Greetings, 

A lined pond can use emergent native plants to help reduce algae, but our guidance emphasizes choosing non‑aggressive species and containing them in pots or fabric planters. 

Guidance from OSU Extension on Aquatic Plants in Ponds
OSU Extension’s pond management publications note that:
(Sources can be found here: 
https://extension.oregonstate.edu/water/ponds)

• Emergent plants can help reduce algae by absorbing excess nutrients.
• Plants should be placed in containers in lined ponds to prevent root penetration and to control spread.
• Species selection matters because some natives can become aggressive colonizers in small ponds.

Source: OSU Extension, Managing Pond Plants & Algae (EC 1635) 

Eleocharis palustris (Common spikerush)
OSU wetland plant guides describe this species as a clumping, non‑aggressive emergent suitable for shallow water and nutrient uptake. It performs well in containers and is appropriate for lined ponds.
Source: OSU Extension, Plants for Willamette Valley Wetlands (EM 9136)

Sagittaria latifolia (Broadleaf arrowhead / wapato)
Extension resources identify this as a stable, manageable emergent that spreads moderately by rhizomes but remains controllable in pots. It is widely used in restoration and water‑quality plantings.
Source: OSU Extension, Plants for Willamette Valley Wetlands (EM 9136)

Scirpus microcarpus (Small‑fruited bulrush)
Listed by OSU Extension as a tall but non‑invasive emergent, effective for nutrient uptake and appropriate for containerized use.
Source: OSU Extension, Plants for Willamette Valley Wetlands (EM 9136)

Alisma triviale (Northern water plantain)
OSU wetland plant descriptions note that Alisma species can spread readily by seed in shallow water and disturbed sites. In small ponds, this can lead to unwanted colonization, even when contained.
Source: OSU Extension, Plants for Willamette Valley Wetlands (EM 9136)

Extension‑aligned recommendation:
Use Eleocharis palustris, Sagittaria latifolia, and Scirpus microcarpus as primary algae‑reducing plants. Avoid or limit Alisma triviale if you want low maintenance and minimal spread.

For local pond, native plant, and water‑quality support:

• OSU Extension – Jackson County
  
  https://extension.oregonstate.edu/mg/jackson
  
  
• Land Steward / Natural Resources Programs in Jackson County https://extension.oregonstate.edu/land-steward/land-steward-training-courses