Sb Evalucion

Christopher F. Knud-Hansen, Ph.D., CLM Limnologist & Certified Lake Manager SolarBee, Inc. 11867 Bradburn Blvd., Westminster, CO 80031 (866) 469-9606 • (303) 469-9606 • Fax (303) 469-4701

http://www.solarbee.com

Main Office and Service Center SolarBee, Inc. 3225 Highway 22, Dickinson, ND 58601 (866) 437-8076 • (701) 225-4495 • Fax (701) 225-0002

MEMORANDUM To: From: Date: ProspectiveSolarBee clients and customers Christopher F. Knud-Hansen, Ph.D., Certified Lake Manager (CLM) February 1, 2011

Re: Evaluating SolarBees in freshwater ponds, lakes, and reservoirs ____________________________________________________________

__________________

Field Evaluation of SolarBees in Freshwater
Background Research during the 1960s and early 1970s empirically documented theconnection between human activities, nutrient loading, and lake eutrophication. Through these studies, three features of eutrophication became evident: 1) the availability of soluble phosphorus is often a driving force behind unwanted algal blooms during periods of summer stratification, 2) summer harmful algal blooms (HABs) are typically dominated by inedible, toxic blue-green algae (cyanobacteria), and3) the settling and decomposition of blue-green algal blooms causes the deoxygenation of bottom waters during periods of summer stratification. These events can cause fish kills at fall turnover, as well as promote taste and odor issues in raw water supply reservoirs. With visions of Lake Tahoe water clarity, the history of lake management over the past 30-40 years has been generally one of crisismanagement and unfulfilled hopes. Lake managers have worked diligently to try and improve lake ecology and water quality over the years. Unfortunately, available technologies had limited capabilities. Aeration can increase dissolved oxygen (DO) concentrations in bottom waters, but bubbles rising to the surface also transport algal nutrients increasing the likelihood for a HAB. Phosphorus (P)inputs to a lake can be reduced by good watershed management, but the difficulty and costs of managing/treating non-point sources (e.g., agricultural and stormwater runoff) can be huge. Watershed stewardship is very important, but it just has not been very effective at controlling HABs. In-lake P inactivation with chemicals (e.g., alum) can provide short term (typically 2-5 years) relief, but itseffectiveness diminishes rapidly in lakes with high external inputs of P and/or when lake sediments are stirred up by wind mixing or bottom-dwelling fish. Subsequent alum applications are a question of when, not if, and when is often determined by how soon HABs return. Or, HABs can be dealt with directly with algaecides (e.g., copper sulfate). The problems here, however, are that algaecides kill a lotmore than just HABs, and some algal species responsible for HABs are gaining resistance to some algaecides, so

Memo (Feb. 1, 2011): Field Evaluation of SolarBees in Freshwater

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the water has to become even more toxic to be effective. Furthermore, benefits can last only weeks while lake ecology and biodiversity suffer with each application. On the other hand, circulation hasshown to be effective at preventing HABs in small water bodies, but had not been effectively applied to large lakes. Aeration used for circulation has had some success in small lakes and ponds, but the energy costs and practicality of installing/maintaining sufficient aerators often prohibit this approach for larger lakes. Furthermore, if aerators are placed in anoxic bottom waters, they cantransport nutrients into upper, photic waters promoting HABs if mixing is insufficient to stop their growth. In 1998, a solar-powered, up-flow circulation pump was developed by Pump Systems, Inc., a company from Dickinson, ND with a nearly 30-year history of success in the pump industry, and the company from which SolarBee, Inc. evolved. This circulator, called the SolarBee!, was developed to assist...