Over the past couple of years, the Neponset River Watershed Association has been partnering with the Milton Department of Public Works (DPW) to improve water quality along Milton's Pine Tree Brook. The Pine Tree Brook Neighborhood Association (PTBNA) has been a strong supporting force for this project, mobilizing community members to participate in a variety of related activities.

The stretch of Pine Tree Brook that's being improved extends between Blue Hills Parkway and Thacher Street. Several bioretention cells have been built here to catch and filter runoff (also called "surface water") from adjacent streets. Originally, this street runoff was piped directly into the brook from catchbasins (grates on the streets). This process caused the brook to deteriorate.

Now, water from the underground pipes has been diverted into the bioretention cells to be filtered, cooled-down, and slowed-down before it enters Pine Tree Brook. Bioretention cells are considered a progressive tool for cleaning-up water. Learn more about bioretention cells.

What the deal is with street runoff

Contaminants from daily life pollute street runoff. For example, runoff contains products from the burning of fuel, fertilizers and herbicides from lawns, ice-melting materials from sidewalks, sand, and seepage from people's garbage cans. Street runoff is also thermally polluted; it's been warmed-up by its travels over dark-colored driveways, streets and roofs. Also, water that's run over streets, sidewalks, grass ("turf"), and then through pipes - travels quickly. See how each of these characteristics of runoff affects a brook, below.

If a brook's pollution levels get high enough, certain aquatic species can completely die out. As one species vanishes, others follow; they are all inter-related in the food web. Ultimately, the natural system of the brook becomes increasingly deteriorated.

Fast-moving water entered a brook over the ground or through a pipe can erode the stream's banks. In turn, this clouds the water, clogs the gills of stream-bottom insects, makes it harder for aquatic wildlife to move around, feed or interact with one another, and damages the eggs of fish and aquatic insects. Every component of an aquatic system is important to the health of a stream. So, when one species is hurt by poor water quality, so are the other species - and the stream, as whole.

Warmed water has less oxygen than usual. This can stress - and eventually kill - aquatic wildlife. Dissolved oxygen is important for breathing -

Learn more about stream and river ecology.

Now that you understand why the filtering action of bioretention cells is so beneficial for streams, let's get back to what NepRWA and its project partners are currently doing along Pine Tree Brook.

Most recently, NepRWA, the DPW and PTBNA have been working together to beautify one of the streamside bioretention cells. On Monday, September 11, 2006, a crew of employees from the DPW and NepRWA, members of PTBNA, and other Milton residents planted a bioretention cell with Joe-Pye weed, Arkansas bluestar, Steeplebush, Feather reed grass, New England aster, Blue flag iris and Coreopsis. These plants are showy, hardy species, and many are native to New England. They should be able to tolerate the extreme growing conditions of the bioretention cell - periods of saturated soils and standing water, extended periods of dryness, pollutants from street runoff, etc. See plant pictures above and below.

Come spring 2007, the rest of the bioretention cells will be planted. In addition to the plantings, stormdrain markers and other signage will be posted in the vicinity of the brook to help neighbors keep local water clean.

If you walked by the bioretention cells this past summer, you may have noticed that the bioretention cells were filled with an assortment of wildflowers. Some of these plants had sprouted from seed mixtures spread during the last growing season and some were a result of seeds already in the soil or carried by the wind or small wildlife. Present plants include Jewelweed, Milkweed, Boneset, Indian blanket, Black-eyed Susans, Smartweed, Pokeweed, Burdock, Common evening-primrose, Chicory, Coreopsis, Yellow wood sorrel, Japanese knotweed, Purple loosestrife, and thistle, among others.

To learn more about this project, contact Carly Rocklen at rocklen@neponset.org or 781-575-0354. Contact Dick Russell at 617-696-3751 to find out more about the Pine Tree Brook Neighborhood Association.

Pictures of bioretention cell plants: