Concrete control since Aug. 29, 1916. Prior to Oct. 1, 1928, non-recording gage at Walnut Street Bridge 600 ft upstream, and Oct. 1, 1928, to Aug. 31, 1975, water-stage recorder at site 3,170 ft downstream, all gages at same datum. Water temperature data collection at the City Island site was discontinued on March 25, 2015. Regulations and diversions from 15 flood-control reservoirs upstream, combined capacity of 1,571,000 acre-ft. WATER QUALITY DATA FROM THE WALNUT STREET PIER LOCATION IS SEASONAL AND IS NOT TRANSMITTED VIA SATELLITE TELEMETRY AND THEREFORE WILL ONLY BE UPDATED ABOUT EVERY 8 WEEKS. Water-quality parameters at this station can vary substantially at different locations in the river. Therefore, water-quality data displayed here characterizes conditions only at the location where water-quality equipment is deployed. The 30-minute precipitation data for this station are temporary and will only be displayed for 120 days. Time series of 1-hour or cumulative daily values will NOT be available for retrieval following the 120-day display period. Although the instrumentation is calibrated at least once a year, the temporary classification means that documented routine inspections and other quality assurance measures are not performed that would make the data acceptable for archival, retrieval, or future use in general scientific or interpretive studies.