May 04, 2015

Shared Sediments

Posing tough questions about how to regulate & control sediment

If “the history of the land is written in the water,” how should we honor, interpret, apply and “beneficially reuse” that history? When it comes to sediments, the answer is “very carefully” (and much more, of course).

Like the hydrologic cycle, the “particle cycle” defines and shapes our watershed experience. We do not always see or feel the daily parade of particles, but we know dirt, debris and other forms of biological and chemical pollution run off rural, urban and suburban lands; flow from facilities; fall from the sky; and otherwise seep from our good green and brown earth into waters large and small. Legacy sediments accumulate over time to create massive, seemingly insurmountable cleanup challenges. Federal, state and local laws, codes and institutional controls, coupled with nongovernmental policies and practices, all fit into the mix of technical, social and economic solutions. To state the obvious, context matters a whole lot, particularly when regulators and stakeholders are attempting to answer site-specific questions such as: To dredge or not to dredge? How clean is clean? How costly is costly? How far back in time and how far upstream should one go to find accountability?

Context Clues

We all know land use determines water use and that an ounce of prevention is worth a pound of cure (and a gallon of clean). It is not so easy, though, for local land use authorities and decisionmakers to align themselves with water goals, standards and effluent limitations. Different constituencies, decision-makers and tools make for complex situations and high-stakes choices.

The difficulty is evident as federal Clean Water Act Section 305(b) reports on state conditions continue to list excess nutrients and sediments as top stressors and total maximum daily loads (TMDLs) continue to identify 15,000 or more impaired water segments due to nutrients and sediments. The National Academy of Sciences 2008 report on urban storm water management also identified “urban stream syndrome”—polluted and high-volume runoff in heavily paved areas leading to stream bank erosion, sedimentation, degraded water quality and diminished aquatic habitat—as a growing problem in need of strategic and innovative solutions.

Many of the most complex and costly Superfund sites across the nation are water bodies with contaminated sediments, from the Great Lakes to Puget Sound, the Duwamish River in Seattle to Newtown Creek’s Gowanus Canal in Brooklyn, N.Y. Important legal and policy debates spring up daily over cleanup, liability and future zoning decisions.

Ports and harbors also are subject to the challenges of sediment, whether or not Superfund authorities, confined disposal facilities and toxic hotspot designations are at issue. Maintenance and construction dredging and dredged material management and disposal decisions loom large in determining the economic viability and public support of ports. Every responsible port and harbor commission should have a plan and professional team focused on sediments and dredged materials (formerly known as spoils) to reduce the risk of spoiling economic and environmental projects.

Regulating Dams

Dams are major players in sediment issues as well. They manage not just the flow of water but sediments, too. Like silt fences and absorbent storm water collars around the borders of construction sites, dams can provide important water quality benefits to downstream ecosystems and communities by stemming and pacing the flow of oxygen-demanding substances. But as we are seeing, over and over, in some areas, dams can contribute significantly to environmental problems, creating sediment sinks as well as conduits for potentially catastrophic releases of all the history behind the dam.

One of the most important players in the drama of restoring and protecting America’s largest estuary, Chesapeake Bay, is the Conowingo Dam on the Susquehanna River in Pennsylvania. One of the big issues is whether the reservoir should be dredged and cleaned, or more attention should be placed on upstream work in Pennsylvania watersheds to increase the success of attaining the Chesapeake Bay TMDL. The U.S. Army Corps of Engineers’ Lower Susquehanna River Watershed Assessment, released in late 2014, done in coordination with the Maryland Department of the Environment (MDE) and Department of Natural Resources, attempts to answer questions surrounding “dynamic equilibrium” of suspended sediments behind the dam and flowing through the dam, particularly after extreme weather and scouring of the reservoir’s bottom. It weighs in on the topics of whether the sediments themselves or the nutrients associated with the sediments present a bigger problem and whether the reservoir behind the dam or the larger watershed above the dam is more important.

The science, finance and fairness of options prompt strong feelings and serious debate. It is playing out in the context of the dam owner’s attempt to renew its Federal Energy Regulatory Commission hydropower license and MDE’s associated water quality certification under Section 401 of the Clean Water Act. More challenges will follow. Divvying up responsibility and sorting out the messy mechanics of collaboration takes time, money and diplomacy, particularly when multiple sovereignties are in the mix. The science and art of interstate collaboration on sediments continue to evolve.

I am not sure who the original source is for the quote about land history being written in the water. It is different from history being written “on” the water’s surface, where it quickly fades or dissolves into oblivion. No, sediments and other daily matters can stick around for a long time, and the water body will remember it. It is all a reminder that watersheds are like libraries—important repositories for learning from known and unknown authors— and that an Aldo Leopold “land ethic” offers hope for waterways, basins and future reservoirs of goodwill.

My sediments, exactly.

About the author

Benjamin H. Grumbles is acting secretary, Maryland Department of the Environment. Views expressed in this column may not necessarily reflect those of the Maryland Department of the Environment. Grumbles can be reached at [email protected].

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