Sweetwater Authority tightens chemical specs to meet slashed California manganese limits

Sweetwater Authority tightens chemical specs to meet slashed California manganese limitsThe California utility approved $1.8 million in chemical supply contracts for FY 2026-27, updating its iron-based product specifications to keep treated water well below the state's newly reduced 50 ppb notification level for manganese.

The Sweetwater Authority Water Quality Committee approved $1.81 million across multiple vendors for water treatment chemicals, keeping overall costs flat year-over-year.

Specifications for ferric and ferrous chloride were tightened to limit manganese impurities following a state decision to drop the manganese notification level from 500 ppb to 50 ppb.

The committee also authorized $876,200 in SCADA contracts, which includes investigating a 1959-era electrical substation that could cost millions to replace.

In a bid to maintain compliance with tightening state water quality regulations, the Sweetwater Authority Water Quality Committee approved $1.81 million in annual water treatment chemical contracts on June 15, 2026, introducing stricter purity specifications for its iron-based coagulants. The updated specifications target the manganese content in ferric chloride and ferrous chloride. The move directly responds to the State Water Resources Control Board’s Division of Drinking Water (DDW) decision on June 2, 2026, to lower the manganese Notification Level (NL) from 500 parts per billion (ppb) to just 50 ppb. The Director of Water Quality noted during the meeting that while the authority is currently in full compliance with the new 50 ppb limit, trace amounts of manganese naturally occur in iron-based chemical products. By mandating lower manganese content from its suppliers, the authority aims to reduce the amount of the mineral inadvertently added back into the treated water, improving water color and providing "extra insurance" against regulatory breaches. Overall chemical procurement costs for the fiscal year stabilized at $1.81 million, matching the previous year's total. Staff noted this reflects improved market conditions compared to the volatility seen in previous years, despite ongoing fluctuations tied to tariffs and transportation costs. The authority is also exploring alternative algaecides, such as hydrogen peroxide-based products, for the Sweetwater Reservoir. However, after receiving no responsive bids for the alternatives, the utility will continue relying on industry-standard copper sulfate while updating its Aquatic Pesticide Application Plan. Alongside the chemical awards, the committee advanced $876,200 in automation and electrical design contracts for FY 2026-27. Enterprise Automation was awarded a $730,200 contract for SCADA integration, which will cover software upgrades and the modernization of communications at the Loveland Reservoir. The authority plans to replace an unreliable AT&T analog leased line with newer technology, potentially evaluating cellular or Starlink options. Additionally, Rockwell Construction Services was awarded $146,000 for SCADA design consulting. A key expense project under this contract is a $43,000 investigation into the Perdue Water Treatment Plant's 12-kilovolt electrical substation. The original 1959 equipment suffered an outage in March 2025. The Director of Water Quality warned that replacing the utility-owned substation through San Diego Gas & Electric would likely cost "in the millions of dollars," making a thorough maintenance and spare-parts investigation critical for near-term reliability.