Utilities Department
MEMO
TO: HONORABLE MAYOR AND CITY COUNCIL
FROM: STEVE POTTER, CITY MANAGER
CC: JOY ELDREDGE, UTILITIES DIRECTOR
DATE: August 24, 2026
SUBJECT: WRITTEN DETERMINATION TO ENTER INTO AN AGREEMENT WITH STILL WATER ECOSYSTEM, WATERSHED & RIVERINE SCIENCES dba STILLWATER SCIENCES FOR LAKE HENNESSEY WATER QUALITY IMPROVEMENT PROJECT
RECOMMENDATION
That the City Council receive and file this memorandum documenting the City Manager’s determination that the specialized consulting services for Phase I of the Lake Hennessey Water Quality Improvement Project qualify as a “specialty item” pursuant to Napa Municipal Code (NMC) Section 2.91.050, and that the City may enter into a contract with Stillwater Sciences without further compliance with the competitive procurement requirements of Chapter 2.91.
BACKGROUND
The City is seeking to improve the long-term water quality of Lake Hennessey, which serves as a critical source of the City’s drinking water supply. The City currently operates a pilot aeration system intended to minimize algae and cyanobacteria blooms that can affect water treatment, introduce cyanotoxins into the raw water supply, and produce taste and odor compounds such as geosmin and MIB. While the existing system, combined with periodic algaecide applications, has provided moderate success, it is considered an interim solution.
The City desires to evaluate permanent oxygenation approaches that could improve reservoir water quality and reduce or eliminate the need for periodic chemical algaecide applications. Phase I of the project will evaluate existing reservoir data, quantify sediment and water-column oxygen demand, evaluate commercially available oxygenation technologies, and develop a recommended conceptual approach for future design and implementation.
SPECIALTY ITEM DETERMINATION
Pursuant to NMC Section 2.91.050(A), the City Manager makes the following written determinations:
1. The project need which the City intends to satisfy through the contract for the specialty item.
The City requires specialized technical consulting services to evaluate the causes and contributing factors associated with harmful and nuisance algal blooms and taste and odor compounds in Lake Hennessey and to identify a technically appropriate long-term oxygenation strategy. The services require analysis of reservoir and water-quality data, evaluation of sediment and water-column oxygen demand, assessment of commercially available oxygenation technologies, consideration of site-specific operational and physical constraints, and development of recommendations that can serve as the basis for future design.
The work also requires specialized field and laboratory methods, including sediment oxygen demand and water-column oxygen demand testing, as well as an understanding of reservoir limnology, oxygenation systems, algae and cyanobacteria, geosmin and MIB production, and drinking water source-water quality.
2.The types of property or service which are available (or used by other similarly situated private or public agencies) to meet this need (or similar needs), and the contractors which are available to provide the property or service.
There are consulting firms that provide general reservoir, water quality, limnology, and engineering services. However, the City's needs require a more specialized combination of reservoir science, oxygen demand testing, oxygenation technology evaluation, and drinking water source-water expertise.
The City evaluated the availability of firms capable of providing these specialized services and considered the qualifications and experience necessary to complete the proposed work. Stillwater Sciences has assembled a specialized technical team with demonstrated expertise in reservoir oxygenation and water quality. The proposed team includes Dr. Marc Beutel, whose specialized methods and expertise will be used for the sediment and water-column oxygen demand evaluation, and Brown and Caldwell to provide supporting engineering expertise.
The City also considered the experience of other water agencies with similar reservoir water quality evaluations. Based on the City's review and discussions regarding comparable work, other agencies have utilized consultants for similar studies and subsequently relied on Stillwater Sciences to reevaluate or redo portions of the work due to the specialized expertise required.
3. The reasons why it is impracticable for a similar service to meet the City’s needs (including considerations of compatibility with other City services regarding maintenance, repair, training, quality, price, or similar considerations); or why the City’s needs can only be met by one unique or proprietary type of service (the specialty item).
Although other consultants are capable of providing general water quality, limnology, or engineering services, the City requires a highly specialized and integrated evaluation. The technical foundation of the project depends on accurately characterizing sediment and water-column oxygen demand and applying that information to the evaluation of oxygenation technologies and reservoir-specific water quality objectives.
Stillwater Sciences possesses the specialized staff, technical methods, and experience necessary to perform these interrelated services as a coordinated effort. Using separate consultants or a consultant without this specialized expertise would increase the risk of inconsistent technical approaches, duplication of work, additional costs, and the need for subsequent reevaluation of the work. The City's experience with similar studies performed for other agencies further demonstrates the importance of obtaining the required specialized expertise at the outset.
The proposed scope also requires the integration of reservoir science with engineering considerations. Stillwater Sciences will lead the technical evaluation, while Brown and Caldwell will provide high-level engineering support related to implementation constraints, costs, power availability, construction considerations, and other engineering issues. This integrated approach is necessary to develop a technically defensible recommendation for Lake Hennessey.
4. By entering into a contract for the specialty item from the proposed contractor, the City will meet the purpose and goals identified in NMC Section 2.91.010.
Entering into a contract with Stillwater Sciences will further the purposes and goals of NMC Section 2.91.010 by obtaining specialized professional services that provide the City with the best value and support responsible stewardship of public resources.
The proposed approach is intended to establish a sound technical basis for future capital investments in Lake Hennessey, reduce reliance on recurring chemical algaecide applications, improve source-water quality, and reduce the risk of investing in an oxygenation system that does not adequately address the City's water quality objectives.
5. The contract complies with the requirements of NMC Section 2.91.030 (B).
Pursuant to NMC Section 2.91.030(B)(2), (a) will be approved as to form by the City Attorney, (b) as determined by the City Auditor, there are sufficient unencumbered funds to cover the cost of the contract, which, will be funded by various capital and operating accounts, (c) the contract is prepared in accordance with all other requirements of this Code and the administrative regulations; and (d)(1) the Utilities Director will approve the public works contract.
CONCLUSION
Based on the specialized nature of the required services, the technical expertise necessary to perform the work, the qualifications of the proposed Stillwater Sciences team, and the experience of other water agencies with similar reservoir water quality studies, the City Manager determines that the proposed Phase I Lake Hennessey Water Quality Improvement Project services constitute a specialty item under NMC Section 2.91.050.
Accordingly, the City Manager has determined that Stillwater Sciences is uniquely qualified to provide the required services and that entering into the proposed contract satisfies the requirements of NMC Section 2.91.050. This determination allows the City to proceed with the specialty item contract without further compliance with the competitive procurement requirements otherwise applicable under Chapter 2.91.
This determination is limited to the specialized Phase I consulting services described above. Future phases, including conceptual design, detailed design, construction support, and implementation, will be evaluated separately in accordance with the City's applicable procurement requirements.
City Hall: 955 School Street, Napa CA 94559 ½ Mailing Address: P.O. Box 660, Napa CA 94559 ½ (707) 257-9500 ½ www.cityofnapa.org ATTACHMENT 2