Sparrows and Canaries
Water managers and innovators are only as good as the data they have and the tools they can use, and when it comes to today’s toughest challenges–such as nutrients–they need all the help they can get to monitor, model, assess and predict.
The U.S. Geological Survey (USGS) helps in many ways but one of the most important is its National Water Quality Assessment program (NAWQA). Begun in 1991, the program is meant to provide an accurate picture of water quality status and trends in river basins and aquifers and help answer the big question: Is quality improving or degrading? During its first two decades, the NAWQA program documented that while most water is fit for many uses, contamination from point and nonpoint sources affected surface water and ground water in every study unit. Valuable data has emerged on nutrients, pesticides, organics, and their breakdown products in urban and agricultural areas. The program also identified improvements in the nation’s water quality.
Along the way, the need for robust extrapolation and inference-based techniques became painfully clear as the money and people to do actual monitoring became (and continue to be)increasingly constrained (a statement of fact that applies to state and local agencies as well). In response, NAWQA developed and applied the Spatially Referenced Regressions On Watershed attributes (SPARROW) model to predict conditions at unmonitored stream locations. To speak in technical USGS jargon: The core of the model consists of a nonlinear regression equation describing the non-conservative transport of contaminants from point and nonpoint sources on land to rivers and through the stream and river network.
Why is it important and why has it been so controversial? Since its development in 1997, the SPARROW model has been used for predicting nutrient loadings and impacts in the Mississippi/Atchafalaya River Basin. In an effort to reduce the hypoxic zone in the Gulf of Mexico, the 2008 model was used to identify the top 150 watersheds for more targeted action on nutrients. “Targeting” makes sense but it’s also a four-letter word for some, particularly for those who feel they’re being identified as major contributors of nitrogen, unfairly and inappropriately. The Gulf Hypoxia Task Force‘s 2008 Action Plan recognized the importance of modeling and targeting and referenced the priority watersheds identified under SPARROW. Scientific and policy debates ensued.
There are legitimate concerns surrounding SPARROW and the use of modeling, more generally. SPARROW models don’t always rely on the most up-to-date data based on the nature of the beast. For example, nutrient yields from 10 or more years ago can be used in a model. Even more basic: Uncertainty is inevitable and runs throughout models, including SPARROW. Scientists simply don’t know all that’s happening in the environmental processes affecting the watersheds and the sources of nutrients and sediments. Atmospheric deposition, point sources, nonpoint sources, the role of reservoirs regarding phosphorus delivery, etc.
A lot has happened since 2008 in the efforts to understand and reduce nutrient loadings to the Gulf. For example, work continues to improve upon valuable modeling tools such as SPARROW. Groups are also taking some worthwhile steps for stewardship. The Fertilizer Institute, which continues to review the SPARROW model and its use by policy makers with some suspicion, has also launched a worthwhile education program, called 4R Nutrient Stewardship (choosing the Right nutrient source to apply at the Right rate in the Right place at the Right time).
One of the Alliance’s goals is to bring together agricultural and municipal leaders to find common ground on nutrients and water quality, whether the topic is science, stewardship, or regulation. It’s no surprise, though, that upfront disputes occur over the quality of data feeding into the SPARROW model and other potential targeting tools. A modeling tool is only as good as the data you put into it.
Whether it’s sparrows on a computer or canaries in a coal mine, the intent is the same: to help scientists, managers, and policy makers understand what’s happening and what’s likely to happen so that smarter decisions can be made in the future.
That’s why it’s important for Congress to provide adequate funding for USGS’s NAWQA program as it moves into its third decade. SPARROW is a valuable product that can become even more valuable with experience and collaboration. The Alliance recently joined twenty other national organizations in writing to House and Senate appropriators to resist substantial budget cuts to USGS’s NAWQA program. Essentially, core funding for basic monitoring and modeling programs can help connect the dots and drops, and inform local, state and federal managers on how best to target their resources effectively, efficiently, and equitably.