DEP directive to have dams handle 10 times more water needs assessed
The City of Lock Haven has some important and challenging decisions to make about public water.
No, not about water quality, but water safety.
The state Department of Environmental Protection says the city must address aging dams at its three reservoirs because the dams no longer meet flood requirements.
It is coincidence that the directive comes soon after the severe problems seen at Lake Oroville in California, where 188,000 people were evacuated because an emergency spillway was damaged due to prolonged, heavy rain.
Regardless, the public must know the dam in Castanea, at a reservoir no longer part of the public water system, was built in 1927; the dam at Keller Reservoir above McElhattan, the primary intake reservoir, was reconstructed in 1956, and the dam at Ohl reservoir in Sugar Valley, which is the reserve collection and storage reservoir, was built in 1964.
The Keller dam has not had any significant public investment in 40 years.
Consultants say none of them can safely deal with DEP’s “probable maximum flood” or PMF, City Manager Richard W. Marcinkevage told council this week.
A PMF would involve “significantly greater volumes of water than these dams were designed to handle,” he said.
The dams would not be able to store or safely pass the resulting water flow.
The flow during the Agnes Flood of 1972 was 1,000 cubic feet per second, but the flows that DEP now requires the dams to deal with are more than 10 times that number.
The cost of updating the dams could range from $12 million to $15 million, according to studies by two firms the city hired to look into the matter: Gwin, Dobson and Foreman Inc. and Applied Weather Associates.
One suggestion is to breach the Castanea dam as it’s not in use.
To also assess the situation, you need to understand that if the upstream Ohl dam would be breached, so would the downstream Keller impoundment.
Our area has seen its share of flooding over the years.
In the more modern era, the Agnes flooding in 1972, the snow melt and heavy rain flood of 1996, and major flooding in 2004 and 2011 come to mind.
With changes in the watershed and the increased frequency of severe storms, investment in reservoirs and dams must keep up.
We do wonder if the 10-times more water-flow formula the DEP is using is perhaps over amplified.
We do understand from the city manager that, besides addressing higher flood flows, the proposal include costs to replace piping and valves in the dams that are original to their construction.
No one likes paying higher rates, for example, when the city had to comprehensively update its sanitary sewage treatment system a few years ago to improve acceptable discharge limits.
What the city did then, we hope they can do for the dams … that is, to obtain significant grant funds from the state of Pennsylvania to help finance the cost. A grant application to Pennvest — the Pennsylvania Infrastructure Investment Authority — will be so very important and should help be the basis for any formal decision on whether and when to move forward.
We urge water customers, taxpayers and the public to learn more about this, and weigh in with city government.