Sonoma County Gazette, April 2013

Nutrient Reduction Programs Currently Center Stage

Laguna & Russian River are loaded with nutrients….

In August, 2009, when the lower Russian River was running at less than 50 cubic feet per second (125 cfs is normal) as measured at the Hacienda Bridge, algae and invasive Ludwigia were visible almost everywhere.  Clumps resembling turds floated on the water’s surface, and snaky plants with long arms branched out from the bottom where they were attached and felt slimy to the feet, as chartreuse moss clung to pebbles and stones, and invasive Ludwigia hugged the river’s shore for miles on end.  (See 2009 Photo Project at

Excessive nutrients, in this case mainly nitrogen and phosphorus, significantly stimulate algal growth and have the potential to enormously degrade water quality, especially during hot, low flow conditions.  These nutrients can bind with sediments and travel great distances downstream to be later deposited and released in other environments.

One formal definition on the web described it this way:  “Within the past 50 years, eutrophication—the over-enrichment of water by nutrients such as nitrogen phosphorus—has emerged as one of the leading causes of water quality impairment. The two most acute symptoms of eutrophication are hypoxia (or oxygen depletion) and harmful algal blooms, which among other things can destroy aquatic life in affected areas.”

Urban and rural sources contribute to Laguna nutrients…..

The Laguna de Santa Rosa, a fourteen mile channel draining a 254 square mile area, conjoins with Mark West Creek watershed and merges with the Russian River just upstream of Mirabel, and is a prime source of nutrients in the lower river.  The Laguna drains most of the Santa Rosa Plain, and includes all or part of the communities of Windsor, Santa Rosa, Rohnert Park, Cotati, Forestville, and Sebastopol.  Commonly, large amounts of nutrients and other toxins pour into our streams from urban runoff.

The Laguna floodplain is a vastly altered system that years ago was channelized to drain the land as riparian forests were cut down to accommodate agricultural activities, formerly broad lake bed areas were narrowed, and natural drainage generally lost its ability to absorb pollutants. Sediments have filled the formerly deepened channels, and Laguna flood capacity has diminished over the years. For example, Santa Rosa’s Treatment Plant on Llano Road, thought to be on high ground, flooded extensively for the first time New Year’s Day in 2006.  The plant was almost incapacitated during that event.

Wastewater discharges have historically been responsible for significant amounts of Laguna nutrient pollution, probably exceeded only by the storm water runoff containing nutrients from animal waste, fertilizer applied to ag lands and urban landscapes, toxins from roads and cars, and much more.

Ludwigia abounds along with low dissolved oxygen…..

In some locations, the Laguna and its tributaries are so filled with Ludwigia that creatures can walk across the broad swath of almost solid vegetative matter.  When this matter decomposes it diminishes dissolved oxygen necessary for aquatic life, and can make survival difficult, if not impossible for cold water fish and other species.  This excessive growth has been defined as a nuisance by the Regional Water Quality Control Board (Regional Board).

Regional Board develops TMDL….

In the meantime, nutrient loadings in the Laguna area are currently being studied by Regional Board scientists.  Unfortunately, there is not much baseline information available on past loadings.  Staff at this Agency are assessing nutrient loadings by land use type and will ultimately allocate total daily maximum loads, otherwise known as TMDL’s.  Improvements upstream will help alleviate algal blooms in the lower river area.

Load allocations will be developed for each contributor stating specific amounts of nitrogen and phosphorus that can be discharged.  In the case of phosphorus, none will be allowed without an offset project.  Santa Rosa will be held responsible for removing a comparable amount of nutrients that are currently not otherwise regulated.  The amount would be equal to the load allocation of the TMDL.

Santa Rosa required to meet ‘no net discharge of nutrients’…..

Several years back, the Regional Board declared that the City of Santa Rosa had three years to develop a plan to meet a new goal of ‘no net discharge’ of nutrients.  They were required to either get the nutrients out of their wastewater discharges, stop discharging into the waterway, or develop a program of nutrient offsets to be approved by the Regional Board.

The City filed a lawsuit protesting the requirement, but they ultimately lost, and the requirement is being retained in the new discharge permit currently being reviewed. Since 2004, Santa Rosa has been sending most of their wastewater either to the Geysers, or irrigating both urban and rural landscapes, so current discharges are far less than they used to be.  (Nutrient limits are another important reason to prevent irrigation runoff.)

(In dry years Santa Rosa often does not need to discharge at all, and circumstances are driven by the amount and timing of rainfall.  Flow is unpredictable, and usually in wet years, they do need to discharge.  For permit compliance, discharges are averaged over three years, and amount of nutrient offset based on a formula that estimates amount of nutrients discharged ON AVERAGE, whether or not they actually end up in the water.)

Santa Rosa develops nutrient offset projects….

After estimates of the average number of pounds of nutrients discharged by Santa Rosa were calculated, several alternatives were studied that, in combination, would offset those amounts.  While several proposed projects were rejected, three projects were accepted and approved by the Regional Board.  (Environmentalists had concerns about the eligibility of selected projects which we won’t detail here, but Regional Board staff promised that future projects would address environmental concerns that were raised in past comments.)

The City, along with the Regional Board staff, various consultants, local Resource Conservation Districts, and RRWPC have started looking at developing a nutrient credit trading program that would eventually allow dischargers to pay for restoration and/or nutrient removal projects and receive credits for doing so.  This project should be complete by October of 2014.

Finally, the State Board is requiring the development of a Salt and Nutrient Management Plan by those entities irrigating with recycled water.  Santa Rosa has begun the process, but progress has stalled in anticipation of an important groundwater study by the U.S. Geological Survey.  Hopefully, all of these studies and regulatory actions will converge to help restore the Laguna and Russian River where nutrients are concerned.