynamic No 2 2A Straight Stable No 2 2B Bend Dynamic No 3 3A Bend Stable No 3 3D Straight Stable Left Rebar 4 CTC1 Bend Dynamic No 4 4A Straight Stable No 4 4D Bend Dynamic No 5 CTC6 Bend Dynamic Left Rebar 5 5B Bend Dynamic Left Rebar 5 5D Bend Dynamic Left Rebar 6 6A Straight Dynamic Left Rebar 6 6D Straight Dynamic Left Rebar p.16 JUNE 2010 OVERBANK EVENT SUMMARY With a slightly above average snowpack accumulated over 2009‐2010 winter and a rapid spring snow melt period, Trout Creek exceeded channel capacity and was able to access a large portion of the existing floodplain upstream of the Cold Creek confluence. This is further referred to as the overbank event, in which the channel capacity of Trout Creek, described below, was exceeded for an extended period of time (i.e. continuous days overbank). Analysis of the water level data indicate that the peak flow occurred on June 8, 2010 in the afternoon with a maximum discharge of 168 cfs recorded at TCMA. In combination with the cross section data, visual floodplain surveys and water level recorders were used to capture maximum water surface elevation during the June 2010 flood. Water surface extents of this event were approximated in ArcGIS using collected and available elevation data and mapped over a recent aerial image (Figure 9). Some preliminary calculations were conducted using existing data to assess WY2010 data collection and establish additional requirements for WY2011. Analyses will be improved and revised following data collection in WY2011. Channel capacity at each 2NDNATURE stage recorder was calculated using cross section geometry from 2010 survey data and Manning’s equation (Table 3). This analysis suggests the average channel capacity of Reach 1, 3 and 5 (Figure 2, 2NDNATURE locations) is approximately 60 cfs, 110 cfs and 190 cfs respectively. This increase in channel capacity is illustrated by the extensive floodplain inundation upstream of the confluence and minimal inundation downstream (Figure 9). Field observations and discharge data from TCMA suggest that inundation of the east floodplain below Cold Creek was not overbank flow from the Trout Creek channel, but rather elevated groundwater and isolated saturated meadow conditions on topographically lower surfaces and diverted flow due to backwatering of Cold Creek associated with beaver dam construction. Thus, it is assumed that during the June 2010 overbank event FSP retention on the floodplain as a direct result of overbank flow was limited to the area upstream of Cold Creek confluence. Quantification and Characterization of Trout Creek Restoration Effectiveness; Focused Development of a Stream Load Reduction Tool (SLRT) Methodology WY2010 Data Collection Summary p.17 Table 3: Preliminary channel capacity calculations for Trout Creek instrument sites using available data sources Average Wetted Channel XS Area1 Vbkf4 Channel 1
1
2 3
4
SITE XS ID Perimeter Slope
n Capacity (ft²) (ft/s) Capacity4 (ft) (ft³/s) (ft³/s) 1A 30.6 17.4 0.0018 0.04 2.29 70 2A 21.0 16.7 0.0018 0.04 1.83 38 Reach 1 60 2B 35.1 21.8 0.0018 0.04 2.16 76 3A 49.6 22.0 0.0018 0.04 2.69 134 3D 39.9 20.9 0.0018 0.04 2.41 96 Reach 3 110 4A 38.2 19.2 0.0018 0.04 2.48 95 5B 61.2 26.3 0.0018 0.04 2.75 168 5D 69.2 26.8 0.0018 0.04 2.95 204 Reach 5 190 6A 60.3 20.5 0.0018 0.04 3.21 194 6D 67.4 26.5 0.0018 0.04 2.92 197 Integration of USGS discharge time series with respect to channel capacity at each instrument site yields the total volume of water that exceeded channel capacity and presented in Figure 13. Using calculated channel capacity at each stage recorder location (Table 3) and TCPT discharge time series for Reaches 1 and 3 and TCMA discharge time series for Reach 5, total volume that exceeded channel capacity during the WY2010 snow melt event was calculated. Results indicate that overbank volume of surface water decreases downstream, where no overbank flow occurred near the Reach 5 site, 11 acre‐feet of overbank occurred near the Reach 3 site and 703 acre‐feet of overbank occurred near Reach 1. These numbers will continue to be refined with subsequent calculations once CTC cross section data become available to recalculate channel capacity by reach. FSP loading at each YSI/USGS site was calculated to determine if a net FSP reduction as a result of floodplain retention could be measured using the collected water quality dataset. The ability to measure a net reduction also assumes that FSP retention on the floodplain exceeded the amount of FSP generated from in channel erosion and that these differences are significant enough for the existing instrumentation to measure a difference. All surface water and FSP discharge were aligned by date using Access 2007 and categorized whether or not discharge at TCPT exceeded channel capacity (60 cfs) of the restored upper portion of the Trout Reach as determined from 2010 cross sections. Overbank event duration as determined from the TCPT gage occurred from 6/3/2010 11:00 to 6/21/2010 15:00. For this time interval, FSP discharge was translated into FSP load by integrating each time series value by the interval (15‐minute) over the 11.9 day event at each YSI site. Similar calculations were made for pre‐
event to estimate error of FSP load measurements based on the assumption that pre‐ event channel erosion is insignificant before overbank conditions (ΔStorage 0) and for post‐event to give an indication of sediment generation produced from channel erosion after the overbank event (ΔStorage < 0). Data Sources: 1
2010 Cross Section (2NDNATURE) 2
2008 Longitudinal Profile (National Sediment Laboratory) 3
Estimation using Manning’s n Reference Table 4
Calculations 200
Trout Creek Reach 1
180
Overbank Volume
In Channel Volume
160
140
Discharge (cfs)
120
100
80
703 Acre-ft
Channel Capacity = 60 cfs*
60
40
20
6/28/10
6/17/10
6/7/10
5/27/10
5/17/10
5/7/10
4/26/10
4/16/10
4/5/10
3/26/10
200
TCPT Discharge
3/16/10
0
Trout Creek Reach 3
180
Overbank Volume
In Channel Volume
160
Discharge (cfs)
120
11 Acre-ft
Channel Capacity = 110 cfs*
100
80
60
40
20
Trout Creek Reach 3
Trout Creek Reach 5
180
180
0 Acre-ft
6/28/10
6/17/10
6/7/10
5/27/10
5/17/10
5/7/10
4/26/10
4/16/10
4/5/10
3/26/10
200
200
TCPT Discharge
3/16/10
0
Channel Capacity = 190 cfs*
Overbank Volume
Overbank Volume
In Channel Volume
In Channel Volume
160
160
140
140
120
120
100
100
80
80
60
60
* Channel capacity calculations
are preliminary estimates given
best available data and will
be refined with further data
acquisition in WY2011.
40
40
20
20
6/28/10
6/17/10
6/7/10
5/27/10
5/17/10
5/7/10
4/26/10
4/16/10
4/5/10
TCMA Discharge
3/26/10
00
3/16/10
Discharge (cfs)
Discharge (cfs)
Discharge (cfs)
140
instrument site discharge volumes
FIGURE 13
Quantification and Characterization of Trout Creek Restoration Effectiveness; Focused Development of a Stream Load Reduction Tool (SLRT) Methodology WY2010 Data Collection Summary p.19 Table 4 summarizes the event based calculation of FSP load (tonnes) by site for 3 discrete time series. The sum of TCPT and CCPT loads are assumed to be FSP load introduced to the Trout Creek project area (FSPin) and this approach assumes the entire FSP load measured at CCPT reaches Trout Creek. Additional inputs of FSP loads would include channel erosion within the restored channel itself, which was not included in this simple comparison, but will be considered during complete analysis next year. TCMA is located at the downstream boundary of the reach and the FSP load out of the system (FSPout), where: FSPin – FSPout = ΔStorage (change in storage). We would expect the pre‐event ΔStorage value to be zero prior to an overbank. Table 3 indicates the pre‐event ΔStorage is ‐0.6 tonnes, where the greater amount of sediment observed downstream can be partly accounted for by potential FSP generation within the channel at elevated flows below 60 cfs. Since no estimates of potential FSP generation was calculated from the available data during this exercise, the pre‐event data suggests that this method has a measurement error of ± 0.6 tonnes of FSP. Data presented in Table 3 imply a net retention of FSP on the floodplain during the overbank event; however, those gains in sediment reduction appear to be lost due to sediment production within the channel after the overbank event, which seems likely given that receding flows within areas where the channel capacity is > 100 cfs and banks are over steepened can trigger bank sloughing and failure. Evidence of fresh bank failure downstream of the Cold Creek confluence was noted by field personnel during post overbank field surveys. The results in Table 4 are promising and the addition of channel FSP generation estimates will further refine floodplain FSP retention estimates from this dataset. Table 4: FSP load calculations by site and mass balance calculations (tonnes) SITE Source TCPT FSP load 7.4 IN CCPT OUT TCMA PRE EVENT5 3.7 11.7 ΔStorage: NET 11.1 11.7 ‐0.6 OVERBANK EVENT6 FSP load 12.2 5.6 16.1 ΔStorage: NET 17.8 16.1 1.7 POST EVENT7 FSP load 1.6 1.5 5.5 ΔStorage: NET 3.1 5.5 ‐2.4 NEXT STEPS/LESSONS LEARNED One of the key objectives of the research project was to collect and apply available data to inform the inputs and validate the outputs of Stream Load Reduction Tool (SLRT) estimates. Substantial amount of relevant data has been collected to document the overbank event in WY2010, so the focus for WY2011 is to refine data precision through increased and more accurate recordings. Our ability to measure FSP load reductions from the WY2010 data is limited by the uncertainty with CCPT FSP loads and the fraction that actually reaches Trout Creek. In addition, the Trout Creek Reach downstream of the confluence evaluated has a channel capacity nearly double that of upstream reach and during a 120 cfs event minimal out of bank flow occurred within the lower section. These variations in channel capacity limit our ability to constrain FSP load retention on the floodplain in the upstream portions of the reach. Resources in WY2011 will be focused on obtaining reliable, continuous FSP discharge data from TCPT to just upstream of the Cold Creek confluence by the placement of a turbidity probe at the Reach 3 stage recorder. If an additional unit can be Event Duration: 5
Pre Event = 24.7 days 6
Overbank Event = 11.9 days 7
Post Event = 11.1 days Quantification and Characterization of Trout Creek Restoration Effectiveness; Focused Development of a Stream Load Reduction Tool (SLRT) Methodology WY2010 Data Collection Summary p.20 obtained, 4 turbidity units will be deployed for the 2011 snow melt, otherwise the CCPT turbidity instrument will be relocated to Reach 3. All other spring snow melt data collection will be completed as planned per the Characterization Plan developed in 2010. Our ability to obtain useful data will be subject to the occurrence of an overbank event during WY2011. FSP load reduction calculations hinge upon accurate FSP measurements and channel geometry characteristics. Additional cross sections will be implemented at each instrumentation site to better determine more accurate channel capacity and depth. The USGS discharge time series was used to quantify FSP loading into and out of the study area, where distinguishing between in channel flow and over bank conditions is critical information. Currently, the channel capacity at each USGS location is estimated from nearby cross sections and can be further refined using additional and more specific field data. MODEL DEVELOPMENT AND VERIFICATION Data analysis will continue through WY2011 to identify additional data collection requirements for model development and verification. Following data collection in WY2011, model development to estimate water quality benefit of Trout Creek restoration project will proceed and ultimately culminate with a technical report due in February 2012. Table 5: Project schedule and deliverable due dates. Task 1. Trout Creek Characterization Plan Obtain any applicable Trout Creek physical, chemical, and/or biological data that 2NDNATURE may not have Draft Trout Creek Characterization Plan and present to TAC Revise and finalize Characterization Plan Task 2. Trout Creek Characterization Instrument and maintain sites ‐ WY2010 Additional instrumentation and site maintenance ‐ WY2011 Evaluate sites using both rapid assessment and event‐based data collection Manage Database and data Task 3. Data Analysis and Water Quality Predictive Tool Integrate all relevant existing hydrologic, geomorphic, and water quality data from UTR and Trout Creek Conduct data analysis to provide a method to estimate the water quality benefit of distinct changes Task 4. Technical Report: Trout Creek Characterization and Quarterly Reporting Draft Technical Report/ present to TAC Revise and finalize Final Technical Report Quarterly progress reports/invoicing Day Due Date Due 90 11/18/09 150 210 270 635 690 690 1/17/10 3/18/10 5/17/10 5/17/11 7/11/11 7/11/11 690 7/11/11 690 7/11/11 840 900 12/8/11 2/6/12 ongoing