How much water comes off the hills?

Posted on Categories News

WSU researcher Ani Jayakaran works with Pierce County staff and Kristin Williamson of South Puget Sound Salmon Enhancement Group to determine an ideal location for a stream gauge on the Clear Creek tributary.

In the past few years, one consistent question from farmers and residents in the Clear Creek area has been: How much water is coming off the hillside from Waller and surrounding areas? We know a lot of development has occurred, and it seems like there is an increasing flow of water onto our land!

The excess water- some of it stormwater runoff from development upstream– ponds on agricultural land, making it dicey for farmers to get onto the land in time in early Spring to plant a first round of crops. Poor drainage in the Clear Creek area exacerbates the situation, meaning that farmers often find themselves with soggy land much later in the season than they’d like!

The water is likely coming from different sources- precipitation, of course, but also high groundwater levels, poor drainage throughout the system, and some proportion of the water is running off the hillside’s impervious surfaces, entering the four creeks (Canyon, Clear, Squally, and Swan) and flowing into the floodplain below. This last piece is one question we’re interested in answering!

In April 2019, a team from WSU Puyallup, South Puget Sound Salmon Enhancement Group, and Pierce County explored possibilities for placing stream gauges on each of the four creeks. Combined with a stream survey, data from the gauges could be used to calculate approximately how much water is flowing off the hillside onto the land below. This information will be used to help the Floodplains for the Future partnership determine whether sediment ponds or other flow-control methods (like installing sediment traps or large woody debris to trap material, slowing flow downstream) might benefit the land below. The end goal, from an agricultural perspective, is to minimize the impact of stormwater runoff on agricultural lands, allowing our local farmers to use their land more productively to produce our food! 


Installation of gauges will be happening soon, and data should start rolling in thereafter- we’ll need about a year’s worth of flow data to get a sense for the answers we need. Building a better picture of the hydrology of the Clear Creek system will help all of us understand specific actions we can take to improve drainage!