The Tumblin Creek watershed, encompassing 3.8 square miles of urban land, flows through south-central Gainesville to Bivens Arm Lake. Shands at Alachua General Hospital (AGH), Tumblin Creek Park, and P.K. Yonge Developmental Research School at the University of Florida are located within this watershed. The dominant land uses in the Tumblin Creek watershed are primarily residential, commercial, and institutional. The creek begins approximately 100 feet north of SW 5th Ave and flows an estimated 1.7 miles southward into Bivens Arm Lake just west of US 441. Sources of baseflow include springs and seeps from surficial aquifers. The headwaters, located are channelized through underground concrete culverts until the stream emerges from a 60-inch reinforced concrete pipe culvert at the
southern end of the Shands at AGH parking area. At the end of SW 7th Terrace, a 72-inch RCP culvert provides a second source of baseflow to Tumblin Creek.

FLORA AND FAUNA
The Tumblin Creek watershed is highly urbanized and almost completely developed. Except for the concrete and dredged channel segments, most of the creek displays a moderately shaded canopy. Tumblin Creek Park and the Bivens Arm forested wetland are good places to visit Tumblin Creek. Birds such as the red-bellied and red-headed woodpeckers, barred owls, and red-tailed hawks have been seen on numerous occasions near the Tumblin Creek Park, while belted kingfishers travel the nearby stream channel between Depot and SW 16th avenues. The Bivens Arm forested wetland supports the most diverse wildlife in the basin, including osprey, hawks, and alligators. Many of the large trees that can be seen along the stream are native and include water oak, sweetgum, cabbage palm, and loblolly pine. Camphor tree, although not native, is also common in the watershed. Certain opportunistic native plants such as southern elderberry and Carolina willow further characterize the nature of the watershed, but the majority of the understory vegetation surrounding the creek is exotic. Mexican petunia is the dominant plant seen along the stream’s edge, though glossy privet and coral ardisia are also quite common near the stream channel. Aquatic vegetation, both submergent and emergent, is practically nonexistent through-out Tumblin Creek. The exception is the Bivens Arm forested wetland which, in some places, is covered with the native wetland emergent plant golden club.

WATER QUALITY
Because Tumblin Creek flows through mostly urban and developed areas, the major source of nonpoint source pollution is runoff from the impervious areas in the watershed. Over 60% of the creek watershed has impervious surfaces. Stormwater runoff is therefore a major pollution concern. Further, many of the stream segments in Tumblin Creek lack an effective riparian buffer. This combination of large areas of impervious surfaces along with the absence of riparian buffers allows fertilizer and pesticide runoff to flow directly to the creek. Street stormwater containing petroleum products, antifreeze, and sediments also washes directly into Tumblin Creek during rain events. Another pollution concern is the consistent high levels of fecal coliform bacteria present. While several point sources have been discovered and remedied, these high levels still persist. Possible sources include runoff from animal and human activity, leaking septic tanks, leaking sanitary sewer lines, and failing private connections to the city’s sewer lines.

MACROINVERTEBRATES
The health of streams can also be evaluated by determining the number of pollution-sensitive benthic macroinvertebrate organisms present. These organisms, such as snails, crawfish aquatic worms and the larvae of dragonflies and damselflies, are susceptible to degradation of water, sediment, or habitat quality and their populations respond to these cumulative factors over time. Macroinvertebrates are also important food sources for adult insects, fish, frogs and birds.
Most of Tumblin Creek lacks adequate habitat to support a diverse benthic macroinvertebrate community due to erosion and sediment deposition. In-stream erosion is a serious problem in the upper portions of the watershed while sediment deposition is the prevailing issue in the lower reaches. Deposited sediment mobilizes during storm events and drops out further downstream. Without a stable substrate, in-stream aquatic vegetation is largely non-existent. Sand smothering of the streambed is common, occurring even in the natural, forested areas of the watershed.

Tumblin Creek, Gainesville, Florida