CALIFORNIA ASSOCIATION OF RESOURCE CONSERVATION DISTRICTS

SHANNON SWEENEY, WATER RESOURCES MANAGER, CITY OF SANTA MARIA

ANNE COATES, CACHUMA RESOURCE CONSERVATION DISTRICT

THURSDAY,NOVEMBER 13, 2014

RETHINKING WATER:PROTECTING MUNICIPAL

WATER BY PASSIVELY TREATING AGRICULTURAL

RUNOFF

SANTA MARIA VALLEY GROUNDWATER BASIN

• BENEFICIAL USES INCLUDE:

• AGRICULTURAL SUPPLY

• MUNICIPAL SUPPLY

• GROUNDWATER BASIN CONNECTED TO SURFACE WATERS WITH BIOLOGICAL, RECREATIONAL USES.

• IMPACTED BY NITRATE, WHICH AFFECTS ALL OF THE BENEFICIAL USES.

CITY OF SANTA MARIA MUNICIPAL SUPPLY

• CITY OF SANTA MARIA HAS TWO SOURCES OF DOMESTIC WATER SUPPLY:

• STATE WATER: HIGH QUALITY, VARIABLE SUPPLY

• GROUNDWATER: VERY RELIABLE, VARIABLE QUALITY

• DOMESTIC SUPPLY NEEDS TO MEET STATE AND FEDERAL WATER QUALITY STANDARDS FOR NITRATE AND TOTAL DISSOLVED SOLIDS.

GROUNDWATER SUPPLY AND QUALITY

• CITY PRODUCTION WELLS HAVE VARIABLE QUALITY.

• TESTING SHOWS LOWER WELL PERFORATIONS

LOWER IN NO3 THAN

UPPER PERFORATIONS.

WELL 9 DYNAMIC FLOW PROFILING

RWQCB AGRICULTURAL ORDER

• FARMERS SEEK LOW NITRATE IRRIGATION WATER TO LOWER NITRATE IN RUNOFF, OR AVOID RUNOFF COMPLETELY.

• PROBLEMS – IF EVERYONE DIGS DEEPER WELLS, THEN “LOWER” AQUIFER BECOMES IMPACTED ALSO. LEAVING WATER ONSITE LEADS TO SALT BUILDUP – BAD FOR FARMERS AND MUNICIPAL SUPPLY.

• REGIONAL BOARD’S NUTRIENT CONCERNS: DOWNSTREAM BIOSTIMULATORY EFFECTS (ALGAL BLOOMS) AND RECHARGE FOR MUNICIPAL SUPPLY

UC DAVIS REPORT FOR THE SWRCB SBX2 1 REPORT TO

THE LEGISLATURE• 2008 – SBX2 1 SIGNED INTO LAW – REQUIRES A STUDY TO BETTER UNDERSTAND NITRATE ISSUES.

• FINISHED PRODUCT: ADDRESSING NITRATE IN CALIFORNIA’S DRINKING WATER.

• KEY FINDING: “DIRECT REMEDIATION TO REMOVE NITRATE FROM LARGE GROUNDWATER BASINS IS EXTREMELY COSTLY AND NOT TECHNICALLY FEASIBLE. INSTEAD, “PUMP-AND-FERTILIZE” AND IMPROVED GROUNDWATER RECHARGE MANAGEMENT ARE LESS COSTLY LONG-TERM ALTERNATIVES.”

Main Issue: How can farmers “pump and fertilize” without letting nitrate-impacted runoff affect downstream uses, while still removing salts?

One thought: If nitrate is removed from the runoff, then salts can move to a proper sink (the ocean!) and municipal supply can be protected from both salts and nitrate.

DRAINAGE

• MOST OF SM VALLEY DRAINS THROUGH DISCRETE POINTS TO SM RIVER.

• THESE DISCRETE PATHS LEND THEMSELVES TO TREATMENT LOCATIONS.

NUTRIENT REMOVAL• BIOLOGICAL TREATMENT FOR NUTRIENT REMOVAL IS COMMON:

• WETLANDS – NEED LARGE FOOTPRINT

• TERTIARY WWTP’S – LABOR INTENSIVE, LARGE CAPITAL INVESTMENT

• BIOFILTERS – PASSIVE TREATMENT, LOW FOOTPRINT

• SOLUTION NEEDS TO MAXIMIZE NITRATE REMOVAL WITH SMALL FOOTPRINT AND LITTLE INVOLVEMENT.

BIOFILTER CONCEPTS• FACULTATIVE ANAEROBES CONVERT AMMONIA TO

NITRATE WHEN OXYGEN IS PRESENT.

• SAME BACTERIA SCAVENGE OXYGEN OFF NITRATE IN THE ABSENCE OF OXYGEN. NITRATE IS CONVERTED TO NITROGEN GAS.

• PROCESS NEEDS A SUBSTRATE, A CARBON SOURCE, AND SUFFICIENT TIME FOR BACTERIA TO GROW AND METABOLIZE.

• CONSTANT FLOW AND NUTRIENTS HELP, TOO.

WOODCHIP BIOFILTER• WOODCHIPS PROVIDE THE

CARBON AND THE SUBSTRATE

• CITY & COUNTY SUPPORT INSTALLATION AT JIM MAY PARK, FOR TREATING WATER FROM BRADLEY CHANNEL.

• BRADLEY CHANNEL DRAINS 5,700 ACRES OF AG LAND, 913 ACRES OF URBAN LAND.

• FEASIBILITY STUDY COMPLETED. EXPECTED TO REMOVE UP TO 50,000 LBS NITRATE PER YEAR.

El Centro, CA

CAN THIS HAPPEN?

• FILTER IS A PHYSICAL SOLUTION IN NEED OF FUNDING.

• RCD GRANT HAS FUNDING NOT OTHERWISE AVAILABLE TO A MUNICIPAL AGENCY.

• RWQCB SUPPORTS THIS EFFORT.

JIM MAY PARK BIOFILTER

• TREATS AGRICULTURAL RUNOFF FROM 5700 ACRES

• 20 GAL/MIN WITH NITRATE EXCEEDING 80 MG/L

• EXPECTED REMOVAL OF UP TO 50,000 LB/YR NITRATE