Invasive Plant and Animal Species

Native aquatic plants and animals are beneficial to the health of Sunset Lake. Native species provide valuable functions such as filtration and nutrient attenuation and help to combat negative influences of the surrounding urban development on water quality. The amount of native plants in the lake increases and decreases naturally over the years due to environmental conditions. However, human impacts on the lake can also increase the amount of native plants; visit our Water Quality Testing page for more information. In years where there is an increase in plant growth, we must be careful not to do more harm than good; removal of plants by raking or similar means can spread plant seeds resulting in an increase of plants rather than a reduction. If you have a concern about the plant growth, contact your district delegate or info@slahampstead.org. For more information about the native plants in Sunset Lake, see the information about the 2009, 2012, and 2021 plant surveys at the bottom of this page.

Invasive plant and animal species are detrimental to the health of the lake. They can crowd out native plants and animals and affect people by fouling boating, swimming, and fishing areas, and reduce shoreline property values.

There are two invasive plant species on the shoreline of Sunset Lake: Purple Loosestrife and Common Reed (Phragmites australis). Purple Loosestrife was originally found in a 2012 vegetation survey that is available at the bottom of this page and is still present on Sunset Lake shores. Management actions for Purple Loosestrife were last taken in 2021 and 2022 as documented in this blog post. Common Reed was discovered in the 2021 vegetation survey that is available at the bottom of this page and discussed in this blog post. We started to mitigate the Common Reed in the summer of 2022 as discussed in this blog post. Thankfully, both of these invasive plants are "emergent" or shoreline species which are not as detrimental to the health of the lake as submerged or floating species. However, they should still be mitigated to prevent spread and negative impact on the native plants and wildlife in the area. 

Asian Clams, an invasive animal species that is spreading in the local area, are the only know invasive animal species in Sunset Lake and were discovered in 2014. They likely still exist in Sunset Lake today as there is no good management technique to eliminate them.

Invasive Species in Nearby Water Bodies

Most water bodies in New Hampshire have some invasive species, including our closest neighboring water bodies. Fanwort exists in Shop Pond just across Rt. 121 from the lake, Big Island Pond has been combating Fanwort and Variable Milfoil for years and has a new infestation of European/Spiny/Brittle Naiad, and Angle Pond has Purple Loosestrife, Common Reed, and Chinese Snails. See this NH DES exotic species map and spreadsheet for the latest inventory of invasive species across all NH water bodies and the Sunset Lake Invasive Species Guide available for download below for pictures and details about the different NH invasive species and which ones are present in local water bodies.

How We All Can Protect Sunset Lake from Invasive Species

We must be very careful to not introduce other invasive species into Sunset Lake. Not only is it important for the continued health of the lake, but as of January 1, 2017, it is the law that all watercraft, including non-motorized and paddle vessels, must be cleaned, drained, and dried between use in NH lakes. This is especially important since all of the local water bodies around Sunset Lake have invasive species which could easily be transferred to Sunset Lake, even by kayak, canoe, paddleboard, or fisherman gear. Asian Clams most certainly came from another water body into Sunset Lake via some method like larvae on the hull or in the bilge or engine of a boat, from water in a canoe or kayak, or even via a fisherman's bait bucket. This is why the clean, drain, and dry law is so important. For more information about invasive species and clean, drain, and dry procedures watch the video below and visit the clean, drain, & dry page on nhlakes.org and check out their latest brochure.

As an association, we take a proactive approach in monitoring our lake for invasive species. There are individuals who are weed watchers from the surface and below. The link below will let you download our most up to date Sunset Lake Invasive Species Guide. Should you see a plant that matches the description of any listed invasive species, please contact your district delegate or info@slahampstead.org.

Three different aquatic plant surveys have been performed for Sunset Lake and are available below.

The first two surveys were performed when there were flare-ups of aquatic plant growth around the time of the reports. These reports confirmed that the amount of weeds in the lake, even with the flare-ups, were not abnormal and important for the health of the lake. There were no invasive plant species found in the 2009 survey and Purple Loosestrife was the only invasive plant species found in 2012.

In 2021, another plant survey was performed to check the lake for invasive species and to set a new baseline of native vegetation for reference by our volunteer weed watchers in the coming years. For more details about this survey, see this blog post.

For continued health of the lake and plant population, these reports recommend continued water quality monitoring and proper watershed management techniques, which include Healthy Lakeshore Living and Lakeside Landscaping.

How can I help?

We want to thank our members who support the SLA with their membership and contributions. If you would like to help fund future plant surveys and support our efforts to keep Sunset Lake invasive free, please consider joining or contributing at the Weed Watcher or Lake Leader level, which directly funds these efforts, as documented on our Membership page .