Agreement by and between
Sonoma County Water Agency
and the City of Santa Rosa for
Water Quality Trading
Framework (Phosphorus)
Contract Review Subcommittee
May 1, 2024
Overview
• Brief history of phosphorus requirements
• Agreement with Sonoma Water
• Next Steps
2 Phosphorus Regulatory
Requirements
• 2006 Permit: Nitrogen &
Phosphorus Zero Net Loading
• 2008 RWB Approves Nutrient
Offset Program (NOP)
• 2009-present: City implements
NOP Projects
• 2013 Permit: Zero Net Loading
for Phosphorus only
• 2018 RWB Adopts Water Quality
Trading Framework – Includes
Windsor Treatment Plant
Phosphorus Compliance
Strategy
1. Maximize reuse/minimize discharges
2. Decrease phosphorus in recycled water
3. Offset discharges via Water Quality Trading
Framework
4 Nutrient Offset Projects Implemented
1) Beretta Dairy –
Manure & Pasture Management
2) Pepperwood Nature Preserve –
Road & Drainage Improvements
3) Ocean View Dairy –
Manure Removal & Land Application
4) Laguna 1 and 2 –
Creek restoration and sediment removal
Cost of Projects
Project Cost
Total Sum of
Phosphorus
Credits
Cost per
Credit
Beretta $508,250 7,600 $67
Pepperwood $512,850 10,964 $47
Ocean View $474,000 23,345 $20
Laguna 1 and 2 $950,000 19,000 $50
Future Projects Cost and credits will vary >$67
Colgan Restoration Project
9 Phosphorus Credit Summary
• Project generated 19,049 credits
• Sonoma Water made 16,049 available for the City to
purchase
• Credits last for ten years
• Sonoma Water is charging $60 per credit for total cost of $962,940
• City received a credit of $10/cubic yard of soil received.
City received 18,585 cubic yards providing discount of
$185,850.
• Total contract: $962,940 - $185,850 = $777,090
10 Phosphorus Credit Balances
Credit Category Amount
Existing 5,351
Used this year 4,982
Remaining credits 369
Estimate from existing projects 700
Colgan Creek reaches 1 and 2 16,049
Total credits with project 17,118
11 Recommendation
• It is recommended by Santa Rosa Water that the
Contract Review Subcommittee recommend to the
Board of Public Utilities approval of the Agreement
by and between Sonoma County Water Agency and
the City of Santa Rosa for Water Quality Trading
Framework (Phosphorus)
12