POINT INTERCEPT SURVEY
In 2021, Cross Lake/Snake River Association contracted Limnopro to conduct an aquatic plant survey.
The survey was conducted both in the late spring, during peak growth of curly-leaf and later in the summer to determine the specific plant community in the lake, after the curly-leaf pondweed dies off.
What is a Point Intercept Survey?
Point-intercept surveys provide an assessment of the entire aquatic plant community in a lake. They are repeatable and great for evaluating management progress and lakewide changes in the plant community over multiple years. For those lakes with intensive management, annual point-intercept surveys may be appropriate.
What did the survey find?
It found that the plant community in Cross Lake consists of 29 species of plants or macroalgae.
- Species richness within the lake was high, but most of the beneficial species found were rare. Beneficial aquatic plants will discourage the growth of undesirable plants and algae, provide food for fish, filter the water and wildlife, and help stabilize both the shoreline and lake bottom.
- The most common native plants found were water celery, waterlilies, coontail, small pondweed, and filamentous algae. We want the common native plants. They are the plants that make the lake healthy.
- A total of twenty three (23) acres of curly-leaf was found, which is 5% of the 507 acre littoral zone.
- Sixteen (16) acres of Eurasian watermilfoil, another AIS known to infest the lake, was found. Approximately six (6) acres of the Eurasian watermilfoil overlapped during part of the year with curly-leaf pondweed.
What does it mean to me?
The overall survey concluded that the plant coverage in the lake was low, which was likely a result of the poor water clarity.
What does poor water clarity affect?
- Poor water clarity can affect plant, insect and fish communities and reduce recreational opportunities.
What can we do about it?
The Cross Lake/Snake River Association Water Quality Team is evaluating each of recommendations provide below by Limnopro; consulting with governing agencies such as Pine County Water & Soil and the MN DNR to determine our action plan. As well as identifying the necessary funding. {As of Jan 2022}
We will communicate our response plan as soon as it is finalized.
Management Recommendations (Limnopro Survey - Page 12)
- CLP chemical herbicide treatment if it persists in areas that it impedes with recreation.
- EWM chemical herbicide treatment at maximum labeled rate of 2,4-D as budget allows.
- Enrollment to lake water quality monitoring program to collect total phosphorus, chlorophyll a, and Secchi depth readings once per month during open water season.
- Develop a lake diagnostic and management plan to summarize existing data and information on the lake and determine gaps of knowledge that can help toward increasing plant coverage.
- Carp survey using trap nets, seine nets, or electrofishing to determine carp biomass.
- Nutrient budget to quantify sources and sinks of phosphorus to the lake for identifying management opportunities for reducing nutrients.
- AIS Early Detection Survey at the public boat launch during late summer to look for first indication of Eurasian watermilfoil, starry stonewort, and other AIS.
- Annual hydroacoustic survey for monitoring of biovolume, canopy depth, and coverage.
