Spring Road Clearing

A rotary snow plow throws snow from a road lined by conifers
A rotary plow on the park highway in the Northwest Area of the park on April 3, 2019.

Road Clearing Process

Clearing the park highway is no quick or easy undertaking! Snow accumulates on the 30-mile park highway throughout the winter season (typically November through April). Snow depth can reach up to 30 feet at the highest elevations, with drifts occasionally reach as high as 40 feet. The highway may open in sections as conditions allow and as clearing operations continue. It will open to through traffic once it is safe for vehicles, not just only when it is cleared of snow. The road clearing process can take up to three months due to numerous factors including:

  • Heavy snowpack with deeper snowdrifts in some areas

  • Trees and boulders that have fallen across the road and been buried in the snow

  • Rockslides over the highway when the snow begins to melt

  • Snow avalanches over cleared sections of the highway

  • Snow storms (and additional accumulation) during the operations

  • Snow removal in parking areas

  • Road and road shoulder repairs

  • Lingering ice once snow is cleared
  • Equipment repair
Road clearing on Emerald side hill
Snow plowing below Emerald Lake

NPS Photo

When Will the Highway Open to Through Traffic?

Park road crew has completed snow clearing operations on the park highway. The highway opened to through traffic on Saturday, June 22, 2019 at 3:00 pm.

Snow removal from the park highway usually begins in April and continues for about two months before the road opens to through traffic. Predicting when the road will open is not possible, even in late spring, because weather in April and May can affect plowing progress significantly. See the chart below for opening and closing dates since 1980. The park highway encompasses 30 miles of stunning views through twisty hair pin corners, high elevations, and steep grades. The park highway traverses avalanche prone slopes with up to 2,000 foot drops and can hold a snowpack up to 40 feet deep.

Map of road clearing progress in the park
Map of road status, 6/22/19

2019 Road Clearing Operator Log

Log updates are posted when reports are received from operators in the field. The latest update may not reflect the current status. The road crew works Monday through Thursday, 10 hours per day.

June 22 - The Lassen National Park Highway (the main road that travels north/south through the park) is now entirely open to vehicle traffic for the summer season! Thanks to our road crew and Cal Trans District 2 for clearing the road ahead of schedule! Anticipate many snowy vistas while driving through the park.

June 14 - We punched through the last 1.5 miles of the park highway at 9:30 am yesterday. We swept almost to Summit Lake and blew through Summit Lake North Campground this afternoon. There is still 6 to 7 feet of snow in shaded areas. We will continue to work on the campgrounds next week and start hauling some equipment Monday morning. Once we get all the equipment down off the hill we will move on to Juniper lake. Thank you all for your support during road opening operations! It was a tough opening this season--the most intense and demanding season I’ve seen in my 8 years at Lassen. Thank goodness we had GPS this season; it saved us a few days of work and added to our safety and well-being.

June 6 - Today we ended our day just shy of the broken tree pullout, giving us a total mileage of 10.9 miles plowed. We are also finishing up clearing the rockfall and other debris along the section of highway between Sulphur Works and the Bumpass Hell parking area. There were two areas on the side of Diamond Peak where snow slides fell back onto the previously plowed road.

May 31 - Today we completed clearing to the switchbacks below the Lake Almanor Overlook. So far the snow depth has held pretty consistent at 16 to 18 feet! We were hoping that once we got past the Peak parking area there would be less snow, but it's looking like the snow depth probably won't start to lessen significantly until after we get past the Terrace Lake trailhead.

CalTrans blew out most of the snow from the Lassen Peak parking lot this week, but we will have to drop back in to do some more work with our loader in a couple weeks after the snow has melted a bit more.

Next week we will begin cleaning up all the rockslides, downed trees and brooming the road to the Bumpass Hell parking lot in preparation for opening the road to that point. We will also be digging out the bathroom so it can be serviced and prepped for visitors. Repairs were made to the big loader so we are back at full production again.

May 24 - It's been a tough couple of weeks dealing with the weather up on the hill, and we've gotten roughly 4 feet of new snow since Thursday of last week. The road is now cleared up to the Lassen Peak parking lot. We've spent the last four days stripping layers of snow from the lot, and we have it down enough for CalTrans to finish blowing it out. We have literally run out of room to
put the snow, so the parking lot is going to be a little smaller than normal for a while. Our big blower's loader lost all controls today due to a bad computer -- the replacement part is ordered, but still a few days out, so we will continue next week with just our small blower. Progress will be slow. We are hoping for a break in the weather!

May 16 - We made it to the beginning of the Lake Helen side hill yesterday, but visibility on that section of the road was too poor to work on that section of road today. Tomorrow we will work on the Warner Valley road into Drakesbad, and hopefully the weather will permit us to resume work on the main park highway on Monday.

May 15 - Previously opened sections of the park highway closed temporarily to vehicle traffic due to snow. The highway is currently closed beyond the Kohm Yah-mah-nee Visitor Center in the south and beyond the Loomis Museum in the north, but will reopen when conditions allow for safe travel.

May 10 - The park highway has opened to vehicle traffic one mile past the Kohm Yah-mah-nee Visitor Center to Sulphur Works. The road remains closed to vehicles beyond the Sulphur Works parking area.

May 8 - Road crew has cleared a total of 5.2 miles from the Kohm Yah-mah-nee Visitor Center. They are now next to Emerald Lake and working their way to the Bumpass Hell parking area. The snowdrift at the north end of Emerald Lake measured 28 feet high (photo)! The crew is expecting parts for the rotary blower next week, which will bring them back to full strength. Thank you to CalTrans, who is now assisting with snow clearing beyond the Devastated Area on the north side of the park.

May 5 - Upon resuming operations this week, we only cleared a tenth of a mile due to due to one of our blowers becoming non-functional. Road clearing will continue while the blower is being repaired. Going without this machine will delay progress a bit.

May 3 - We finished the day at the pullout just before the upper switchback east of Diamond Peak. We have cleared a total of 4.2 miles. We have Emerald sidehill in our sights and it looks deep! Staff also made an initial pass on Butte Lake road this week, but the road remains closed. Since it's a dirt road, we have to clear just above the roadbed and allow the remaining layer to melt and the road bed to dry.

April 25 - We are 2.5 miles up the highway from the Kohm Yah-mah-nee Visitor Center and 3/4 of the way across Diamond Peak sidehill. The drifts are deep!

April 23 - Completed initial pass of Sulphur Works parking area and cleared an additional half mile beyond Sulphur Works.

April 22 - We reached Sulphur Works parking area at the end of the shift today. We will begin clearing the park area on Tuesday, April 23, but it will take awhile to clear the restroom of snow.

April 18 - The highway opened to vehicles between Loomis Plaza and Devastated Area (10 miles). There is 4-6 feet of snow at the Devastated Area. Road clearing began today at the Southwest entrance! The snow is much deeper (~12 feet) than it is at Manzanita Lake to Devastated Area, so more machines are needed and the process of clearing will take much longer. Please stay clear of equipment. Operators may not be able to see you.

April 11 - The highway is cleared for approximately ten miles between the Loomis parking area and the Devastated Area parking lot. The highway remains closed to vehicles beyond the Loomis parking area.

April 2 - The highway is cleared approximately three miles from the Loomis Museum parking area. The highway remains closed to vehicles at the Loomis parking area.

March 28 - Snow clearing operations began on the park highway. Snow has been cleared from the Manzanita Lake Campground road and campground loops. The road remains closed to vehicles.


Spring Road Opening Dates - 1980 to Present


Date plowing began from southwest

Date road opened

April 1 Snow Depth at Lake Helen (8,000' elevation)

Date road closed

1980 April 20 May 29 231" / 19.3' November 21
1981 April 20 May 21 149" / 12.5' November 3
1982 April 19 June 18 266" / 22.2' October 25
1983 April 18 July 2 331" / 27.6' November 10
1984 April 23 June 4 175" / 14.6' October 28
1985 April 14 May 18 163" / 13.6' October 21
1986 April 7 June 7 195" / 16.3' November 24
1987 April 20 May 15 138" / 11.6' November 13
1988 April 2 May 20 98" / 8.2' November 7
1989 April 3 June 6 223" / 18.6' October 23
1990 April 1 April 28 106" / 8.9' November 14
1991 April 7 May 24 151" / 12.6' October 22
1992 April 6 May 14 127" / 10.6' October 29
1993 April 12 June 28 225" / 18.8' November 10
1994 April 3 May 20 101" / 8.4' November 7
1995 March 19 July 21 287" / 23.9' November 21
1996 April 1 June 12 171" / 14.3' October 18
1997 April 7 June 5 135" / 11.3' November 14
1998 April 5 July 12 250" / 20.9' November 10
1999 April 12 June 11 194" / 16.2' November 19
2000 April 3 June 2 178" / 14.9' November 17
2001 April 2 May 10 109" / 9.1' November 15
2002 April 1 May 22 166" / 13.9' November 13
2003 March 26 May 23 185" / 15.5' November 7
2004 March 11 May 27 187" / 15.6' October 28
2005 April 4 June 2 173" / 14.5' November 8
2006 April 3 July 6 266" / 22.2' November 11
2007 April 2 May 18 112" / 9.3' December 6
2008 March 31 May 18 132" / 11' December 12
2009 April 13 June 4 146" / 12.2' November 18
2010 April 19 July 8 169" / 14.1' October 23
2011 April 19 July 16 242" / 20.2' November 22
2012 April 21 June 1 145" / 12.1' November 19
2013 March 21 May 24 140" / 11.7' December 18
2014 April 3 May 19 122" / 10.2' December 1
2015 March 31 May 3 91" / 7.6' November 8
2016 April 18 June 12 199" / 16.6' October 30
2017 April 4 July 26 243" / 20.3' November 10
2018 March 30 May 27 131" / 11' November 20
2019 April 18 June 22 238" / 19.8' November 29

Last updated: November 30, 2019

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Mineral, CA 96063


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