Q & A WITH HOLLY
Why is there a need for a living machine in the pond(s) at Sweet Springs Nature Preserve? Have any other solutions been considered?
The ponds have become very anaerobic over the years due to the large amount of eucalyptus debris that falls from trees overhead and decomposes in the water. This makes it very difficult for freshwater organisms to survive at all levels of the food chain. Dredging the pond would certainly be another option, but it would be extremely expensive. It would also require pulling out existing fencing to get large equipment in, and would likely cause extensive damage to trails and vegetation. It is also unlikely that we could get permits to do it that way as threatened and endangered animals would be put at risk.
What species of animals inhabit the pond, and why are the turtles significant?
The southwestern pond turtle is the only freshwater turtle found in the State of California. It is currently considered a species of special concern by the CA Dept of Fish & Game. We are seeing little recruitment of young turtles at Sweet Springs. Although we have not done a comprehensive analysis to determine the causes, there are likely many factors at work – predation from native & nonnative species (e.g. raccoons, water fowl, bullfrogs, etc.), insufficient sun/warmth from shading, insufficient food from poor water quality and illegal collecting. We have not done recent wildlife surveys to identify all of the animal species that inhabit the ponds, but historically there are a wide array of bird species and a limited number of frogs, fish and macro invertebrates.
How deep is the pond and how much does the water level fluctuate throughout the year?
We haven’t taken any recent depth measurements and it is filling up with sedimentation. There is one relatively deep channel in the center that is 4-5 feet. Most of the pond is relatively shallow – less than 3 feet. It fluctuates considerably during low and high tides. I think we would probably want to take some new depth measurements before we get started.
Does the pond have an outflow, or does it remain stagnant most of the time?
The pond does have both inflows and outflow through the salt marsh. Originally 2 ponds were dug – one large and one small. The small pond was dug to about 8 feet deep as I understand it and was intended to prevent salt water from moving into the large pond by capturing it. It has since filled in so some salt water is making it in to the large ponds, but they are still predominantly fresh. The mouth of the outflow gets clogged sometimes and the pond does start to stagnate, but part of my job is to make sure that gets cleared out when that happens.
Who are the stakeholders of this project? (i.e. Who has a say and stands to benefit from the final product)
The primary stakeholder is Morro Coast Audubon Society, but other parties likely to be involved are CA Dept of Fish & Game, Morro Bay National Estuary Program and TooSLO (an organization dedicated to turtle & tortoise conservation). Environmental benefits, should the project succeed, will accrue to the community as a whole and to state and national efforts to preserve biodiversity.
Are there any other students/groups/individuals working on this project as well?
Currently, I do have 2 Cal Poly students doing water quality monitoring in the ponds who will be doing this for a couple more quarters. This is fortunate, because we now have good baseline data to measure improvement against.
The ponds have become very anaerobic over the years due to the large amount of eucalyptus debris that falls from trees overhead and decomposes in the water. This makes it very difficult for freshwater organisms to survive at all levels of the food chain. Dredging the pond would certainly be another option, but it would be extremely expensive. It would also require pulling out existing fencing to get large equipment in, and would likely cause extensive damage to trails and vegetation. It is also unlikely that we could get permits to do it that way as threatened and endangered animals would be put at risk.
What species of animals inhabit the pond, and why are the turtles significant?
The southwestern pond turtle is the only freshwater turtle found in the State of California. It is currently considered a species of special concern by the CA Dept of Fish & Game. We are seeing little recruitment of young turtles at Sweet Springs. Although we have not done a comprehensive analysis to determine the causes, there are likely many factors at work – predation from native & nonnative species (e.g. raccoons, water fowl, bullfrogs, etc.), insufficient sun/warmth from shading, insufficient food from poor water quality and illegal collecting. We have not done recent wildlife surveys to identify all of the animal species that inhabit the ponds, but historically there are a wide array of bird species and a limited number of frogs, fish and macro invertebrates.
How deep is the pond and how much does the water level fluctuate throughout the year?
We haven’t taken any recent depth measurements and it is filling up with sedimentation. There is one relatively deep channel in the center that is 4-5 feet. Most of the pond is relatively shallow – less than 3 feet. It fluctuates considerably during low and high tides. I think we would probably want to take some new depth measurements before we get started.
Does the pond have an outflow, or does it remain stagnant most of the time?
The pond does have both inflows and outflow through the salt marsh. Originally 2 ponds were dug – one large and one small. The small pond was dug to about 8 feet deep as I understand it and was intended to prevent salt water from moving into the large pond by capturing it. It has since filled in so some salt water is making it in to the large ponds, but they are still predominantly fresh. The mouth of the outflow gets clogged sometimes and the pond does start to stagnate, but part of my job is to make sure that gets cleared out when that happens.
Who are the stakeholders of this project? (i.e. Who has a say and stands to benefit from the final product)
The primary stakeholder is Morro Coast Audubon Society, but other parties likely to be involved are CA Dept of Fish & Game, Morro Bay National Estuary Program and TooSLO (an organization dedicated to turtle & tortoise conservation). Environmental benefits, should the project succeed, will accrue to the community as a whole and to state and national efforts to preserve biodiversity.
Are there any other students/groups/individuals working on this project as well?
Currently, I do have 2 Cal Poly students doing water quality monitoring in the ponds who will be doing this for a couple more quarters. This is fortunate, because we now have good baseline data to measure improvement against.