The significant -- and, in some places, catastrophic -- damage last week's flooding caused to roads and other transportation infrastructure around Boulder County is apparent.

As waters have receded and officials have begun assessing roadways, the city and county have identified several areas that will require extensive repairs.

The city is maintaining an updated list of closed roads and paths in and around Boulder at boulderfloodinfo.net. As of Thursday afternoon, there were 26 areas on the list, with city officials cautioning that it could grow longer as crews continue inspecting areas still under water.

"We're still very much in the assessment stage in terms of the transportation system," Boulder public works spokesman Mike Banuelos said. "We really are in some cases still responding to the emergency."

Banuelos highlighted some roads that suffered heavy damage and are likely to be closed for weeks while they undergo major reconstruction.

They are:

Seventh Street between Pennsylvania and University avenues;

Pennsylvania Avenue west of Seventh Street;

Willowbrook Road north of Cascade Avenue;

Cypress Drive at 55th Street;

King Avenue between 17th and 18th streets; and

The 1600 block of Mariposa Avenue.

The city has not released any estimates of how much the transportation repairs might cost.

Boulder County officials said Thursday they were working on a similar list of flood-ravaged streets, having already done emergency roadwork to establish at least temporary connections to cut-off areas like Jamestown, Lee Hill and Olde Stage Road.

The county is now focused on providing access to still-isolated areas, such as Fourmile Canyon and Lefthand Canyon. The work will require building entirely new roads in place of previous roadways wiped off the map in the flooding.

"The damage has been so significant that our commuting and recreational patterns have been changed dramatically, and we ask that the community be patient as we work to restore access and infrastructure over the next months and years," George Gerstle, Boulder County transportation director, said in a news release.

The county provided the following updates on damaged roads and access ways:

Boulder Canyon is closed indefinitely.

Flagstaff Road is damaged from Gregory Canyon Road to Panorama Point and is down to one lane, controlled by cones and a one-way traffic light. Access is limited to residents and businesses.

95th Street between Valmont and Lookout roads is closed.

West of Broadway, the only north-south access between Estes Park to the north and Interstate 70 to the south is the Peak to Peak Highway.

The only east-west route from the Peak to Peak to Boulder is Sunshine Canyon. Access to Sunshine Canyon is limited to local residents, utilities and contractors with verifiable business with residential homes or businesses.

Numerous other damaged roads are closed to everyone but residents and businesses working in the area, according to the county.

For more information, visit bouldercounty.org and click on the "Boulder County Transportation" link under the news tab.

Contact Camera Staff Writer Joe Rubino at 303-473-1328, rubinoj@dailycamera.com or twitter.com/JoeCarmenRubino.