Left: A view north toward Smith Point. Note trees in water. Middle: Southern shore of Smith Point, and Heron Rock. Bottom: View looking east from the center of Smith Point.

These photos of Smith Point were taken on March 8, 2011, a day after the winter’s snow finally melted. The massive melt, hastened by a day of rain, left the pond spilling over its banks in many places. A quarter of Smith Point was under water.

With the water so alarmingly high, and last year’s floods still fresh in memory, the sluggish flow of Chester Brook, the discharge channel for Hardy Pond, has become a matter of renewed concern. For years, the channel has been filling with sediment, but the two 100-year floods of March 2010 appear to have brought the flow almost to a full stop.

There has been discussion among City officials about cleaning out the channel, and an outside engineering study has recently recommended doing so. Of course, a project like this cannot be accomplished overnight. Riparian rights must be determined, plans drawn up, Conservation Commission approval obtained, funding found, and bids let before actual work can begin. The question is, can a sense of urgency be invoked?

Since last year’s major floods, the water level of Hardy Pond has been on average higher, the pond has spilled over its banks more often, and high water has receded more slowly — all directly tied to silting of the brook. The situation could lead to ever more destructive flooding if we’re hit by another extreme weather event, a possibility we can’t rule out in this era of climate change.

In addition to clearing of the outlet channel, the outside study outlined other steps to reduce flooding risk in the large Hardy Pond watershed. In an ideal world, they’d all be given priority as a matter of public safety, and completed without delay — so pond abutters and area residents could feel secure in their homes once again. That can happen only if the mayor and city council are aware of the issue and fully understand it. Getting that message across is our responsibility, all of us who care about Hardy Pond.

It is instructive to read what the study’s authors say about Chester Brook, revealing how relatively little it would take to remedy the situation:

We observed that Hardy Pond discharges to Chester Brook in the northeast corner of the pond which extends easterly adjacent to the Stearns Hill Road development and heads southerly along Lexington Street and ultimately flows toward the Charles River. The easterly portion of Chester Brook was observed to have standing water with little to no flow. We encountered a concrete control structure ( a rectangular weir) at the outfall from the pond to the Brook (see photo 2). Compared to known outlet elevations and water surface elevation at the time of the site visit we estimated that the weir elevation is set at an approximate elevation of 194.5′. We observed that the water surface elevation was approximately 13″ above the control elevation which indicates to us that there are likely other conditions downstream that are controlling the current water surface elevation.

Our site walks identified that Chester Brook shows some signs of side bank erosion and sedimentation (see photo 4) in the channel that is reducing the available cross section for conveyance in low flow conditions. We also observed two areas where large stones have been placed across the channel to create walkway paths. A worn path leads to and from each crossing, indicating these paths are frequently utilized by pedestrians. These crossings have effectively created a damming effect and are restricting flow (see photo 5).

We recommend removal of sedimentation accumulation and obstructions within Chester Brook and restoration of the full channel cross section. This maintenance task was also recommended in the Chester Brook Master Plan (Rizzo, 2002).

This action would likely require additional permits for work affecting wetlands, and within stream banks. We would recommend having a pre-application meeting with the Army Corps of Engineers, DEP and the Waltham Conservation Commission before fully pursuing this option. We would expect costs for this work would be around $280,000 and require cooperation from adjacent property owners. Ideal locations to access the Brook would require permission to access private properties such as Windsor Village development, or Papa Gino’s parking lot.

Coler & Colantonio, Inc.   DRAFT Hardy Pond Drainage Area Study, Waltham MA, October–November 2010 Excerpted from Pages 5, 6 & 14

See related posts: High Water II*, High Water III, Dead Fish, and Mono Lake*. See also permanent page: The Great Flood. Click an image to enlarge it, and browser’s back arrow to close. Comments are welcome.

 

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