Mill Creek is one of Westmoreland County’s natural treasures. Now, it is even better. Growing Greener II funding supported much-needed projects to stabilize the streambank and reduce the amount of sediment entering this exceptional waterway. Mill Creek is an important tributary of Loyalhanna Creek, which supplies drinking water for residents of Ligonier Township and affects water quality in Latrobe, New Alexandria, and communities downstream.
This was the first stream-stabilization effort to be completed under the Growing Greener II County Environmental Initiative, which also included funding for new trails and recreation areas, farmland and open space preservation, and other projects to improve the quality of life in Pennsylvania.
Mill Creek is one of the last remaining high-quality recreational resources in the Ligonier Valley, according to an extensive report prepared in 2004 by the Forbes Trail Chapter of Trout Unlimited. The group’s conservation plan for the watershed identified the creek’s outstanding qualities: its pristine beginnings in Laurel Mountain and the fact that it is a viable fishery for nearly its entire length. Trout Unlimited also noted Mill Creek’s few but significant trouble spots, including the site where Hannas Run enters the stream just below the community of Oak Grove. Here, the report said, bank erosion was perhaps “the most severe of any area in the entire watershed,” and deemed this site the “number-one priority” for remediation.
Before the improvements, the lack of streamside trees and vegetation combined with Mill Creek’s tall banks of soft, loamy soil to make the site extremely vulnerable to erosion, with the loose soil polluting the stream and degrading water quality downstream. This severe erosion contributed to the high volume of sediment that regularly built up where Mill Creek crosses Route 30 just west of Ligonier. This buildup required frequent dredging to prevent flooding.
To solve the problem, the Westmoreland Conservation District, the Forbes Trail Chapter of Trout Unlimited, the Loyalhanna Watershed Association, the Western Pennsylvania Conservancy, the Youth Conservation Corps, the Fish and Boat Commission, Outside In, the Boys Brigade Camp Association, and local landowners joined forces and took a cue from nature.
“A large log had fallen into the stream against the east bank of Mill Creek and was helping to deflect the force of Hannas Run. So we added eight more like it, configuring these nine logs in groups of three, and anchoring them at an angle that would deflect the flow of the water from Hannas Run,” explained Rob Cronauer, watershed specialist for the Westmoreland Conservation District. This is one of the first times this log-deflector approach has been used to improve a stream in Westmoreland County.
The remediation team also added a large mass of tree roots and 100 tons of stone to absorb the force of the water flowing in from Hannas Run, and planted 100 live willow branch cuttings to help stabilize the most vulnerable section of Mill Creek’s streambank. Additionally, the team re-graded the streambank to reduce the severity of its slope.
The work group hopes to put the finishing touches on the job by planting 20 trees to bring even more stability to the streambank. The Westmoreland County Board of Commissioners, in coordination with the Westmoreland Conservation District, identified five other water-quality projects in the county, in Allegheny Township, New Kensington, Mount Pleasant Township, Derry Township, and Donegal Township.
“The projects we identified for funding in Westmoreland County address many of the concerns our residents told us were important to them when we did the county’s comprehensive plan,” said Tom Balya, chairman of the board of commissioners. “These improvements will benefit all of us—our quality of life, our environment, and our economy.”