U.S. Department of the Interior

U.S. Geological Survey

Organic Drift Studies dur2005Theodore Kennedy & Scott WrightGCMRC
Outline

 Background Objectives Methods Results Conclusions Future work—using hydroacoust

monitor organic drift
Background

 Rainbow trout and humpback chu

feeders
Background

 Rainbow trout and humpback chu

feeders

 Rates of Cladophora and midge d

positively correlated
Background

 Rainbow trout and humpback chu

feeders

 Rates of Cladophora and midge d

positively correlated

 Therefore, higher amounts of org

should = more food
Background

Type Typical 

Concentration (mg/l)

What is it? Wher

it comfrom?

Mostly algae, some aq. veg., a few inverts

Glen CanyReacLake Lake 

Plankton, tiny bits of detritus, etc.Carbs, fatty acids, humicacids, etc.

Coarse Organic Matter>1 mm

~0.04

Fine Organic Matter>0.001 mm

~0.4

Dissolved Organic Matter <.001 mm

~4
Hydrograph
Objectives

 Determine whether organic drift d

low fluctuations relative to steady 

 Previous research indicates:

 Drift is low during steady flows and high

fluctuating flows (Leibfried and Blinn 19

 Seasonality of drift is unclear (McKinney 

Leibfried and Blinn 1987, Shannon et al 

 Test feasibility of using acoustics 

organic drift
Methods

 Data collection

 Two different plankton nets used—0

& 1mm mesh

 Nets equipped with flow meter at the

Vertically and width integrated samp

 Processing

 Subset of samples sorted (algae, aq

invertebrates, plankton), weighed, b

 Other samples just weighed and bur
Is There a Relationship Betwee

Discharge and Concentration?
Antecedent Conditions and Dis

Affect Organic Concentrations
Is it Just More Concentrate
Results Time Avg

Conc. (mg/l)

August 2005*

0.0099

Sept 2005Fluctuate*

0.027

Sept 2005 Steady

0.033

Oct 2005 Steady

0.0092

Oct 2005 Fluctuate

0.044

May 2006* 0.026

*= Load calculated based on rating curve
Results Time Avg

Conc. (mg/l)

Discharge Range (cfs)

August 2005*

0.0099 11,000-

18,5006,750-9,0508,210-8,5006,950-9,310

Oct 2005 Steady

0.0092 8,640-8,720

6,900-12,100

Sept 2005Fluctuate*

0.027

Sept 2005 Steady

0.033

Oct 2005 Fluctuate

0.044

May 2006* 0.026

*= Load calculated based on rating curve
Results Time Avg

Conc. (mg/l)

Discharge Range (cfs)11,000-18,5006,750-9,0508,210-8,5006,950-9,310

Oct 2005 Steady

0.0092 8,640-8,720

6,900-12,100

August 2005*

0.0099

Sept 2005Fluctuate*

0.027

Sept 2005 Steady

0.033

Oct 2005 Fluctuate

0.044

May 2006* 0.026

*= Load calculated based on rating curve
Results Time Avg

Conc. (mg/l)

Discharge Range (cfs)11,000-18,5006,750-9,0508,210-8,5006,950-9,310

Oct 2005 Steady

0.0092 8,640-8,720 

6,900-12,100

August 2005*

0.0099 

Sept 2005Fluctuate*

0.027 

Sept 2005 Steady

0.033 

Oct 2005 Fluctuate

0.044 

May 2006* 0.026 

*= Load calculated based on rating curve
Conclusions

 Antecedent Conditions have a La

on Drift Concentration than Fluct

 What determines antecedent con

 Seasonality of algae growth? Lower flows led to desiccation and e

Cladophora growing between 7-9k s

 Lower fluctuations allowed for highe

algae growth?
What makes for good fishin
Using Acoustics to Monitor 
Backscatter is a Predictor of Fi

Organics

0.000.010.101.00

40 45 50 55 

Acoustic backscatter (dB

Concentration of organics (mg/L) 

late October

early October