Zebra mussels have infested two more Central Texas waterways: Lake LBJ, upstream from Austin on the Colorado River, and the land-locked Lake Pflugerville, the Texas Parks and Wildlife Department said.

The list of Texas lakes infested with zebra mussels, which are known to clog pipes, water intake systems and cling to boats and docks, has grown to 17 with the addition of lakes LBJ, Pflugerville and lakes McQueeney and Placid in Guadalupe County, parks officials said.

Zebra mussels were confirmed to have infested Lake LBJ, about 40 miles northwest of Austin, after about a dozen juvenile and adult zebra mussels were found July 29 near the Thomas C. Ferguson Power Plant in the Horseshoe Bay area, parks officials said.

Lower Colorado River Authority and Texas Parks and Wildlife biologists also found the creatures attached to structures near Wirtz Dam, McNair Park and Kingsland Community Park. The zebra mussels are expected to spread into Lake Marble Falls, which is downstream of Lake LBJ, parks officials said.

READ MORE: Zebra mussels spotted in Lady Bird Lake; Lake Austin now ‘infested’

Zebra mussels were confirmed to be in Lake Pflugerville, a reservoir northeast of Austin, after Inland Fisheries staff found adult zebra mussels attached to vegetation in the water during a survey.

“It is disheartening to see zebra mussels spreading higher up the chain of the Highland Lakes in the Colorado River basin, as only boats can move this invasive species upstream to uninvaded reservoirs and downstream dispersal is inevitable,” said Monica McGarrity, TPWD senior scientist for Aquatic Invasive Species Management.

Zebra mussels are able to travel from lake to lake because they can survive for days in residual water and adult zebra mussels can survive out of water, parks officials said. Personal watercraft, sailboats, kayaks, canoes and other boats are all required to be drained of water and dried before arriving and leaving a body of fresh water to help avoid the spread of zebra mussels, parks officials said.

The mussels can harm animals in the water and cover rocks, beaches and hard surfaces. They have sharp shells and can clog or attach to surfaces like water intake pipes or boats.

Clusters of the mussels were found clinging to filtering screens in Austin’s water utility intake pipes on Lake Travis in 2018. Divers made the discovery last September while inspecting the screens at the Handcox Water Treatment Plant. The mussels also have been spotted in Lake Austin and Lady Bird Lake.

In February, zebra mussels were found to be the culprit behind smelly tap water in Austin. Their remains ended up in a raw water pipeline at the Ullrich Water Treatment Plant, Austin Water officials said. It was likely some of them died during pipe construction and, as they decayed, released compounds into the water.

But then in May, the mussels spread to Walter E. Long Lake in East Austin and Granger Lake in northeastern Williamson County.

“There is currently no effective way to selectively control or eliminate zebra mussels once they get established in a public lake,” said Mukhtar Farooqi, Inland Fisheries biologist. “This highlights the importance of clean, drain, dry as our best line of defense for reducing the spread of zebra mussels into new lakes.”