Glen Canyon Reach – 

Glen Canyon NRA 

Update 

• Water Temperature

• Electrofishing

• Netting
Glen Canyon Reach – Glen Canyon NRA 

Lees Ferry 

Glen Canyon Dam 

Slough 
Water Temperature 

Glen Canyon Dam 
Historic and Current Water Temperature 

Lees Ferry 

Water Temperature (oC) 

4 

6 

8 

10 

12 

14 

16 

18 

20 

22 

Daily Average Water Temperature of Colorado River at Lees Ferry, AZ- 09380000 

1-Jan 7-Jan 

13-Jan 19-Jan 25-Jan 31-Jan 

6-Feb 

12-Feb 18-Feb 24-Feb 

2-Mar 8-Mar 

14-Mar 20-Mar 26-Mar 

1-Apr 7-Apr 

13-Apr 19-Apr 25-Apr 

1-May 7-May 

13-May 19-May 25-May 31-May 

6-Jun 

12-Jun 18-Jun 24-Jun 30-Jun 

6-Jul 

12-Jul 18-Jul 24-Jul 30-Jul 5-Aug 

11-Aug 17-Aug 23-Aug 29-Aug 

4-Sep 

10-Sep 16-Sep 22-Sep 28-Sep 

4-Oct 

10-Oct 16-Oct 22-Oct 28-Oct 

3-Nov 9-Nov 

15-Nov 21-Nov 27-Nov 

3-Dec 9-Dec 

15-Dec 21-Dec 27-Dec 

2010 2022 2023 
Electrofishing Effort - 2023 

Reach 2 Reach 1 

Reach 3 
GLCA Sampling 2023 Number Times Sampled 

Sample Trips / Reach 

9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

A B C D E F G H 

Reach 

Electrofishing 

Netting(Slough) 

Chemical Treatment 
Electrofishing 

Smallmouth Bass 

Number of Fish 

Smallmouth Bass Length Frequency 

30 

n = 141 

12 SMB > 300mm 25 

0

20406080

100120140160180200220240260280300320 340360 

5 

380 

0 

400 

20 

15 

10 

Length (mm) 

Number of SMB / Reach 

45 

n = 141 

40

35 

A B C D E F G H

5 

0 

Number of Fish 30 

25 

20 

15 

10 

Reach 
Green Sunfish Length Frequency 

600 

n - 2086 

500 

Number of Fish 400 

300 

200 

100 

0 

0

102030405060708090

100 110 120 130 140 150 160 170 180 190 200 

Length (mm) 

Number of GSF / Reach 

800 

n = 2086 

700 

600 

A B C D E F G H 

Number of Fish 500 

400 

300 

200 

100 

0 

Reach 

Electrofishing 

Green Sunfish 
2 

Number of Fish 

Walleye Length Frequency 

3.5 

n = 21 

3 

2.5 

0

306090

120150180210240270300330360390420450 480 

1 

510 

0.5 

540 570 

0 

600 

1.5 

Length (mm) 

Number of Walleye / Reach 

14

12 

10 

n = 21 

A B C D E F G H

4 

2

0 

Number of Fish 

8 

6 

Reach 

Electrofishing 

Walleye 
Electrofishing Totals 

GLCA Sampling 

Species Fish Count 

Common Carp 17 

Green Sunfish 3042 

Bluegill 162 

Smallmouth Bass 141 

Largemouth Bass 2 

Black Crappie 1 

Walleye 21 

Stripe Bass 1 

Brown Trout 420 

Rainbow Trout 51 
Electrofishing Totals 

GLCA Sampling 

Months Oct 

Date (Multiple Items) 

Row Labels Sum of Count 

BGS 29 

BKC 1 

BNT 14 

GSF 1380 

NFC 13 

RBT 4 

SMB 57 

WAL 2 

Grand Total 1500 

Date (Multiple Items) 

Species Code SMB 

Reach Sum of Count 

A 10 

B 7 

C 19 

D 8 

E 10 

G 3 

Grand Total 57 
Fyke Nets –Slough 
 

 

Slough Fish Totals (Netting) 

June – July 2023 

Total Species and Number of Fish Sampled From the Slough 2023 

Species Upper Slough Lower Slough Totals 

Common Carp 285 7708 7,993 

Green Sunfish 1487 2010 3,497 

Bluegill 23 70 93 

Smallmouth Bass 36 631 667 

Brown Trout 0 9 9 

Bonytail? 1 0 1 

Walleye 0 3 3 

Gizzard Shad 0 2 2 

Channel Catfish 0 2 2 

Stripe Bass 0 1 1 

Released 

Flannelmouth Sucker 0 214 214 

Rainbow Trout 0 92 92 
Support/Funding FY 23 

Funding (GLCA/GRCA) 

BOR $300,000 

DS 22 $250,000 

Field Support 

USFWS 

GRCA 

Technical Support 

USGS GCMRC 
GLCA FY 24 Plans 

• GLCA Received Additional Funding – Disaster Supplement 23 Funds 

• 5-Years funds GLCA/GRCA 

• Purchase 2 additional electrofishing boats and a processing boat 

• GLCA Hires 

• 2 Additional Fish Biologist (5-Year Term) 

• 2 Fisheries Technician (5-Year Term) 

• 2 Fisheries Summer Seasonals