Cottonwood Creek Water Quality

Public Comment Period

The public comment period is now closed.

DEC has developed a water body recovery plan, called a Total Maximum Daily Load (TMDL) and is asking for your input. The plan is designed to improve water quality in Cottonwood Creek. The plan emphasizes cleaning up possible fecal coliform bacteria sources while also preventing new sources.

Cottonwood Creek is polluted due to excessive and persistent fecal coliform bacteria. The source of the pollution is rainwater and snow melt coming in contact with the bacteria then flowing to the creek. The State of Alaska included 7 miles of Cottonwood Creek on the impaired waters list based on several years of fecal coliform bacteria sampling.


Cottonwood Creek is a 39.4 square mile (mi2) spring-fed watershed located near Wasilla in south central Alaska in the Matanuska-Susitna Borough. Cottonwood Creek is 13 miles long and flows through several lakes, subdivisions and road crossings before emptying into the Knik Arm of Cook Inlet.

Water Quality Impairment

The Department of Environmental Conservation (DEC) has several years of fecal coliform bacteria data for Cottonwood Creek. In 2010 the DEC listed Cottonwood Creek on the Clean Water Act Section 303(d) list (Category 5) as an impaired waterbody for fecal coliform bacteria pollution. The presence of fecal coliform bacteria indicates an increased risk of pathogen contamination in a waterbody. Consumption of or contact with pathogen contaminated waters can result in a variety of gastrointestinal, respiratory, eye, ear, nose, throat and skin diseases.

The impaired section of the creek is 7 miles long extending from downstream of the Parks Highway crossing all of the way downstream to Surry Road. In 2010, DEC completed a microbial source tracking project, "Fecal Coliform Bacteria Source Assessment in the waters of Cottonwood Creek, Wasilla and Little Campbell Creek, Anchorage", that, through DNA markers, identified some of the bacteria in the creek as human in origin.

Current Activities

DEC is currently working with partners to implement several of the actions described in the water body recovery plan. Specifically:

Cottonwood Creek Sampling
  • Cottonwood Creek Septic Cooperatives – a program where several homeowners pump their septic system at one time and receive a discount. Contact Catherine at 841-2226.
  • National Water Quality Initiative – a federal program that works with landowners who have livestock to improve water quality in runoff. Contact Keith at 373-6492 x 101.
  • Streambank Restoration – a federal program with funding opportunities for creek-side homeowners to conduct streambank restoration to improve the vegetated buffer area. Contact Elizabeth at (907) 271-2718.

In addition, the Matanuska Susitna Borough recently adopted a Stormwater Management Plan. Many of the voluntary activities which the borough and others will be undertaking will assist in improving the water quality of Cottonwood Creek by reducing the amount and types of pollutants entering the creek’s water.


Laura Eldred
1700 E Bogard Rd, Bldg B, Ste 103
Wasilla, AK 99654
Phone: (907)376-1855

Of Interest

Cottonwood Creek Map Map illustrating the water quality impaired section of Cottonwood Creek (purple line) downstream of the Parks Hwy. to Surry Rd Hwy