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HELPING NATURE’S BALANCE
by Mark Webb, TPWD and  Jace Houston, SJRA

Lake Conroe’s ecosystem – a balance of native vegetation, numerous species of fish (including grass carp), and minimal invasives (hydrilla, giant salvinia, water hyacinth) – requires constant human monitoring.

Lake Conroe is a living ecosystem, with its own aging process, chemistry, different species of biological and botanic life, and its own unique hydrology. Everyone who relies on the lake – from fishermen to homeowners to recreational visitors to naturalists or just plain tourists – has his own set of expectations that all these systems will function in sync and will continue to enhance the human experience. From a lake management point of view, that means that the body of water must be capable of meeting the needs of such diverse stakeholders as property owners, boaters, fishermen, and jet skiers, while accommodating potable water demands of municipal customers downstream.

The skill sets involved in the science of managing our environment are constantly evolving. Since it is almost always easier to accomplish a goal in a laboratory’s controlled environment than it is to duplicate it in the real world, environmental managers soon learn to temper good intentions with hands-on observation and experimentation. With a sound background in both science and practice, the San Jacinto River Authority and the Texas Park and Wildlife Department (TWPD) have formulated a plan to sustain the delicate balance between the lake’s natural systems and human needs.

Re-introducing ‘old friends’…

Extending the lake’s successful aquatic plant management progress to date, we will begin re-introducing some hearty, native, aquatic plants late this summer or early fall. These plants will likely include a number of selected species from below:
 

Click on the image below for details on each native plant. (pdf documents)

Common Name

Wild Celery

 American Pondweed Illinois Pondweed
 

Wild Celery

 American Pondweed Illinois Pondweed
Scientific Name Vallisneria americana Potamogeton nodosus P. illinoensis
Growth Form Submersed Submersed Submersed
       
Common Name Water Stargrass White Water Lily Spatterdock
  Water Stargrass White Water Lily Spatterdock
Scientific Name Heteranthera dubia Nymphaea odorata Nuphar luteum
Growth Form Submersed Floating-leaved Floating-leaved
       
Common Name Softstem Bulrush Water Willow Flatstem spikerush
  Softstem Bulrush Water Willow
Scientific Name Scirpus validus Justicia americana Eleocharis macrostachya
Growth Form Emergent Emergent Emergent
       
Common Name Squarestem spikerush Pickereweed Bulltongue
  Squarestem spikerush Pickereweed Bulltongue
Scientific Name E. quadrangulata Pontederia cordata Sagittaria graminea
Growth Form Emergent Emergent Emergent
       
Common Name Arrowhead Creeping burhead Water hyssop
  Arrowhead Creeping burhead Water hyssop
Scientific Name S. latifolia E. cordifolius Bacopa monnieri
Growth Form Emergent Emergent Emergent
       
       
Common Name Scientific Name Growth Form
Coontail Ceratophyllum demersum Submersed
Watershield Brasenia schreberi Floating-leaved
American lotus Nelumbo lutea Floating-leaved
Tall burhead Echinodorus berteroi Emergent
Slender spikerush E. acicularis Emergent
Maidencane Panicum hemitomon Emergent
     
These plants bring oxygen to the lake, they stabilize the lake bottom, they provide food and cover for the fish, amphibians, and aquatic insects, and – because they are natives – they produce much more manageable growth in local environs than the “exotics” and “invasives” that have created such problems over the years. Native plants have characteristics that function like natural “growth inhibitors” and keep them from spreading the way that invasives do. Natives generally require a stable environment that is protected from wind and wave action. Also, natives propagate much more slowly and typically only grow well in very shallow water.

Of course, these same “slow growth” characteristics that make natives beneficial for a healthy lake ecosystem also make them much more difficult and time-consuming to reintroduce, especially into a system that contains hungry grass carp. Until the carp population begins to decline, reintroduction of natives will generally be done in small areas using protective wire baskets. Also, species of natives that are “carp resistant” will be reintroduced first.

The San Jacinto River Authority and Texas Parks and Wildlife Department intend that the native plants being introduced will begin to slowly and gradually replace a portion of the hundreds of acres of native plants that have been damaged by grass carp in the effort to control hydrilla.
Monitoring will be routine and carefully conducted so that adjustments can be made to maintain the balance between grass carp, hydrilla, and native aquatic vegetation.

The important thing for all our various lake stakeholders to understand is that – like so many things in life – balancing this ecosystem is an ongoing work in process. Fortunately, it is a manageable process due to our current expertise and understanding. Thanks for your patience in working with us, and as the process unfolds, we’ll keep you informed!