Herbicide Applications
Herbicide applications for county natural lands or rights-of-way.
| Start | End | Location | Open to the public | Product | Notes |
|---|---|---|---|---|---|
| 2025/09/0209/02/2025 | 2025/09/0409/04/2025 | Agricultural Heritage Center HWY 66 | Yes | Milestone | Spot spraying for Canada thistle. Agriculture Heritage Center is not open to the public these days. |
| 2025/08/2608/26/2025 | 2025/09/1209/12/2025 | Reynolds Ruth | Yes | Milestone, Telar XP | Spot spraying for eradication species Orange Hawkweed and yellow toadflax *EXTENDED 8/26 Due to weather |
| 2025/08/2608/26/2025 | 2025/09/1209/12/2025 | Grassy Top (North of Nederland) | Yes | Quinstar 4L | Spot spraying for eradication species leafy spurge *EXTENDED 8/26 Due to weather |
| 2025/08/2608/26/2025 | 2025/09/1209/12/2025 | Schmidt Trust (Gold Hill, Dixon Rd.) | Yes | Quinstar 4L, Milestone, Telar XP | Spot spraying for eradication species leafy spurge, spotted knapweed, common tansy, yellow toadflax *EXTENDED 8/26 Due to weather |
| 2025/08/2608/26/2025 | 2025/09/1209/12/2025 | OverBrook Trail | Yes | Quinstar 4L | Spot spraying for eradication species leafy spurge *EXTENDED 8/26 Due to weather |
| 2025/08/2608/26/2025 | 2025/09/1209/12/2025 | Kraft | Yes | Quinstar 4L | Spot spraying for eradication species leafy spurge *EXTENDED 8/26 Due to weather |
| 2025/08/2508/25/2025 | 2025/09/0409/04/2025 | Hall Ranch | Yes | Rejuvra | Broadcast spraying with Rejuvra for cheatgrass control. |
| 2025/08/2508/25/2025 | 2025/09/0409/04/2025 | Hall 2 | No | Rejuvra | Cheatgrass application with tractor. |
| 2025/08/2508/25/2025 | 2025/09/0409/04/2025 | Ron Stewart Preserve at Rabbit Mountain - Indian Mesa and Eagle Wind Trails | Yes | Rejuvra | Broadcast spraying with tractor for cheatgrass control. Watch for equipment near road and trails. |
| 2025/08/1808/18/2025 | 2025/08/2208/22/2025 | Boulder Canyon Trail | Yes | Milestone | Spot spraying for eradication species Japanese Knotweed, spotted knapweed and common tansy. *STARTED & COMPLETED 8/20 |
| 2025/08/1108/11/2025 | 2025/08/1408/14/2025 | Lagerman Agricultural Preserve - Open Sky Loop from Link trail East to 75th st. | Yes | Milestone, Telar XP | Spot spraying for listed weed species canada thistle, musk thistle, scotch thistle, common teasel, common mullein, chicory, dalmatian toadflax. |
| 2025/08/1108/11/2025 | 2025/08/1508/15/2025 | Betasso Preserve Open Space - Canyon Loop trail, Betasso Link trail, Blanchard trail | Yes | Milestone, Telar XP | Spot spraying for listed weed species canada thistle, musk thistle, common mullein, st. johnswort, poison hemlock, diffuse knapweed. |
| 2025/08/1108/11/2025 | 2025/09/0409/04/2025 | Prescott | No | Milestone | Treatment of Canada thistle in fen restoration area. *STARTED 8/13 *EXTENDED 8/13 *EXTENDED 8/21 DUE TO WEATHER |
| 2025/08/1908/19/2025 | 2025/08/1908/19/2025 | Nederland Sort Yard and Transfer Station | Yes | Milestone, Telar XP | Spot spraying for eradication species oxeye daisy and scentless chamomile *STARTED AND COMPLETED 8/21 |
| 2025/08/1808/18/2025 | 2025/08/2908/29/2025 | CR 126, CR 128, Ridge Rd., | Yes | Milestone, Telar XP | Spot spraying for eradication species oxeye daisy, yellow toadflax, scentless chamomile *STARTED 8/19 *COMPLETED 8/21 |
| 2025/08/1808/18/2025 | 2025/08/2908/29/2025 | Mud Lake -Caribou Ranch Link, Kinnickinnick Loop, Tungsten Loop, Chickadee Trail, Sherwood Forest Trail | Yes | Milestone, Telar XP | Spot spraying for listed noxious weed species *STARTED 8/18 *COMPLETED 8/21 |
| 2025/08/1808/18/2025 | 2025/08/2908/29/2025 | Caribou Ranch - Blue Bird Loop, DeLonde Trail | Yes | Telar XP | Spot spraying for listed noxious weed species *STARTED 8/18 *COMPLETED 8/21 |
| 2025/08/1208/12/2025 | 2025/08/2208/22/2025 | Pierce | No | Ecomazapyr 2SL, Clearcast | Spot spraying for eradication species hairy willowherb and purple loosestrife *STARTED & COMPLETED 8/15 |
| 2025/08/1208/12/2025 | 2025/09/1209/12/2025 | Hodgson Harris Reservoir | Yes | Ecomazapyr 2SL, Clearcast | Spot spraying for eradication species hairy willowherb *EXTENDED 8/21 due to staff capacity *UPDATE - will also be spot spraying for leafy spurge with Quinstar 4L |
| 2025/08/1208/12/2025 | 2025/08/2208/22/2025 | Flagg Park | Yes | Ecomazapyr 2SL, Clearcast | Spot spraying for eradication species hairy willowherb *CANCLED 8/21 |
| 2025/08/1208/12/2025 | 2025/08/2208/22/2025 | Heil Valley Ranch | Yes | Ecomazapyr 2SL, Clearcast | Spot spraying for eradication species hairy willowherb *STARTED AND COMPLETED 8/22 |
| 2025/08/0508/05/2025 | 2025/09/1209/12/2025 | Link Trail., Lagerman Reservoir and AHI Longmont Farms | Yes | Ecomazapyr 2SL, Clearcast | Spot spraying for eradication species hairy willowherb *STARTED 8/15 *EXTENDED 8/15 *EXTENDED 8/21 due to raptor closure |
| 2025/08/0608/06/2025 | 2025/08/1508/15/2025 | St Vrain Rd., Nelson Rd., Prospect Rd., 63rd St., 75th St | Yes | Ecomazapyr 2SL, Clearcast | Spot spraying for eradication species hairy willowherb *STARTED & COMPLETED* 8/7/25 |
| 2025/08/0808/08/2025 | 2025/08/0808/08/2025 | Hyw 119, Dixon Rd, Gold Hill Rd, Sunshine Canyon Dr, Lefthand Canyon Dr, Nelson Rd | Yes | Milestone | Spot spraying County and State roadsides for List A eradication species (Spotted Knapweed, Japanese Knotweed, Yellow Toadflax) and other listed species. *COMPLETED |
| 2025/08/0808/08/2025 | 2025/08/0808/08/2025 | Boulder Canyon Dr | Yes | Ecomazapyr 2SL | Spot spraying State HWY for eradication species Japanese Knotweed *COMPLETED |
| 2025/07/2807/28/2025 | 2025/08/0108/01/2025 | Caribou Ranch - Sherwood Gulch | Yes | Milestone | Spot spraying for listed species within the planned Sherwood Creek project site *COMPLETED 7/30/2025 |
| 2025/07/2807/28/2025 | 2025/08/0108/01/2025 | Heil Valley Ranch | Yes | Quinstar 4L | Spot spraying for eradication species leafy spurge. *COMPLETED 7/30/2025 |
| 2025/07/2107/21/2025 | 2025/07/2407/24/2025 | Agricultural Heritage Center | Yes | Escort XP Dupont, Vista XRT, Sulfentrazone | Spot spraying for listed weed species Whitetop and kochia. *only spot sprayed Escort XP for whitetop, no other herbicide used. |
| 2025/07/2107/21/2025 | 2025/07/2407/24/2025 | Lagerman Agricultural Preserve on the Open Sky Loop | Yes | Milestone, Escort XP Dupont | Spot spraying for listed weed species Canada thistle, musk thistle, common tansy, common teasel. *Correction* Herbicides used - Milestone and Telar XP |
| 2025/07/2207/22/2025 | 2025/07/2507/25/2025 | Meeker Sort Yard | Yes | Milestone | Spot spraying for eradication species meadow hawkweed *COMPLETED 7/22 |
| 2025/07/2207/22/2025 | 2025/08/2208/22/2025 | Dake (off Sugarloaf Rd.) | Yes | Milestone | Spraying for eradication species common tansy *RESCHEDULED 7/22 due to plant phenology - not yet flowering *CORRECTION Telar XP will also be used *COMPLETED 8/21 |
| 2025/07/2207/22/2025 | 2025/07/2507/25/2025 | Walden Ponds | Yes | Ecomazapyr 2SL | Spot spraying for eradication species garden loosestrife *COMPLETED 7/24 |
| 2025/07/2207/22/2025 | 2025/07/2507/25/2025 | Walden Ponds | Yes | Telar XP | Spot spraying for eradication species yellow toadflax *COMPLETED 7/25/2025 |
| 2025/07/1807/18/2025 | 2025/07/1807/18/2025 | Kraft | Yes | Quinstar 4L | Spot spraying for eradication species leafy spurge *Canceled due to weather conditions |
| 2025/07/1707/17/2025 | 2025/07/1707/17/2025 | Sugarloaf Rd., Sugarloaf Mountain Rd., Sunshine Canyon Dr., HWY 72 | Yes | Quinstar 4L | Spot spraying for eradication species spotted knapweed *Correction - chemicals used will be Milestone, Tordon 22k, Rejuvra *Completed 7/17/2025 |
| 2025/07/1407/14/2025 | 2025/07/1807/18/2025 | Heil Valley Ranch | Yes | Quinstar 4L, Tordon, Milestone, Rejuvra | Spot Spraying for Listed Species: Leafy Spurge, Knapweed, Jointed Goat Grass *Completed 7/17/2025 *Note - Joined goat grass control was not completed and will be done later |
| 2025/06/3006/30/2025 | 2025/07/0307/03/2025 | South Boulder Rd, Valmont Rd, Airport Rd | Yes | Plainview SC, Vista XRT, Chlorsulfuron 75 | Spray treatment of Road Medians for safety and infrastructure integrity. *COMPLETED* 7/3 |
| 2025/06/2306/23/2025 | 2025/07/1807/18/2025 | OverBrook Trail | Yes | Quinstar 4L | Spot Spraying for eradication species Leafy Spurge *Canceled due to weather conditions |
| 2025/06/2306/23/2025 | 2025/07/1807/18/2025 | OverBrook Trail | Yes | Milestone | Spot Spraying for eradication species Russian Knapweed *Completed 7/11 |
| 2025/06/2306/23/2025 | 2025/06/2606/26/2025 | Mayhoffer Singletree Trail | Yes | Milestone, Telar XP | NOTE: IN PROGRESS Knapweed, scotch thistle, hoary cress, musk thistle, canada thistle. Spot spraying for noxious weed suppression. |
| 2025/06/2306/23/2025 | 2025/06/2606/26/2025 | Schoolhouse Loop at Heil Valley Ranch | Yes | Milestone, Telar XP | NOTE: POSTPONED Poison hemlock, musk thistle, canada thistle. Spot spraying for noxious weed suppression. |
| 2025/06/1106/11/2025 | 2025/06/1106/11/2025 | South Boulder Rd | Yes | Plainview SC | Median spraying in conjunction with Road Maintenance for infrastructure safety. *COMPLETED* 6/11 |
| 2025/06/0206/02/2025 | 2025/06/0606/06/2025 | Carolyn Holmberg Preserve at Rock Creek Farm | Yes | Ecomazapyr 2SL | The Boulder County Agricultural Division will be doing a dam infrastructure protection treatment at Stearns Lake. *COMPLETED 6/4/2023 |
| 2025/06/0406/04/2025 | 2025/06/2006/20/2025 | Heil Valley Ranch | Yes | Quinstar 4L | Spot spraying for eradication species Leafy Spurge. Application will occur during the morning and be finished before 10 am. *RESCHEDULED 6/4 due to weather *RESCHEDULED 6/10 due to staff capacity *COMPLETED 6/18 |
| 2025/06/0206/02/2025 | 2025/06/0506/05/2025 | Mayhoffer (Superior) - Coalton and Meadowlark trails | Yes | telar, milestone, vista | Spot spraying from truck-mounted sprayer to treat curly dock, thistles, diffuse knapweed. |
| 2025/05/3005/30/2025 | 2025/05/3005/30/2025 | Boulder County Fairgrounds | Yes | Plainview SC & Quinstar 4L | Treatment of weeds around demonstration plot infrastructure and walkways. *COMPLETED* 5/30 |
| 2025/05/2705/27/2025 | 2025/05/3005/30/2025 | Boulder County ROW | Yes | Milestone | Spot spraying for eradication species: Russian Knapweed *COMPLETED* 5/30 |
| 2025/05/3005/30/2025 | 2025/06/1306/13/2025 | OverBrook Trail | Yes | Quinstar 4L | Spot spraying for eradication species: Leafy Spurge *RESCHEDULED 5/30 due to staff capacity *CANCELED 6/13 due to staff capacity |
| 2025/05/1205/12/2025 | 2025/05/1505/15/2025 | Hall Ranch 2 | No | Milestone and Telar | Treating diffuse knapweed, dalmatian toadflax, houndstongue, thistles, burdock, hoary cress, flixweed, sulfur cinquefoil |
| 2025/05/1605/16/2025 | 2025/05/1605/16/2025 | Boulder County ROW | Yes | Tordon 22K | Spot spraying for eradication species: Russian Knapweed *STARTED & COMPLETED* 5/16 |
| 2025/05/1605/16/2025 | 2025/05/3005/30/2025 | Boulder County and State Highway ROW | Yes | Quinstar 4L | Spot spraying for eradication species: Leafy Spurge *STARTED* 5/16 *EXTENDED* 5/16 *COMPLETED* 5/30 |
| 2025/05/0705/07/2025 | 2025/05/3005/30/2025 | Spring Valley Rd (Boulder) | Yes | Ecomazapyr | Cut stump treatment of Russian Olives on roadside for driver and road safety. *RESCHEDULED* 5/7 due to weather. *RESCHEDULED* 5/14 due to staff capacity. *RESCHEDULED* 5/22 due to staff capacity. |
| 2025/05/0505/05/2025 | 2025/06/0506/05/2025 | Monarch Park - Niwot Trails | Yes | telar, milestone, vista | Touch up spray treatment of curly dock, teasel, prickly lettuce, thistles to maintain integrity of ecological restoration project. *EXTENDED* 5/8 due to weather *STARTED* 5/14 *ESTENDED* 5/15 due to weather *EXTENDED* 5/29 due to weather |
| 2025/04/2804/28/2025 | 2025/05/0105/01/2025 | Agricultural Heritage Center HWY 66 | Yes | Ecomazapyr | Cut stump application to tree near building foundation to prevent tree/tree roots from damaging infrastructure. COMPLETED 05/01/2025 |
| 2025/04/2804/28/2025 | 2025/05/2305/23/2025 | Tommy Thompson - Rock Creek Trail | Yes | Telar and Vista | Spray treatment of curly dock, teasel, kochia, thistles, hoary cress for suppression *STARTED* 4/29 *POSTPONED* 5/8 due to weather *COMPLETED* 5/14 |
| 2025/05/2805/28/2025 | 2025/05/2305/23/2025 | Ruth Roberts - Ruth Roberts Connector Trail | Yes | Telar and Vista | Spraying treatment of curly dock, teasel, kochia, thistles, hoary cress for supression *POSTPONED* 5/1 due to staff capacity *POSTPONED* 5/8 due to weather *POSTPONED* 5/15 due to weather *CANCELED* 5/29 due to staff capacity |
| 2025/04/2104/21/2025 | 2025/04/2404/24/2025 | Monarch Park | Yes | Telar and Vista | Spraying for curly dock, teasel, musk thistle. *COMPLETED 4/23/25* |
| 2025/04/1404/14/2025 | 2025/04/1704/17/2025 | Hall Meadows | No | Transline | Application to control diffuse knapweed and increase the biodiversity of a restoration site. |
| 2025/04/1004/10/2025 | 2025/04/1004/10/2025 | Cemex Stone Canyon Property | No | Transline | Early season treatment for Diffuse Knapweed to enhance biodiversity and preserve significant natural communities. *Rescheduled from 4/8 to 4/10. *Completed on 4/10 |
| 2025/04/0704/07/2025 | 2025/04/1004/10/2025 | Golden Fredstrom (Near St. Vrain Rd and 75th St.) | No | Telar - 1.5 oz/acre, milestone - 5 oz/acre | Application to control teasel, houndstongue, Canada thistle, bull thistle, common mullein, diffuse knapweed. Completed on 4/10/2025 |
| 2025/04/0704/07/2025 | 2025/04/1104/11/2025 | Carolyn Holmberg Preserve at Rock Creek Farm | Yes | Imazpyr | Stump applications around historical buildings. *Started & Completed on 4/9/25 |
Mowing Reports
Mowing activities are recorded for Boulder County maintained roads.
| Start | End | Location | Notes |
|---|---|---|---|
| 2025/08/2508/25/2025 | 2025/08/2608/26/2025 | Valmont Rd, Isabelle Rd, 95th St, 75th St, Jay Rd | These Roads are being mowed as part of our general county roadside mowing routes for vehicle, cycling, pedestrian and wildlife safety. |
| 2025/08/0408/04/2025 | 2025/08/0508/05/2025 | County Roads North of Hwy 66 between East Countyline Rd and 75th St. | These Roads are being mowed as part of our general county roadside mowing routes for vehicle, cycling, pedestrian and wildlife safety. |
| 2025/06/2506/25/2025 | 2025/06/2606/26/2025 | Ogallala, Jasper Rd, 119th St & Arapahoe, Lakota, Isabelle Rd, Oxford Rd, Niwot Rd, Lookout Rd. 63rd St., Blue Mountain Rd, Apple Valley Rd, N 55th St | These Roads are being mowed as part of our general county roadside mowing routes for vehicle, cycling, pedestrian and wildlife safety. |
| 2025/06/2306/23/2025 | 2025/06/2406/24/2025 | East County Line Rd, Kenosha Rd, N 115th St., 109th St., Roads West of Niwot (Oxford Rd., Nimbus Rd., Nebo Rd., Plateau Rd., 39th St., 41st St., 49th St., 77th St.) | These Roads are being mowed as part of our general county roadside mowing routes for vehicle, cycling, pedestrian and wildlife safety. |
| 2025/06/1806/18/2025 | 2025/06/1806/18/2025 | 95th from south of Plateau, Isabelle rd., | BC road of way safety. Be beware of grass clippings on road. |
| 2025/06/1606/16/2025 | 2025/06/1706/17/2025 | 65th St. North of Nelson Rd., Plateau Rd. near Lagerman res, 55th St./Ouray - South of Nelson Rd., East County Line Rd. - south of HWY 66, N 119th St., Prospect Rd., Pipit Rd., Oxford Rd. - East of US 287 | Boulder County ROW Roadside safety operations |
| 2025/06/1206/12/2025 | 2025/06/1206/12/2025 | St. Vrain Rd, All road between Hygiene Rd and Nelson RD (49th ST, 51 ST, 59th ST, 65th ST, Crane Hollow RD) | These Roads are being mowed as part of our general county roadside mowing routes for vehicle, cycling, pedestrian and wildlife safety. |
| 2025/06/0406/04/2025 | 2025/06/0506/05/2025 | 63rd Street from Nelson to Diagonal (119); Niwot/Neva Road to Highway 36, 63rd Street to Highway 36. | These Roads are being mowed as part of our general county roadside mowing routes for vehicle, cycling, pedestrian and wildlife safety. |
| 2025/06/0206/02/2025 | 2025/06/0406/04/2025 | Boulder County ROW in both the north and south part of the county | 119th and Arapahoe Rd, Flagg, Dillon RD. 75th, 87th, 95th, and Woodland north of State Highway 66. |
| 2025/05/2805/28/2025 | 2025/05/2905/29/2025 | Boulder County Maintained Roads between Boulder and Louisville and between Erie and Lafayette | Cherryvail Rd, Marshall Rd, S 66th St., 76th St, South Boulder Rd, Dillon Rd, Jasper Rd, 119th and Arapahoe. |
| 2025/05/1905/19/2025 | 2025/05/2205/22/2025 | East Boulder County. South of HWY 52 & Niwot Rd. | |
| 2025/04/2804/28/2025 | 2025/05/0205/02/2025 | County Maintained roads North of State Highway 66 Between 75th St and East County Line Road. |
Drone Applications
You can sign up to receive email or text notifications about scheduled drone herbicide applications on non-agricultural open space areas. Notifications will be sent out on the Friday before the week of application. Drones may be used in areas where the terrain is too steep for worker safety, tractors cannot operate safely, or the area is too large for other methods to be practical. They are also ideal for smaller, remote applications in places that are otherwise inaccessible. To ensure safety, drones are operated at least 50 feet away from property boundaries and a minimum of 660 feet (1/8 of a mile) from residential areas and municipal boundaries.
| Start | End | Location | Open to the public | Product | Notes | Map |
|---|---|---|---|---|---|---|
| 2025/05/1905/19/2025 | 2025/05/2305/23/2025 | Hall Ranch Quarry Site | No | Milestone | A drone herbicide application will be conducted during this timeframe by the managing contractors to fulfill state requirements for mine reclamation at the Hall Quarry Site before management of the site is transferred to Boulder County control. A drone application is preferred over other application methods for personnel safety and because drones operate 20 feet or less from the ground, move at slower speeds and in patterns, and can be programed to spray small, specific areas. | View Map |