In connection with the Town-Wide Read program focussing on wildlife and conservation,  Beth Lambert, River Restoration Scientist in the Division of Ecological Restoration, an agency under the auspices of the Mass Department of Fish and Game, spoke at the Haston Library this evening on the subject of “rewilding” rivers in Massachusetts.

Although newly established, the Division has already completed 17 river restoration projects and is currently working on around 75 more. The Division’s goal is simple: revitalize rivers and wetlands and make them healthy again. Healthy rivers are connecting corridors which transport water, sediment, nutrients, and organic material; they serve to sustain populations of fish and wildlife; and they maintain water quality for human communities as well.

Before European settlement in the 17th century, Native Americans used the rivers in New England extensively, particularly for fishing and transportation; however, river flow was not blocked. When colonial towns were established, they all soon had mills, for both grinding flour and cutting timber. As towns developed into cities over the next century, New England became the center of the Industrial Revolution, and the local economies became regional. Rivers were dammed to provide power for the burgeoning textile mills, among other industrial uses. Dams were controversial from the beginning, Ms Lambert emphasized, and gave a short history of the Billerica Dam in Concord as an example. Built in 1710, the first lawsuit about it was filed in 1711. In 1722, the dam was removed, rebuilt, torn down, and rebuilt again. In 1723, an agreement was reached whereby water would flow freely for 2 months out of the year. Another lawsuit was filed in 1798, but in 1828, the dam was built up even higher. Yet another lawsuit was filed in 1860, and today, in 2011, discussions regarding the dam’s fate are ongoing.

Startling as these numbers may seem, there are more than 3000 dams in Massachusetts, of which only 43 serve for flood control, 44 are licensed for hydropower generation, and 164 regulate water supplies. That leaves an awful lot of dams which would be eligible for removal.

So what is the problem with dams and why would you want to remove them? Dams basically block stream flow. One consequence is that ponded water heats up and pours over the top of the dam; cold-water fish such as trout cannot tolerate these warmer water temperatures. Behind dams, sediment builds up and aquatic plants flourish, thus depleting biological dissolved oxygen and negatively impacting the environment for native fish. The dammed streams, with their lowered oxygen levels, higher temperatures, and high nutrient accumulation, also become sinks for toxic chemicals. In contrast to the popular view, most dams do not even control flooding.

In 2005, the state legislature passed a series of laws which upgraded standards for dam safety, which may have caused dam owners to think hard about removal, in that they would now be responsible for both maintenance and safety inspections, and would have legal liabilities for any damages caused by poorly maintained structures. (In Massachusetts, about a third of dams are owned by a municipality, a third are privately-owned, and a third are state or federally-owned.) As communities become more aware of the science behind river restoration and the need for it, they are seeking funding which will help pay for dam removal, some of which is available through state and federal sources.

Dam removal is not easy: sediment testing and engineering studies must be undertaken, and cultural and historical factors must be considered. The process is rigorous, with public conversation and dialogue a necessity. Fortunately, a number of projects have been quite successful. I enjoyed seeing the “before” and “after” photos for projects on the Housic River, the Eel River, Plymouth Town Brook, Yokum Brook, the Jones River, and others. One of the bigger projects now in the works is the State Hospital Dam on the Mill River in Taunton, which is slated for the summer of 2012.

At the end of her talk, Ms Lambert opened the floor to questions. We asked about projects in our area, about the Connecticut River, about beavers (the original dam builders!)  and plant re-seeding, and about her department’s annual budget, which is $250,000 for a director and two staff. I think it’s money well-spent.