You have a retention pond. It’s got a few small patches of cattails around the edge. From an appearance standpoint you don’t mind the look, and animals seem to like them. Should you have them in your ponds? The answers, like many questions about pond management (and anything else), depend on who you ask. There are the People Against Cattails (PAC) and the People For Cattails (PFC). Side note: I just made up those acronyms and for fun, I’m going to try to start using these in regular conversation.
The following story is an extreme example of the confusion regarding whether cattails should be in ponds. We had a stormwater pond owner who had paid a contractor to install cattails at initial construction; these plants were specified on the design plans. A municipal inspector came back a year later and told him to remove these invasive plants! A year after this, he was told by a different inspector with the town to put them back in, as they were on the plans.. The town has since gone to a third party inspection system, and has a strict rule on cattails: No cattails in ponds! The good news is that these types of situations are less common than 3-4 years ago. In most cases, municipalities are clarifying their stances on retention pond requirements.
When assessing ponds we take several factors into consideration when developing a cattail management strategy:
1. What municipality are you located in? Some cities and towns will encourage you to have cattails while others will tell you to remove and control them. The decision to have them in your pond, often is not a decision at all, you always want to comply with local requirements. Not being familiar with local requirements (and documenting all communications with inspectors) will cost you money down the line. City of Durham, Town of Cary, City of Raleigh all have slightly different takes on cattails, and experienced professional can advise on pond management strategies.
2. What type of stormwater system do you have? Wetlands, bio-retention systems, and retention ponds are different types of stormwater systems.
- Wetlands: If you have a constructed wetland with a variety of attractive plants, leaving cattails uncontrolled can result in eventually having a pond with ONLY cattails. Cattails are aggressive, and can dominate these types of systems. For situations such as these, we often incorporate a maintenance plans that includes regular control of cattails. This allows for more diversity of attractive wetland plants. (See picture below of a constructed wetland with no cattails.
- Bioretention systems: Cattails in a bioretention system often indicates standing water, and poor drainage. Complete removal is often desired in these cases, but you may be facing a bigger problem with your bioretention system.
- Retention ponds:If the pond is deep enough, cattails will not be able to grow, and they may not pose a problem. If the pond is shallow, and cattails start causing blockages at drains, you should strongly consider a control strategy.
3. Other considerations: Mosquitoes. This hot button issue deserves a full blog post of its own (and will be addressed in the next blog). The People Against Cattails (PAC) often claim that cattails contribute to mosquitoes. There are several studies that claim that cattails are good habitat for mosquitoes, especially floating cattail mats: here is a good read from the NCSU Stormwater Engineering Department: http://www.bae.ncsu.edu/stormwater/PublicationFiles/Mosquitoes2005.pdf
In summary, are cattails unwanted? Well, it depends on several factors including to which side you belong (PAC vs PFC). Be sure to keep us in mind if you want some guidance how you can manage your pond. Let me know if you have any stories or comments regarding cattails.