TPWD to publish petitioned proposal to allow enclosed dotted‑duckweed aquaculture with strict biosecurity and exclusion zones
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Summary
TPWD will publish for public comment a petition to allow commercial production of dotted duckweed in enclosed, department‑permitted facilities under strict biosecurity (greenhouse containment, mandatory maceration of drainage, on‑site processing and exclusion zones).
Texas Parks and Wildlife staff presented a petition and draft rule language on Nov. 5 to allow commercial aquaculture of dotted duckweed (an exotic duckweed species currently listed as a controlled exotic aquatic plant in Texas) under strict, facility‑level biosecurity measures.
Michael Tennant (Regulations and Policy) reviewed the species' biology, uncertainty about invasive behavior (USFWS risk assessment classified risk as uncertain), and the petitioner's industry case: dotted duckweed produces high protein biomass and can be attractive for plant‑based foods and feed. Tennant said dotted duckweed has high climate suitability across most of Texas and that seeds can be drought tolerant and survive dry conditions, posing dispersal risk by waterfowl and by floodwaters.
Given those risks, staff proposed special provisions for any permitted, commercial dotted‑duckweed facility: full enclosure of culture ponds and harvesting/processing equipment in greenhouses or other structures; routing pond drain water and processing effluent through a department‑approved macerator or device that reduces plant material to particles no larger than 100 micrometers (nonviable); on‑site processing only; prohibitions on discharge to ditches, storm drains or conduits that could reach public waters; and exclusion from a coastal/eastern zone (staff proposed south of State Highway 21 east of I‑35, with an alternate larger exclusion map shown). Staff noted those measures reflect facility features already present or agreed to by the petitioner and would require inspections prior to permit issuance and at least once per five years plus discretionary spot inspections.
Commissioners expressed concerns about permitting an exotic that matches Texas's climate well and about the small‑water, community lakes most at risk if escape occurred. Some commissioners urged greater exclusion zones or higher inspection frequency; others asked for the petitioner and supportive legislators to appear at the January adoption meeting. After discussion, Chairman Foster authorized staff to publish the proposal in the Texas Register, with the added definition change for aquatic plants staff proposed.
Why it matters: Dotted duckweed is a high‑growth exotic species with uncertain invasion history and potential to form dense mats in small still waters; the proposed approach attempts to balance economic opportunity for a nascent industry with biosecurity requirements to minimize escape risk and environmental harm.
What's next: The rule package and definition change will be published for public comment; staff will collect feedback and return to the commission for consideration at the adoption stage.
Attribution: Michael Tennant, Regulations and Policy Coordinator, presented the petition and proposed special provisions; commissioners debated exclusion zones and inspection frequency.
