Onondaga Lake's biggest pipe comes up for permit renewal

The discharge permit for the Metropolitan Syracuse wastewater treatment plant, the single largest pipe into Onondaga Lake, is up for renewal and modification, and the state is taking public comment on the draft through October 2.¹

The plant sits at 650 Hiawatha Boulevard West on the lake's south shore and treats the sewage of Syracuse and most of the county. On September 2 the DEC published a draft permit and a tentative decision to approve Onondaga County's application, with a finding that the changes will have no significant environmental impact.¹ That decision is provisional until the comment window closes.

Onondaga Lake's recent history runs through this plant. In the 1990s the treated effluent carried about 90 percent of the ammonia and somewhere between 40 and 60 percent of the phosphorus entering the lake from outside, on roughly a fifth of the water. Ammonia is toxic to fish and the phosphorus fed the algae that stripped the deep water of oxygen every summer. Fewer than ten fish species were holding on in the lake. The county then rebuilt the plant: a biological filter that converts ammonia to nitrate came online in 2004 and a high-rate settling stage for phosphorus followed in 2005.² Ammonia loading from the plant fell 98 percent and phosphorus loading fell 86 percent. In 2008 the state took the lake off its impaired-waters list for ammonia, and DEC biologists now count about 60 fish species using it.³ Walleye, yellow perch, freshwater drum, longnose gar and channel catfish have all been recorded in the lake over the past two years, and a common logperch, a small bottom-hugging darter, turned up there today.⁴ The introduced round goby and European carp are in the same records.⁴

The lake is not clean. Both the north and south basins remain on the state's impaired-waters list for other pollutants, each under a pollution budget, and the lake bottom is a federal Superfund site listed in 1994 for industrial contamination that predates any sewage upgrade.^5, 6 What the plant controls is the part of the problem that has actually been turned around, which is why the terms of its permit matter more here than they would on most lakes.

They matter a little more this month. The plant normally sends about 130 cubic feet per second of treated water into the lake, roughly 20 percent of everything that flows in over a year. Onondaga Creek at the Spencer Street gauge, just before it reaches the lake, is running at 52.9 cubic feet per second.⁷ The plant is currently putting in about two and a half times as much water as the creek. Two weeks ago the creek's collapse upstream at Dorwin Avenue was the subject here; since then the abnormally dry area of Onondaga County has grown from 85 percent to essentially the whole county, and the natural inflow to the lake has kept shrinking while the plant's contribution holds steady.⁸ In a dry fall the lake's chemistry is more a function of what comes out of that pipe than in a wet one.

The plant is not on EPA's current list of facilities in significant noncompliance. The published notice does not spell out what the modification changes, and that is the first thing anyone reading the draft should look for: whether the effluent limits for ammonia and phosphorus stay where they are, tighten, or loosen, and what the permit requires when heavy rain pushes the plant toward its wet-weather capacity of about 371 cubic feet per second.

Comments go to Trendon Choe at DEC Region 7 in Syracuse (dep.r7@dec.ny.gov, 315-426-7438) through October 2.