HomeMy WebLinkAboutMemo - Read Before Packet - 08/12/2025 - 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 12, 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 (WNV)- Spray Notification
BOTTOM LINE
The Larimer County Department of Health and
Environment recommends that the City spray for
adult mosquitoes at this time. The treatment is
scheduled for Sunday, Aug. 17.
The treatment zone covers the central part of the city,
stretching from Mulberry Street to Harmony Road
and from Shields Street to Lemay Avenue. It also
extends east to Timberline Road between Mulberry
Street and Prospect Road.
The vector index (VI) in this area is 1.19, exceeding
2025 continues to be an interesting season. VDCI is
trapping fewer Culex mosquitoes than expected, but
their WNV infection rate is twice the normal level.
According to the Colorado Department of Health and
Environment, Larimer County currently leads the
state in cases and has six of the reported 24 cases-
as of Aug. 6.
2
WNV ACTIVITY ACROSS THE CITY
Week 32 of 37
Quadrant Previous Week VI Current VI Previous Week
Positive Traps
Current Week
Positive Traps
NW 0.32 0.39 3 2
NE 0.42 0.35 3 4
SE 0.25 0.42 4 5
SW 0.10 0.36 1 4
Citywide 0.28 0.40 11 15
Floating Zone NA*1.19**NA*7
*Floating zones vary in size and location and cannot be compared from week to week.**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
fcgov.com/westnile
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
NEXT STEPS
City staff will coordinate with Vector Disease Control
to implement spraying on Sunday, Aug. 17,weather permitting. Spraying will start at
dusk.
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