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 NO 3 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