Flood watch canceled after potential dam breach averted

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RENO, Nev. (KOLO) - The National Weather Service says a flood watch has been canceled for the Steamboat Creek and Pleasant Valley areas. That announcement came late Tuesday morning.

NWS says mitigation efforts have reduced the hazard of a potential breach of the dam at Little Washoe Lake. That's after Washoe County said any threat had significantly decreased, slowing seepage and downgrading the situation from "imminent threat" to "watch."

State Engineer Jason King says crews worked to fortify the dam to prevent major damage, and significant progress has been made in that direction. A more permanent fix is in the works.

A state dam official says the dam was due for inspection next week, and if not fortified when it was, it could have broken any time.

If the Washoe Lake Dam had breached, according to Washoe County, the Steamboat Creek areas would be subject to low-level flooding. Residents in those and surrounding areas were asked to prepare to evacuate if notified.

Sandbags are available at the following locations as a precaution:

• Washoe County Operations Yard, 3101 Longley Lane, Reno
• Highland Ranch Parkway, one mile west of Pyramid Hwy, Sparks
• Truckee Meadows Fire Protection District Station #30 at 3905 Old Hwy 395, Washoe Valley
• Gander Lane and Eastlake Blvd. in Washoe Valley
• Paddlewheel and Andrew Lanes in Pleasant Valley
• Toll Road and Geiger Grade
• Truckee Meadows Fire Lemmon Valley Volunteer Station #223 at 130 Nectar Street
• Arizona and Lemmon Drive in Lemmon Valley
• Blue Heron/ Warrior Lane in Belli Ranch Area
• TMFPD Hidden Valley Fire Station
• Red Rock Volunteer Fire Station

If the dam had broken, about 950 acre feet of water in Little Washoe would have drained; Big Washoe would also experience draining. Water would drain from Little Washoe into Steamboat Ditch north into the Pleasant Valley area, leading to flooding. It would also potentially cause another smaller dam, Pagni Dam, to breach. See the attached pdf for a map of what could be affected. The area is roughly the same as what was affected during flooding in January 2017, and anyone affected by that incident could be similarly affected this time if the dam were to breach.

The dam is near the entrance to Old Washoe City along Old 395 (395 Alternate). It dates to 1863 and the damage is from wear. A fisherman seeing a whirlpool at the dam reported it, leading to a fresh inspection by state officials and a finding that a breach could be "imminent" if fortification were not done quickly. An inspection in fall 2017 didn't reveal any significant problems.

Nevada State Engineer Jason King released this statement early in the afternoon: "The Nevada State Engineer is actively managing a partial failing of the Washoe Lake Dam in Washoe Valley, in accordance with the Dam’s Emergency Action Plan procedures. Currently, the dam is not breached and repairs are underway. The State Engineer is working closely with other state and local officials to restore the integrity of the dam and protect the public. If an evacuation becomes necessary, Washoe County safety officials will notify impacted residents. For updates on evacuations or other public safety announcements, go to washoecounty.us/."