Wednesday, August 31, 2011

Stormwater pond maintenance & muskrats - are they friend or foe?

This is a stormwater treatment facility, also known as a stormwater pond, near the center of the Burlington Hill Business Park, in Burlington Washington. Surrounding the pond are approximately 25 businesses, including a farming supply store, a wood molding and truss manufacturing mill, a UPS transportation facility, a site development company with lots of earth moving equipment, a soil and stone stockpiling business, landscaping supplies, a coffee roaster, several auto dealerships, assorted warehouses, and others. Stormwater from all the roofs, sidewalks, outdoor storage areas, car dealer lots, stockpiles, outdoor processes, and all areas from the entire business park drain here, or into another pond just like it. When the water level reaches the pond outlet, it drains through a pipe to Joe Leary Slough, a polluted fresh water stream that meanders west, into Padilla Bay, in Puget Sound.

Stormwater ponds are common features in our developing, increasingly impermeable landscape - they provide a place for water storage, and more specifically, stormwater storage. They also provide a limited amount of pollutant removal, and sometimes, they’re even pretty. Depending upon the land use activities surrounding these ponds, they have the potential to fill up with sediment and vegetation, and in this case, cattails. While cattails are fantastic for helping to clean up polluted stormwater, they are highly invasive, and often completely overtake stormwater ponds, to such an extent that water storage ability is compromised.

To make a long story short, stormwater ponds require maintenance, most typically, sediment and vegetation needs to be removed every few years, and more frequently if the pond gets filled up. This pond filled up with cattails, so the coffee roaster, farm supply manager, earth mover, and a few others had a meeting after the City of Burlington told them they had to “clean out” the pond. The City told them exactly what needed to happen, and then the business owners collected money amongst themselves, and hired the earth mover to remove some of the cattails. Enter Eben Twaddle, earth mover, and heavy equipment genius, whose businesses is located next to the pond.

Eben and I are an unlikely pair. I’m obsessed with preventing water pollution, and Eben loves to develop land with heavy machinery. I like fluvial geomorphology and riverine processes, and Eben is equally enthusiastic about landscape processes that are accomplished with his fleet of machinery. That’s his giant track hoe in this picture, scraping up cattails, and piling them up for removal. Eben and I had a long talk at the pond, and I was amazed at what we had in common. And then he told me his idea. He wants muskrats to live in the pond, because muskrats eat cattail roots, lots of them. I was speechless – it was a terrific idea.

I went home, and stayed up past my bedtime reading about muskrats. One of the first articles said that muskrats are large aggressive rodents that carry disease, mites, and ticks. I kept reading. Muskrats, which are native to North America, eat a variety of aquatic plants, but their favorite food is cattail roots. Muskrats burrow into banks or berms, and sometimes build lodges and platforms to nest and rest on. This stormwater pond doesn’t have berms; it’s a more traditional pond which was excavated out (by Eben) so burrowing won't cause leaking. Muskrats make a valuable contribution to aquatic ecosystems because they favor cattails. As cattails disappear, habitat is opened up allowing for a diverse plant community, and along come more diverse animals, such as ducks, geese, shorebirds, snakes, turtles, frogs, and maybe predators, including coyotes, and large raptors!

Eben might be my new best friend. Introducing muskrats to the pond may save money, decrease the amount of maintenance that needs to be done, maintain its stormwater functions, and increase the pond’s wetland habitat value. There could be some complications, such as clogged outlets, and a proliferation of muskrats – but these can be addressed. There’s a good chance his idea will work, and it’s the best idea I’ve heard in years. I think it’s worth a try, don’t you? Thanks for reading.


  1. This place is a big mess! The flood badly damaged the area, leaving behind piles of branches and unkempt grass. Good thing he thought of having muskrats to eat the cattail roots. It gave them a shelter while they give you a clean pond that can help prevent flooding.

    >Richelle Loughney

  2. Always keep grass clippings and leaves out of ponds. Make use of phosphorous-free fertilizers for the soil, but remember to only apply the needed quantity of fertilizer. Also, have your soil tested to determine how much and what type of fertilizer to use since what the soil does not absorb will be washed into storm sewers.

    Monica Barnes