HomeMy WebLinkAboutMemo - Read Before Packet - 08/05/2025 - Memorandum from Ryan Vincent re West Nile Virus – Spray NotificationNatural Areas Department
1745 Hoffman Mill Road
PO Box 580, Fort Collins, CO 80522
970-416-2493
rvincent@fcgov.com
CC: Dean Klingner, Community Services Director; Mike Calhoon, Parks Director; Katie Donahue, Natural Areas
Director; Matt Parker, Natural Areas Ecological Stewardship Manager 1
MEMORANDUM
Date: August 5, 2025
To: Mayor and City Councilmembers
Through: Kelly DiMartino, City Manager
Tyler Marr, Deputy City Manager
From: Ryan Vincent, Natural Areas Sr. Supervisor
Subject: West Nile Virus – Spray Notification
BOTTOM LINE
The Larimer County Department of Health and Environment
recommends that the City spray for adult mosquitoes on
Thursday, Aug. 7.
Data from the trapping network indicate a rebound of West Nile
Virus (WNV) activity.
The treatment zone covers parts of the northeast and southeast
quadrants, specifically between Prospect Road and Carpenter
Road, and between Timberline Road and I-25. The vector index
(VI) in this area is 0.88, exceeding the City’s policy threshold of
0.75.
INSIDE THE DATA
This week 11 mosquito traps tested positive, up from last week’s
count of seven, with detections across all four quadrants. This
week’s treatment focuses on the highest risk area and covers five
of the 11 current positive trap locations.
Infection rates, although lower than two weeks ago (and prior to
the two previous treatments), continue to drive vector indexes values. The current infection
rates are not typically seen until about a month later in the season.
Docusign Envelope ID: EF31C2E6-FE2A-4DAB-930D-AD4F200F0EB9
2
WNV ACTIVITY ACROSS THE CITY
Week 31 of 37
Quadrant Previous Week VI Current VI Previous Week
Positive Traps
Current Week
Positive Traps
NW 0.11 0.32 1 3
NE 0.23 0.42 2 3
SE 0.16 0.25 3 4
SW 0.09 0.1 1 1
Citywide 0.16 0.28 7 11
Floating Zone NA 0.88* NA 5
*VI Threshold for spraying in a floating zone is 0.75.
WNV ACTIVITY COMPARED TO HISTORICAL AVERAGES
Abundance of Culex mosquitoes (the carriers of WNV) remains below average. However, the
higher-than-normal infection rate is elevating the vector index.
OUTREACH EFFORTS TO INFORM RESIDENTS
• The City will post spray information for the community on fcgov.com/westnile and on its
social media accounts. Community members who signed up through NOCO Alert will
also receive notifications.
• Community members can track the progress of spray vehicles in real time using GPS on
the City’s West Nile Virus website.
NEXT STEPS
• City staff will coordinate with Vector Disease Control International, the City’s contractor,
to implement spraying on Thursday, Aug. 7, weather permitting. Spraying will start at
dusk.
###
Docusign Envelope ID: EF31C2E6-FE2A-4DAB-930D-AD4F200F0EB9
Natural Areas Department
1745 Hoffman Mill Road
PO Box 580, Fort Collins, CO 80522
970-416-2493
rvincent@fcgov.com
CC: Dean Klingner, Community Services Director; Mike Calhoon, Parks Director; Katie Donahue, Natural Areas
Director; Matt Parker, Natural Areas Ecological Stewardship Manager 1
MEMORANDUM
Date: August 5, 2025
To: Mayor and City Councilmembers
Through: Kelly DiMartino, City Manager
Tyler Marr, Deputy City Manager
From: Ryan Vincent, Natural Areas Sr. Supervisor
Subject: West Nile Virus – Spray Notification
BOTTOM LINE
The Larimer County Department of Health and Environment
recommends that the City spray for adult mosquitoes on
Thursday, Aug. 7.
Data from the trapping network indicate a rebound of West Nile
Virus (WNV) activity.
The treatment zone covers parts of the northeast and southeast
quadrants, specifically between Prospect Road and Carpenter
Road, and between Timberline Road and I-25. The vector index
(VI) in this area is 0.88, exceeding the City’s policy threshold of
0.75.
INSIDE THE DATA
This week 11 mosquito traps tested positive, up from last week’s
count of seven, with detections across all four quadrants. This
week’s treatment focuses on the highest risk area and covers five
of the 11 current positive trap locations.
Infection rates, although lower than two weeks ago (and prior to
the two previous treatments), continue to drive vector indexes values. The current infection
rates are not typically seen until about a month later in the season.
Docusign Envelope ID: EF31C2E6-FE2A-4DAB-930D-AD4F200F0EB9
2
WNV ACTIVITY ACROSS THE CITY
Week 31 of 37
Quadrant Previous Week VI Current VI Previous Week
Positive Traps
Current Week
Positive Traps
NW 0.11 0.32 1 3
NE 0.23 0.42 2 3
SE 0.16 0.25 3 4
SW 0.09 0.1 1 1
Citywide 0.16 0.28 7 11
Floating Zone NA 0.88* NA 5
*VI Threshold for spraying in a floating zone is 0.75.
WNV ACTIVITY COMPARED TO HISTORICAL AVERAGES
Abundance of Culex mosquitoes (the carriers of WNV) remains below average. However, the
higher-than-normal infection rate is elevating the vector index.
OUTREACH EFFORTS TO INFORM RESIDENTS
• The City will post spray information for the community on fcgov.com/westnile and on its
social media accounts. Community members who signed up through NOCO Alert will
also receive notifications.
• Community members can track the progress of spray vehicles in real time using GPS on
the City’s West Nile Virus website.
NEXT STEPS
• City staff will coordinate with Vector Disease Control International, the City’s contractor,
to implement spraying on Thursday, Aug. 7, weather permitting. Spraying will start at
dusk.
###
Docusign Envelope ID: EF31C2E6-FE2A-4DAB-930D-AD4F200F0EB9