Project 3: Turtle Ponds PhosLock Pilot

Phoslock is a patented phosphorus locking technology containing lanthanum (5%), a naturally occurring earth element, embedded inside a clay matrix (~95%). Phoslock has the capacity to bind phosphate when applied to aquatic environments and results in a non-toxic mineral that becomes an inert component of the sediments. For over ten years, Phoslock has been successfully used in water resource restoration programs around the world to remove free reactive phosphorus and restore water quality. Although Phoslock is a new technology to the United States (2010), it is rapidly emerging as an effective phosphorus inactivation and water quality restoration solution for ponds, lakes and reservoirs. Before a Phoslock project can be initiated on BCR, it needs to be tested under similar conditions as a pilot project. The BCWA proposes to apply a Phoslock treatment on the Turtle Pond in Bear Creel Lake Park as a short-term pilot project. The 2-acre Turtle Pond is adjacent to Turkey Creek and receives seepage from the creek, but is a contained system. The BCWA would conduct 3-4 month pilot project. The BCWA would monitor pond quality including sediment analysis prior to application with a 6 month follow up analysis of quality changes.

The Bear Creek Watershed Association (BCWA) has identified a problem of internal phosphorus loading in Bear Creek Reservoir. This internal loading contributes to eutrophication and excessive algal blooms. The reservoir standard for Chlorophyll a is 12.2 ug/l (chronic) = mean concentration measured through collection of samples that are representative of the mixed layer during summer months (July, August, September) and with an exceedance frequency of once in five years; and the standard for phosphorus is 22.2 ug/l (chronic) = mean concentration measured through collection of samples that are representative of the mixed layer during summer months (July, August, September) and with an exceedance frequency of once in five years. Neither of these standards can be consistently meet in the summer months. The reservoir is on the 303(d) list of impaired waters for chlorophyll and total phosphorus. Generally, the release of phosphorus from the bottom sediments is at a higher con-centration compared with inflow water concentrations. This internal loading is major contributor to the phosphorus standard exceedance and a principle driver phytoplankton growth, which causes the exceedance of the Chlorophyll standard. Reducing the internal loading of phosphorus is a critical management practice required for compliance. Phoslock is a Phosphorus Locking Technology that has the potential to significantly reduce the reservoir internal phosphorus loading. The BCWA will address permitting requirements and permissions with the Water Quality Control Division and U.S. Army Corps of Engineers. The BCWA and Lakewood staff in cooperation with EutroPHIX will conduct water quality and sedi-ment studies on the pond, This data would be used to determine the best dosing amount for the available mobile phosphorus. The BCWA will conduct a minimum of 5 monitoring events for total phosphorus, total nitrogen and soluble reactive phosphorus (orthophosphorus). The BCWA will monitor for field parameters including specific conductance, water and air temperature, dis-solved oxygen, pH and water flow, if applicable. The BCWA will collect bottom sediments for transport to EutroPHIX company for analysis of phosphorus content. After a dosing amount is determined, the BCWA, Lakewood staff and EutroPHIX will apply Phoslock to the pond. It is estimated that the dosing amount will be about 2,000 pounds/acre. After application, the water chemistry will be analyzed for a period of time up to 6-months. The frequency of analysis will depend on the pond response to the application. A photographic record of the pond response will be created.

The cost of the Phoslock (4,000 pounds) is about $7.200 plus shipping and application. The labor will be provided by the BCWA and Lakewood staff. The monitoring cost for the demonstration period (assuming 16 sample sets) for ortho phosphorus , total phosphorus, and total nitrogen is about $3,100. The sediment analysis is about $2,400. The estimated total pilot project cost is about $12,700.

The BCWA will monitor for field parameters including specific conductance, water and air temperature, dis-solved oxygen, pH and water flow. Laboratory samples will be collected for total phosphorus, orthophosphorus and total nitrogen. Sediment samples will be analyzed for phosphorus content. The BCWA will be able to determine load reductions from the pilot project and project future load reductions using Phoslock. Additionally, BCWA will determine the cost effectiveness of this nutrient reduction system.

This project will align multiple partners which include but not limited to Bear Creek Watershed Association, City of Lakewood, U.S. Army Corp of Engineers and EutroPHIX.